BISC208 Spring 2015 Bulk Notes
BISC208 Spring 2015 Bulk Notes BISC208
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verified elite notetaker
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verified elite notetaker
verified elite notetaker
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BISC208 February 13 2015 amp February 172015 Powerpoint 01 Introduction to Evolution Modules 1 Evolution and Life on Earth 2 Introduction to Evolution 3 Genetic Variation in Populations Paradigm Shift Adopting a new reality Ex Declaration of Independence Paradigm Shifts caused by Scienti c Discoveries in the last 500 years Copernicus 1543 Earth man not the center of the universe 0 Sir Isaac Newton 1687 World is governed by natural laws 0 Charles Lyell 1830 Earth is very old and constantly changing Charles Darwin 1859 Life is governed by natural laws man is descended from other organisms and is not unique What is Science Attempt to explain as much as possible of world around us using only natural forces Natural forces remain consistent Supernatural forces change to accommodate opinions What is Evolution Heritable change in characteristics of a population from one generation to the next quotHeritable change genetic changes 0 Genetic variation necessary precursor for evolution genetic differences among individuals 0 Low genetic variation low potential for evolution high high no no Microevolution Gradual changes within a single species over generational time start with one species end with one species Macroevolution One species diversifies into many Species organisms that share a distinctive form look alike can interbreed to produce fertile offspring Population members of same species that are Likely to encounter each other Opportunity to interbreed Phenotypic variation in human populations appears very high See diff in humans Phenotypic variation in natural populations appears very low Can t see diff in plants bugs Phenotypic variation is different from genetic variation Ex Recessive alleles can be present that are not expressed in the phenotype Genetic variation is often much greater than phenotypic variation How can we tell how much genetic variation there actually is 0 Look at arti cial selective breeding 0 Need alleles in right combo so it can be expressed o If genetic variation is low you cannot produce new types by selective breeding o Selective breeding reveals that genetic variation is much greater than phenotypic variation Wolves are same species as dogs amp different types of dogs Different lettuces amp vegetables come from same plant broccoli amp cabbage Genetic Variation within Populations Existing genetic variation in populations can make some evolutionary change possible HOWEVER we can t use arti cial breeding to create a new species 0 We probably can t breed whales from hippos 0 There s not enough existing genetic variation in populations to account for evolution of a completely new species Source of new genetic variation is mutation Mutations are random changes in DNA Because they are random they can be 0 Neutral common 0 Harmful common 0 Bene cial VERY rarely lt EVOLUTION DEPENDS ON THIS 0 Changes of individual bene cial mutation are vanishingly 1miion 0 It s not impossible just takes a LONG TIME Signi cant evolutionary change takes a ong time because bene cial mutations are 50 Took 2 billion years for bacteria to change into amoebas 1 billion seconds more than 31 years First step necessary for Evolution to Occur Production of genetic heritable variation by random mutation good bad neutral Second Step The good genetic variations mutations because established in populations BISC 208 February 17392015 amp February 20 2015 Powerpoint 2 Mechanisms of Microevolution Modules 4 Forces That Drive Evolution amp 5 Calculating Changes In Allele Frequencies Population Genetics 0 Study of genetics at a population level 0 Focus on 0 Genetic variation in populations 0 How it changes Review from 207 Every diploid individual 0 Has one material and one paternal chromosome 0 Each chromosome has a locus for one form of a gene 0 Has two loci for every gene one on each chromosome Each locus can have different alleles forms of a gene Genotype is the combination of alleles at a locus AA or or Aa Phenotype is the outward appearance of a trait Gene pool 0 All of the alleles for every gene in a population Characterize Gene Pool three ways 0 Phenotype frequency percentage of a speci c phenotype in a population brown eyes or blue eyes 0 GenotVDe frequency percentage of a speci c genotype in the population BB or Bb or bb o Allele frequency percentage of all loci occupied by a speci c allele B or b in the population 0 Genetic variation multiple alleles at a given locus in a population If the population is 50 BB individuals and 50 bb individuals Phenotype 50 browneyed 50 blueeyed Genotype 50 BB 0 Bb 50 bb Allele 50 B 50 b Evolution Heritable change in one or more characteristics of a population or species from one generation to the next Population Genetics Change in allele frequencies from one generation to the next Natural selection is only one way that allele frequencies can change HardyWeinburg Law 1908 Problem Could Mendel s laws cause changes in allele frequency Answer Proves that allele frequencies do NOT change simply as a result of Mendelian inheritance Establishes baseline conditions from genetic change in a population No change in Allele Frequencies Evolution will occur when 1 No new mutations occur 2 All alleles have the same effect on survival and reproductive rates all neutral mutations 3 The population is so large that allele frequencies do not change due to random chance effects 4 Only random migration occurs between different populations gene ow 5 Random mating A population that meets these criteria is said to be in HardyWeinberg Equilibrium and will not evolve Mechanisms of Evolution Now we know the conditions under which allele frequencies will NOT change Changes in allele frequencies with populations are caused by four mechanisms violation of HW equilibrium 0 New mutation o Nonrandom gene ow 0 Random genetic drift most important in natural populations 0 Natural selection most important in natural populations Non Directional random or choice evolution variants of genetic drift 0 Genetic drift 0 Changes in allele frequency due to random chance 0 By accident one allele is passed on more than another Unrelated to adaptation Sometimes allele goes extinct just by accidental drift 0 Effects depend on population size Very large population no genetic drift effects are averaged out Medium population weak genetic drift some uctuation Small population strong drift alleles go extinct by accident Founder effect 0 Small group of individuals establishes a new colony 0 Just by chance some alleles are represented more than others 0 Allele frequencies different from original population Unrelated to adaptation o Evolutionary Bottleneck 0 Population reduced dramatically and then rebuilds 0 Some genotypes randomly eliminated when population shrinks 0 New population likely to have less genetic variation fewer alleles 0 Examples Cheetah Almost went extinct 12000 years ago All cheetahs today descended from small pool of survivors Very low genetic variation Weak immune systems genetic defects similar to inbreeding Direction evolution results in increased population 0 Natural selection 0 Evolution due to differences in tness of alleles Less t alleles decrease More t alleles increase 0 Result increase in average tness in the population called adaptation 0 ONLY mechanism of evolution to produce adaptation t between an organism and its environment how well it survives and reproduces Sexual selection BISC208 February 20 2015 amp February 242015 Powerpoint 03A amp B Mechanisms of Microevolution Part 2 Module 6 Effects of Natural Selection Natural Selection Darwin s View 1 Populations are variable 2 Variations are at least in part heritable 3 If heritable variations affect survival and reproductive success then Populations will change over generational time Steps in Natural Selection 1 Production of genetic variation new alleles in populations by random mutation 2 Changes in allele frequencies as a consequence of different tness of alleles Fitness probability that individuals possessing an allele will contribute to the gene pool of the next generation Adaptation is NOT RANDOM Trait Distribution 0 Most phenotypic traits are controlled by many genes NOT like blue eyes and brown eyes 0 These traits show a continuously variable distribution Long Term Studies of Natural Selection in Galapagos Finches Studied the effects of drought induced changes in seed size on beak size 0 Plants produce larger seeds during drought Summary Modern description of Natural Selection 1 Within a population allelic variation arises from random mutations that cause differences in DNA sequences 2 Some alleles encode proteins that enhance an individuals survival or reproductive capability compared to other members of the population 3 Individuals with bene cial alleles are more likely to survive and contribute their alleles to the gene pool of the next generation 4 Over the course of many generations allele frequencies of many different genes in the gene pool may change through natural selection thereby signi cantly altering the characteristics of a population Summary 1 Evolution is a change in allele frequencies from one generation to the next 2 Two causes of evolution a Genetic Drift random stronger in small populations does NOT cause adaptive evolution b Natural Selection occurs when alleles differ in tness causes an increase in t alleles which results in adaptation 3 Fitness relative probability an allele will be transmitted to the next generation 4 Adaption an overall increase in the tness of the population which causes organisms to survive and reproduce more successfully Natural selection patterns Directional Selection 0 Individuals at one extreme of a phenotypic range have greater reproductive success light to dark slow to fast small to big lnitiators 0 New alleles with higher tness introduced 0 Prolonged environmental change global warming changes selection on existing alleles Stabilizing Selection 0 Favors the survival of individuals with intermediate phenotypes not too big not too small just right 0 Extreme values of trait are selected against 0 Examples Clutch size in birds 0 Too many eggs Parents cant feed all 0 Too few eggs Reproductive success too slow DisruptiveDiversifying Selection Favors the survival of two or more extreme phenotypes opposite of stabilizing selection Likely to occur in population that occupy heterogeneous environments 0 Members of the populations can freely interbreed not separate species POWERPOINT BB Darwin s Critics How does natural selection explain traits like these Peacocks tail Even though tail is heavy amp doesn t help with escaping prey helps attract mate looks more attractive Sexual Selection sub category of Natural Selection Traits associated with ability to reproduce How are two sexes o Males 0 Produce microgametes called sperm 0 Sperm are very simple some DNA mitochondria enzymes and a tail 0 Very small contribute very little except half the genetic material to fertilized Females 0 Produce macrogametes called eggs or ova ovum 0 Very large complex energy rich cells 0 Contribute everything else the fertilized egg need in addition to half the genetic material How are two sexes fundamentally different Differ in Reproductive Investment 0 Males 0 Low investment in reproduction 0 One male can fertilize many many females 0 Males will compete for mating opportunities 0 Females 0 High investment in reproduction 0 Can only make a few eggs or fetuses 0 Females will be choosy about mates need to invest their few eggs wisely Sexual Selection subcategories lntrasexual selection 0 Competition among males 0 Exaggerated weapons of competition lntersexual selection 0 Female choice choosy o Showy exaggerated character for males 0 More likely for them to be chosen by males 0 Surviving does not matter if females do not choose you Guppies Sexual Selection Explains traits that decrease survival but increase reproductive success Example Male guppy is brightly colored Brightly colored males are Healthy stronger and more disease resistant Preferred by females BUT More likely to be noticed and eaten by predators Balancing Natural and Sexual Selection Relative abundance of bright and dull colored males depends on the balance between sexual selection which favors bright coloring escape from predation which favors dull coloring BISC208 February 27th 2015 Powerpoint 04 Macroevolution and Speciation Module 7 amp 8 Pace of Speciation Human Evolution Marcoevolution divergence one species becomes many 0 One very small organism came from nonliving cells and then everything diverged and evolved from that very small living a bacteria 0 98 of human DNA shared by chimpanzees o 50amp 60 of human DNA shared with bacteria What are species 0 Different species 0 gene pools that are reproductively isolated and therefore evolving independenUy Reproductive Isolation no gene ow no sharing of new alleles that arise by mutation Therefore evolve independently Reproductively isolated Gene Pools No gene flow 1 gene flows locks gene pools together Less than 1 percent needed Independent Evolution Character Divergence Random mutation establishes different alleles in isolated gene pools isolated gene pools follow different evolutionary paths the gene pools diverge and eventually can become separate species Speciation How does one gene pool become two reproductively isolated gene pools How Do New Species Arise Disruptive Selection Selection for extremes within a gene pool Causes character divergence NOT strong enough to result in reproductive isolation How do gene pools become reproductively isolated Geographical Isolation some event geological migration to isolated area establishes geographically separated gene pools Called Allopatric speciation gene pools become geographically isolated rst before divergence Steps in Allopatric Speciation Reproductive isolation by spatial geographical separation of two gene pools Random genetic differences established Differential evolution causes divergence in each gene pool Divergence comes after isolation Secondary Contact Two previously separated populations come back into contact If populations have diverged a lot 0 no interbreeding 0 remain separate species Ex Male donkey amp female horse l Mule o If populations have diverged less 0 lnterbreeding occurs and fertile hybrids are produced 0 gene ow reestablished Two Fates of Hybrid Zones 1 The two gene pools merge back into one species 2 Hybridization stops and two species are maintained Merge back into one species when 1 New adaptations are compatible 2 No tness cost to hybridization 3 Gene ow increases 4 Gene pools lose their independent evolutionary trajectories Two Species are maintained when 1 New adaptations are incompatible 2 Therefore hybrids have reduced tness 3 Therefore organisms that avoid hybridization have increased tness 4 These avoidance traits increase and are called Reproductive Isolating Mechanisms Keeps gene pools separate leaving two separate species which continue to diverge Reproductive isolating Mechanisms 1 Ligers have lower tness 2 Some lions and tigers possess alleles that make them more aggressive toward the other species and less likely to hybridize 3 These individuals have higher tness and their alleles increase by natural selection 4 lnterspeci c aggression evolves and reestablishes gene pool isolation 5 Adaptations that evolve AFI39ER secondary contact and hybridization 6 Reestablish reproductive isolation and separation of two species 7 Take many forms behavior physiology anatomy etc Speciation in Galapagos Finches Small number of Blueblack Grassquits reach Galapagos Islands from mainland Birds spread to all the islands migration Islands are far enough apart to isolate gene poos Divergence occurs on different islands Secondary contact promotes evolution of isolating mechanisms Gene pools are isolated evolution continues in the new species which become even more different Summary Speciation 1 Gene Pools become geographically isolated 2 Divergence occurs in geographically isolated gene poos 3 Secondary contact promotes evolution of reproductive isolation 4 Reproductively isolated gene poos further diverge BISC208 March 10 2015 amp March 13392015 Powerpoint 06 Introduction to Homeostasis Exchange and Transport Module 9 Homeostasis Evolution Review No Evolution will occur when 0 No genetic variation oAll populations are at HW Equilibrium Unity in Diversity Unity due to the accuracy of DNA replication Diversity due to the errors in DNA replication not 100 accurate Organ Systems Rule The larger the organism the more complex the organ systems All organisms must accomplish two basic functions to survive Exchange substances with their environment 0 Transport substances externally and internally Both these functions are limited by larger size 0 Exchange surface area 0 Transport distance Organ systems have evolved to solve problems of size not because they have any intrinsic advantage Surface to Volume ratio constrains exchange Sphere example SV decreases as size increases 0 Solutions 0 Folds increases surface area 0 Geometry long and skinny or at structures increases surface area 0 Hollow instead of solid structures reduces volume 0 BEST SOLUTION Long skinny hollow folded tube highest surface area for a given volume Distance constrains transport How do small organisms transport substances Diffusion o Requires no energy 0 Requires favorable concentration gradient 0 Works over microscopic distances only 0 Active Transport 0 Requires energy 0 Works against concentration gradient 0 Works over microscopic distances only Distance constrains transport solutions 0 Bulk Transport Systems lungs heart digestive system bladder 0 Use large muscular pumps to push mass quantities of substances through pipes o Requires energy 0 Able to manipulate concentration gradients to allow individual cells to use diffusion Summary 0 Because of their size large organism have dif culty exchanging and transporting vital substances 0 Structure and function of large organisms is driven by need to exchange with their environments 0 Large complex organ systems have evolved to overcome the problems of being large 0 Environment is as much a part of an organism s physiology as it s internal state Environmental Interfaces Three examples of why the environment has to be considered 0 Example 1Environment determines Physiology 0 Temperature Regulation Warm blooded Endotherm Cold blooded Ectotherm Behavioralthermoregulation Homeotherm constant body temperature Poikilotherm variable body temperature Consideration of environment leads to much richer view of thermoregulation lnternal or external heat source Constant or variable body temperature 0 Active regulator or passive conformer Humans lnternal constant active Hummingbird lnternal variable active Lizard day External constant active Lizard night External variable passive 0 Example 2 Environment determines Morphology o What is the shape of a plant Plant shape altered by predation Morphology of plant is a function of its environment Cannot be de ned independent of the environment 0 Example 3 Environment determines Biochemistry 0 Does plant product defensive compounds Only after it gets eaten Depends on environment presence of predators 0 Example 4 Environment determines Health o Is adult onset Type II diabetes a disease 0 Primates have high quotsugar drivequot to feed their large brains especially humans In low sudar concentrations primitive conditions this is adaptive and causes them to seek our sugar sources like honey and fruit In high sugar concentrations civilization it causes the to overheat and overstimulate insulin 0 What do organ systems do 0 Exchange substances move things in and out of the body 0 Transport substances move things around the body Purpose of exchange and transport maintain homeostasis Homeostasis maintained by regulating the functions of organ systems Regulatory systems in animals 0 Nervous system 0 Endocrine system Regulation occurs by negative feedback 0 Ex Sweating to get cooler Shivering to get warmer Negative Feedback Components 0 Set point desired condition 0 Sensor measures the regulated condition 0 Error signal different between the set point and the sensor reading Negative Feedback occurs when 0 The sensor causes adjustments In the opposite direction of the error signal To reduce the error signal BISC208 March 17 2015 amp March 202015 Powerpoint 07 Internal Transport in Animals Module 10 Circulatory System Module 11 The Heart Circulatory Systems Internal Transport 0 Large animals must transport LONG distances 0 Cannot use ONLY diffusion and active transport 0 Have evolve circulatory systems to move substances around the body by bulk transport Components 0 Pump heart muscle that applies pressure to uid to move it by bulk transport Fluid blood or hemolymph Tubes blood vessels Two types of circulatory systems Open Circulatory Systems 0 Most common type of circulatory system all small invertebrates 0 Heart pumps tissue uid called hemolymph NO blood lnterstitial uid with blood components Contains dissolved respiratory pigments Oxygen transport No red blood cells 0 No tubes or open tubes distribute hemolymph around the body Arteries and veins but NO capillaries Closed Circulatory Systems 0 Closed tubes 0 Blood is contained inside closed tubes and recirculated Respiratory pigment hemoglobin contained in red blood cells to transport oxygen Many invertebrates and all vertebrates Advantage greater control of delivery Can put blood under higher pressure Types of Blood Vessels o Arteries 0 Carry blood away from the heart 0 High pressure thick elastic walls 0 High blood velocity 0 No exchange with tissues 0 Veins 0 Carry blood away from capillaries usually to the heart 0 Low pressure thin walls valves 0 High blood velocity 0 No exchange with tissues Capillaries 0 Thin walled vessels 0 Exchange sites 0 Low blood velocity 0 High resistance reduces blood pressure Evolution of vertebrate circulatory systems 0 Start with ONE circuit 0 Heart Gills or lungs Body 0 Progressive separation of 0 Blood that goes to the capillaries in the respiratory surface lungs or gills 0 Blood that goes to capillaries in the rest of the body 0 This culminates in two circuits 0 A pulmonary lung or gills circuit 0 A systemic body circuit 0 Heart Gills or lungs Heart Body Fish Circulatory System 0 Single circuit for both gills and body 2chambered heart 0 Atrium priming pump 0 Ventricle main pump 0 Blood pressure 0 High between ventricle and gills low everywhere else 0 Blood is pumped to body under low pressure 0 OK for sh with no gravity to overcome Amphibian and Reptile Circulatory Systems Partially separated systemic and pulmonary circulation 3chambered heart 0 Primary advantage high pressure delivery of blood to systemic capillaries unlike sh with low pressure 0 However both systemic and pulmonary circuits have the same pressure 0 Limited mixing of deoxygenated and oxygenated blood in ventricle only about 10 mixes Vertebrate Circulatory Systems Crocodilians Birds Mammals 0 True fourchambered hearts 0 Completely separate pulmonary and systemic circuits 0 Advantages of separate circuits are Main advantage Separate circuits have different pressures high pressure for systemic circuit Minor advantage Oxygenated and deoxygenated blood cannot mix at all Heartbeat Cardiac Cycle 4chambered heart 0 The left and right sides are separate pumps 0 The left pump delivers blood to systemic circuit Small Intestine Kidney Body Tissues o The right pump delivers blood to pulmonary circuit Lungs Heart Valves 0 Oneway doors that prevent back ow o Atrioventricular valves Between the atria and the ventricles Prevent back ow into the atria when the ventricles contract 0 Semilunar valves Between the ventricle and artery Prevent back ow from the major arteries into the ventricles Cardiac Cycle one heartbeat 0 Diastole lling with blood 0 Blood enters the relaxed heart from the vein 0 Blood lls the ventricle and then the atrium o Atrium contracts 0 Valves in veins prevent back ow 0 Blood forced through AV valve into ventricle Systole pumping blood 0 Ventricles contract 0 Back pressure forces AV valve to shut LUB 0 Pressure forces semilunar valves open and blood forced into artery 0 Ventricles relax 0 Elastic recoil of artery causes back pressure which closes semilunar valve DUB Regulation of the Heartbeat What causes the heart muscle to contract Skeletal muscle neurogenic contractions 0 Cardiac muscle myogenic contractions What coordinates the heartbeat 0 Both atria contract in unison then both ventricles contract in unison 0 Heart muscle cells are connected by dab iunctions contraction stimulus ows from one cell to another 0 Conducting system specialized muscle bers carry contraction stimulus throughout heart 0 NO NERVES Heartbeat Since heart cells are interconnected fastest beating component drives the rest of the heart Components of the Conduction System Heartbeat Pathway of Contraction Stimulus Pacemaker 0 Patch of cells in the right atrium rst set of cells to contract initiate contraction stimulus Atrium muscle cells 0 Contraction stimulus spreads through gap junctions of normal atrial muscle cells to both atria and they contract together 0 Atrioventricular AV Node 0 Small bundle of bers that connects atria and ventricles 0 Slow bers contraction stimulus slows here causing delay between contraction of atria and contraction of ventricles Bundle of His and Purkinje Fibers 0 Spread contraction stimulus quickly from AV node throughout the ventricles 0 Both ventricles contract simultaneously Heartbeat is myogenic Pacemaker spontaneously depolarizes generating contraction stimulus Nervous system Sympathetic nervous system increases heart rate Parasympathetic nervous system decreases heart rate Pumping of blood in veins Veins Pressure in veins is very low 0 High resistance of capillaries completely dissipates pressure from heart 0 No pressure from heart to move blood 0 What applies pressure in veins to move blood 0 1 Skeletal Muscle Pump Veins are squeezed when skeletal muscles contract 0 2 Respiratory Pump Breathing creates a pushpull pressure on veins around the heart 0 Why does blood move only towards the heart 0 Oneway valves in veins prevent back ow o Veins are only blood vessels with valves 0 Arteries and capillaries rely on pressure difference Flow away from high pressure in heart BISC208 March 24 2015 Powerpoint 09 Principles of Nutrition Module 14 Digestion Overview Nutrition Nutrient Requirements for all organisms Energy sources 0 Used to make ATP biological energy 0 Matter 0 Used for structural and metabolic components 0 Carbon Oxygen Hydrogen Nitrogen o Ions and micronutrients Two radically different strategies for acquiring theses substances 0 Autotrophs photosynthetic Most plants some bacteria some protists Rely mostly on inorganic nonliving sources of matter and energy 0 Energy Trap solar energy Matter Use mainly inorganic sources of matter including gases 02 C02 H20 Synthesize substances they need Energy Sources for Autotrophs Photosynthesis 0 Produce sugar from sunlight Cellular Respiration 0 Burn sugar with oxygen oxidize to make ATP 0 Heterotrophs nonphotosynthetic Most animals bacteria protists Organic sources of energy and matter 0 Organic from living organisms 0 Must obtain their nutrition by eating other organisms Completely dependent on autotrophs for energy and most matter Energy Sources for Heterotrophs Chemical bonds of food molecules are broken 0 Energy is released 0 Transferred to highenergy phosphate bond of ATP Eventually all energy transferred to ATP is released as heat when ATP is used 0 Cellular Respiration 0 Burns sugar with oxygen oxidize to make ATP Metabolic Rate 0 Heat 0 Cannot be used in biological reactions 0 Released immediately to the environment 0 Rate of heat production rate of energy use by an organisms Energy measured in units of heat energy called a calorie English or joule metric Measure of overall energy needs What components of food provide this energy Carbohydrates Sugars and starches 0 Short term energy supply 0 Stored in liver and muscle as glycogen 0 Simple sugars 0 Complex starches 0 Fat lipid or triglyceride 0 Primary energy storage medium 0 Very dense caloric content 0 Fat components can be burned in cellular respiration fatty acids 0 Glycerol 3 fatty acids 0 Protein 0 Only used for energy in emergency 0 Amino acids must be converted to carbohydrates Matter Heterotrophs also require matter from food 0 Require organic sources of H O C N oAlso require structural molecules called carbon skeletons synthesized by autotrophs Carbohydrate skeletons Example acetyl group basis for many fats and amino acids are synthesized Amino acid Nitrogen source oMany required in the diet to synthesize proteins Essential fatty acids from fat Food oMajor Food Macromolecules o Carbohydrate Example Glucose Energy and carbon skeletons o Fat Energy and carbon skeletons o Protein Long polymers of amino acids Energy carbohydrate skeletons amino acids nitrogen BISC208 April 7th amp 10th 2015 Powerpoint 10 Animal Nutrition Module 15 Process of Digestion Digestive System oNutrient needs are met by the digestive system Food macromolecules must be broken down digested into subunits o Carbohydrates into sugars 0 Proteins into amino acids which contain N oBecause o Easier to absorb into the body 0 Components can be used to build need polymers o Food stays quotoutside the body until it is absorbed into the body Why are food macromolecules digested broken down outside the body Macromolecules are not readily absorbed oEnzymes have to distinguish self from quotfoodquot 0 Mucous protects gut from being digested along with food ommune system has to distinguish self from quotfoodquot 0 Food macromolecules nonself therefore would simulate immune response 0 Immune system does not react to small molecules amino acids sugars free fatty acids Phases of Digestion o Ingestion Food is taken into a body cavity gut lumen 0 Inside the gut outside the body Digestion Food is broken down outside the body 0 Physical prepare food for chemical digestion Water added to food Food is broken down into small particles to expose more surface area 0 Chemical food macromolecules carbohydrates proteins fats chemically broken down Into subunits sugars amino acids fatty acids by enzymes in the gut Absorption Subunits are absorbed into the body Digestion Most animals have a tubular gut o Mouth that takes in food 0 Anus for waste excretion Oneway processing food why o Tubular gut has different regions that are specialized for different funcUons Generalized Digestive System 1 Buccal cavity mouth cavity 0 lngeonn 0 Physical Digestion 2 Stomachs crops and gizzards Storage Chambers 0 Physical Digestion 3 Midgut or lntestine Chemical Digestion Absorption 4 Hindgut Recovers water and ions 0 Stores undigested material feces o Endosymbiotic bacteria live in the hindguts of many animals 0 These bacteria 0 Obtain nutrients from the food 0 Contribute to the digestive process of the host 0 Digest cellulose in some herbivores cows termites rabbits etc The Human Digestive System 0 Mouth o Physical Digestion Chewing Saliva adds water 0 Chemical Digestion Salivary Amylase Enzyme that partially digests carbohydrate Salivary Lipase 0 Enzyme that partially digests fat Esophagus 0 Bulk transport of food from mouth to stomach o Peristalsis sequential contraction of circular muscles lining gut One mechanism to ensure oneway bulk transport Stomach 0 Physical Digestion Food is churned for hours Water added HCl Acid added Dissolves food Sterilizes food 0 Chemical Digestion Pepsin enzyme that partially digest protein Absorption As organisms get larger they need more surface area in their midgut to increase their ability to exchange with their environment 0 Small intestine o OrganismEnvironment Interface of Digestive System Very large surface area for exchange Food enters the body here 0 Physical Digestion Bile from liver Stored in gallbladder breaks up fat droplets 0 Acid Neutralization Bicarbonate from pancreas neutralizes stomach acid 0 Chemical Digestion Many enzymes from wall of small intestine and from pancreas complete chemical digestion of carbohydrate fat and protein 0 Absorption Evolved large surface area to maximize absorption 0 Wall of intestine is richly folded 0 Individual folds have ngerlike projections called villi 6000 sq ft 0 Individual cell membranes have many folds called microvilli 50X increase Together villi and microvilli present an enormous surface area for the absorption nutrients 300000 sq ft When you re digesting food it goes from the small intestine to the liver rst so it can detoxify Human Small Intestine 0 Absorption Only occurs in small intestine NOT stomach Fatty acids amino acids sugars ions water are absorbed across the wall of the small intestine into the body 0 Processes include Diffusion Facilitated Diffusion Active Transport 0 Carried in blood to liver and then to the rest of the body 0 Large Intestine or Colon o Absorbs water and ions producing semisolid feces from indigestible material 0 Too much water absorption results in constipation 0 Too little water absorption results in diarrhea o Intestinal bacteria in human large intestine 0 Produce gases such as methane and hydrogen sul de as by products of anaerobic metabolism no oxygen o Synthesize vitamin K which is absorbed into the body 0 Fecal material mostly dead cells from the lining of the gut and bacteria Feces do not contain metabolic produced in the body 0 Exception biirubin broken down hemoglobin added via bie Heterotroph Nutrition Summary Heterotroph digest organic and inorganic food sources to meet their requirements for matter and energy Digestion occurs outside the body prior to absorption 0 The digestive system is a long tube that has sections that are specialized for the various phases of digestion o lngeonn 0 Physical digestion 0 Chemical digestion 0 Absorption BISC208 March 20 2015 amp March 242015 Powerpoint 08 Transport in Plants Module 12 Plant Structure and Function 13 Plant Transport Systems Transport in Plants 0 Challenges 0 Need for 2way bulk transport in large plants Water and minerals in the soil must brought to the leaves Carbohydrate made in the leaves must be brought to rest of plant 0 High Demand A large tree loses up to 200 litersday 50 gallons in sleaves Why do plants lose water 0 Must have large surface area exposed to exchange gas stomata in leaves Essentially they lose water when they breathe Same for animals 0 Must replace lost water by uptake at roots and bulk transport to rest of plant 0 Animals Giraffe transport of water Gigantic heart with very thick ventricle muscle Valves in neck arteries Mechanisms available for bulk ow in plants 0 Pumps hearts NO 0 Must rely on Active Transport Diffusion Question How have plants made these operate over long distance Tran5port of Water and Minerals oRoots take up water and minerals oXylem transport from roots throughout plant oTracheary Elements tubes of empty dead cell walls joined together like a chain of soda straws Tracheids primitive connected by pores Vessel elements more advanced completely open ends 0 Question How do organisms move water 0 Water never moved by primary active transport 0 Water usually moved by osmosis Special case of diffusion across semipermeable barrier Create osmotic gradient by active transport of minerals Water follows osmotic gradient high to low 0 Uptake in the roots 0 Minerals and ions Diffusion Active transport 0 Water Diffusion Osmosis 0 Moving Water Up the Xylem o TranspirationCohesionTension Mechanism Cohesion H20 molecules in Xylem connected by hydrogen bonds 0 Connected chain of H20 molecules from roots toleaves Transpiration H20 molecules at the top of chain evaporate from leaf Tension as water molecule evaporates it pulls on the chain below because of it s hydrogen bonds 0 This tension pulls the water column upward transpirational pull 0 According to the model water movement up the stem is driven by evaporation and requires no biological energy NO ATP is used Sunlight drives evaporation which drives the transport mechanism Transport of Carbohydrate o Phloem transport from leaves throughout plant 0 Sieve Tube Elements tubes ofjoined living cells Like xylem like a chain of soda straws Filled with cytoplasm that is continuous from cell to cell 0 Companion cell adjacent support cells Moving Water in the Phloem up and down Phloem is a long sealed tube unlike open xylem tube 0 Fluid in the phloem moves 0 From sources where sugar is made leaves 0 To sinks where sugar is needed entire plant Pressure Flow Mechanism 0 Source Sugar moved INTO phloem tube by Active Transport Creates osmotic gradient with high solute inside Water ows INTO phloem by osmosis This creates HIGH pressure in the source end of the phloem Sugar moved OUT of the phloem by Active Transport Create osmotic gradient with high solute outside Water ows OUT of phloem by osmosis This creates LOW pressure in the sink end of the phloem Fluid ows from high to low pressure creating bulk ow from the source to the sink Summary Xylem transports water and minerals from roots to leaves using only evaporation Phloem transports sugar from leaves using only local active transport Plants have a high volume reasonably fast bulk transport system that operates over heights far exceeding that of animals for an astonishingly low energy cost BISC208 April 10thamp 14th 2015 Powerpoint 11 Plant Nutrition Module 16 Plant Nutrients What is a plant 0 Land plants have stomates Plants and Algae Land Plants and Green Algae share these traits o Chlorophyll A and B used in photosynthesis 0 Cell wall made of cellulose Provides rigid support and protection Forever dooms plants to limited mobility To survive on land plants different from algae in o Cuticle a waxy covering that prevents drying o Embryos young plants in protective structure 0 Plants are referred to as embryophytes Animal Characteristics All animals share some of these characteristics 0 Heterotrophic do not photosynthesize o No cell walls Nerves muscles capacity to move Sensory structures and nervous system Extracellular matrix Gap junctions between cells Nutrition Autotrophs 0 Most plants some bacteria and some protists o Photosynthesis sugar from sunlight 0 Inorganic matter Gases All autotrophs can use 02 C02 0 A few can also use N2 Synthesize substances they need 0 Sugar made by photosynthesis is used for Energy stored as starch Structure main component of cellulose 0 Animals and Plants differ in their main structural components Animals are mostly protein muscles Plants are mostly carbohydrate cellulose The Acquisition of Nutrients oAutotrophs use inorganic sources of matter 0 Heterotrophs eat autotrophs only need to breathe and drink o Carbon and oxygen Comes from C02 and 02 in the air o Hydrogen From water H20 o Nitrogen Bacteria convert N2 in air to forms that plants can use Of the major nutrients only nitrogen is limiting for plants 0 Main component of fertilizer o In addition to nitrogen plants require a number of other inorganic ions both cations and anions H 0 Nutrition organismenvironment interface for plants What is the small intestine of a plant Roots o Adaptations to increase surface area 0 Root hairs equivalent to villi in animals 0 Plants absorb inorganic ions and water through their roots oAcquisition of Cations by plant roots o Plants need positively charged ions Cations Mg2 Ca2 and K Cay particles in soil have a negative charge Cay binds cations oTo disassociate cations from clay plant roots produce acid two ways Release H directly Release C02 reacts with water to produce Carbonic Acid H o H ions displace cations from clay particles by binding to negative charges instead olon Exchange o 1 Roots release protons H directly into soil o 2 Roots release C02 which reacts with water to produce carbonic acid o lon Exchange H bumps cations off clay particle to be absorbed by roots oAcquisition of Anions by Plant Roots o Anions are not held by the soil oThe major plant nutrient anion is NO339nitrate o Nitrate is transported into plant roots against a concentration gradient Not pumped directly Primary Active Transport lnstead uses Secondary Active Transport Same process used in our kidneys and small intestines to transport other substances like glucose 0 Animals use Na pumps plants use H pumps Secondary Active Transport o Plants use active transport to pump H outside root o Creates high concentration outside of H outside root o Diffusion gradient favoring H moving into plant o H can only move in through a symporter Molecular gate that requires two different molecules to open o Roots contain an HNO339symporter H moves into plant by diffusion Symporter uses driving force of H diffusion to move NO339against a concentration gradient by diffusion Acquisition of Anions by Plant Roots o Nitrogen is hard to get oOften limits plant growth Ways to deal with nitrogen limitation o Most common simply stop growing Nitrogen fertilizer stimulates growth o More specialized Endosymbiosis Carnivory Legumes encourage nitrogen xing bacteria called Rhizobium to infect their roots Acquisition of Anions Endosymbiosis 0 Neither plants or animals can access atmospheric N2 oSome bacteria can use N2 directly Nitrogen Fixation 0 Plants of Legume Family o Alfalfa clover peas beans soybeans peanuts etc Symbiotic relationship nitrogen xing bacteria live in their o roots 0 Growth NOT limited by nitrogen Acquisition of Anions Carnivory o In a turn of the usual events some plants get nitrogen by eating animals 0 Animals are mostly protein a rich source of nitrogen BISC208 April 14th 2015 April 17th Powerpoint 12 Gas Exchange in Animals Module 17 Respiratory Systems Gas Exchange Respiration and Photosynthesis require gases 0 Cellular Respiration 02 used waste C02 released 0 Photosynthesis C02 used waste 02 released Organism must exchange gas with their environment 0 Air high 02 low C02 0 Water low 02 high C02 Requires a Respiratory Surface 0 OrganismEnvironment Interface direct contact 0 High surface area 0 Moist gases must be dissolved Animal Respiratory Surfaces Lungs All breathers have invaginated respiratory surfaces called lungs Gills Nearly all water breathers have evaginated respiratory surfaces called gills Ventilation of Respiratory Surface 0 Most large organisms use bulk ow of the environment water or air past the respiratory surface 0 Maintain favorable concentration gradient 0 Diffusion can be used at the respiratory surface 0 High potential for water loss or gain Gas Exchange in Animals 0 Gills 0 Easy to ventilate needed for water Unidirectional ventilation countercurrent exchange Hard to support requires water to maintain surface area High water exchange but at least is always available Why do nearly all aquatic organisms use gills to breathe water Easily ventilated respiratory surface Gills collapse when they re not in water because of gravity surface area decreases 0000 o Lungs 0 Hard to ventilate OK for air only 0 Easy to support required for air 0 High water loss by evaporation forced to use insufficient tidal bidirectional ventilation to control water loss 0 Why do all airbreathing organisms use lungs Gills Lungs Structure Evagination lnvagination Ventilation Easy Hard Support Hard Easy Desiccation High High controllable Ventilation Unidirectional Usually tidal bidirectional Fish Gills 0 Breathing water 0 Low 02 means high ventilation rate required High ventilation rate uncontrolled water loss or gain controlled by drinking and kidney Gills can be unidirectionally ventilated in one opening out another because no control of water loss oCountercurrent exchange 0 Blood and water ow in opposite directions o Great increase in efficiency Breathing Air Breathing air requires a moist respiratory surface exposed to air o Tremendous potential for water loss Water loss controlled by o Lower Ventilation Rate High 02 in air lower ventilation rate compared to water reduces water loss oTida Ventilation Breathe in and out of same opening Reduces water loss o How does tidal ventilation reduce water loss at respiratory surface Nasa passages recover water in exhaled air olnhale dry air o Water evaporates from sinus passages causing them to cool oExhale moist air from lungs o Warm moist air from lungs 100 humidity passes over cool sinus passages and water condenses out o Leaving drier air to be exhaled from nose humans 75 humidity therefore saving 25 of the water exhaled air Water savings oAir is 100 humidity in lungs due to evaporation from respiratory surface 0 Humans Exhaed air from nose is 75 humidity 25 of water in exhaled air recovered in sinuses o Camels and Kangaroo Rats Exhaed air is completely dry 0 humidity Recover 100 of water in exhaled air Nasa passages in camel of are 20 ft long Breathing air 0 Bene ts of tidal ventilation 0 Recovery of water from exhaled air 0 Costs of tidal bidirectional ventilation o No countercurrent exchange 0 Dead spaces virtual Incomplete ventilation Loss of ef ciency Humans 0 Classic quotdead endquot tidally ventilated lungs 0 Non exchange surfaces Trachea bronchi and bronchioles Low surface area Rigid 0 Exchange surface Alveolus site of gas exchange 0 Huge total surface area thousands of alveoli Moist surface 0 Turbulent air ow no countercurrent exchange Elastic Blind dead end sac balloon xed to end of soda straws Tidal Ventilation o Inef cient due to o 1 Dead Spaces 0 Expiration Some quotstalequot air always remains in lung 0 Inspiration wasted air contained in air passages 2 Incomplete Exchange 0 Only 10 of air exchanged at each breath at rest Consequence o Atmospheric air is 20 02 0 Air in lungs is 15 02 Ventilation of lungs o How do you expand and contract each of thousands of individual alveoli Seal them inside a larger container that expands and contracts Pleura Dual layered membrane attened balloon surrounding lung and enclosing it in sealed space 0 Outer membrane is attached to diaphragm muscle Breathing Diaphragm contracts and pulls down on pleura Volume of pleural cavity enlarges creating lower pressure in lungs suction or negative pressure 0 Air rushes into lungs Diaphragm relaxes and moves upward reducing pleural cavity volume and increasing pressure in lung forcing air out 0 Pinnacle of Vertebrae Gas Exchange Systems 0 Early climbers on Everest marveled at watching birds y while humans were sucking on oxygen bottles 0 Birds have been tracked on radar ying at extremely high altitudes 0 Have a unidirectionally ventilated countercurrent lung 0 Bird Lung 0 5X efficient as mammalian lung 0 Rigid lung ventilated by air sacs 0 Air sacs push and pull air across lungs in internal one way circuit 0 Unidirectional ventilation internal circuit Countercurrent exchange No dead spaces 100 ventilation 20 02 at respiratory surface Fresh air while inhaling and exhaling 0 Control of Water loss Still only breathe in and out through one opening to control water loss 0 The other solution 0 lnsect trachea Fine tubes that bring air directly to cells Air diffuses from there to cells No blood no hemoglobin in most 0 Ventilation Inefficient dead end tubes Muscle movement and diffusion Potentially limits size of insects to about 15 cm BISC208 April 21St amp 24th 2015 Powerpoint 13 Gas Exchange 2 Blood Transoort of Resbiratorv Gases lnternal Transport of Gas 0 C02 is water soluble 0 C02 H20 gt H2CO3 gt H o Dissolved C02 makes blood more acidic 0 02 is only weakly soluble in water 0 Hemoglobin Respiratory pigment red Contained in red blood cells 6OX the capacity of plasma to transport 02 Hemoglobin Hb 0 Large protein 0 4 polypeptide subunits Each has a heme noncontaining group 4 per hemoglobin molecule 0 Each heme group can reversibly bind ONE molecule of 02 O 02 ltgt o Reversible binding Means oxygen uptake and delivery is regulated by local concentration of oxygen Laws of Equilibrium 02 concentration Mgh in lungs 02 binds 02 concentration ow in tissues 02 released Cooperativity o All four 02 molecules do not bind to hemoglobin with the same af nity Binding the rst molecule of 02 makes the second binding easier Binding of second makes binding of the third easier Binding of the third makes fourth HARDER o Spreads out 02 binding to hemoglobin over greater range of 02 concentrations Allows ne tuning of 02 delivery to meet tissue demands How 0 Gas exchange occurs in only two places 0 Capillaries in lungs o Capillaries in tissues 0 NO GAS EXCHANGE in arteries or veins How much 02 binds determined by local 02 concentration in capillary Blood fully saturated with 02 in lungs always 98 0 At rest 0 02 concentration still fairly high in tissue 0 Only about 20 of 02 is released 0 During activity o 02 concentration is lower in tissue due to activity using up 02 more 02 is released because of Law of Mass Action Subtract concentration from 98 to calculate how much oxygen was released to tissues after hemoglobin travels in blood Oxygenhemoglobin Dissociation Curve 0 Indicates amount of 02 bound to hemoglobin at given 02 concentration 0 Does not represent changes in the body but allows us to determine those changes Plant Respiration Photosynthesis and Respiration create need for gas exchange 0 Leaves Very high surface area to capture photons Also used for gas exchange Equivalent to breathing air with gills 0 Plants do not use bulk transport for gas exchange Why not Gas used directly in leaves diffused to chloroplasts 0 Large surface area of leaf creates potential water loss problem Covered in waxy cuticle that is impermeable to water Also impermeable to C02 0 Stomate Pits in the surface of the leaf Moist surface Can be opened or closed at entrance by guard cells High surface area Actually more like thousands of miniature lungs Projections called trichomes projections How do plants control water loss during respiration 0 They stop breathing Guard Cells 0 Control opening and closing of stomata 0 Open stomata in the light when doing photosynthesis 0 Close in the dark when no need for C02 0 Close if too much water is being lost 0 Tradeoff in water loss and gas exchange similar to animals Transpiration and the Stomata Opening of the stomata light required o Blue light activates a proton pump o Pump protons H ions out of guard cells 0 Creates negative charge inside cell 0 Attracts K inside o Water passively follows concentration by osmosis o Guard cells change shape plump up and form a gap between them Closing of the stomata o Guard cells close in absence of light Active transport of protons stops K diffuses out of the cell and water follows o Guard cells close when the plant is dehydrated Dehydrated plants cells produce a hormone Abscisic Acid lnhibits the proton pump even when light is present Guard cells lose water and close BISC208 Ap l242015 Powerpoint 14 Excretion 1 Excretory System 0 Functions of Excretory System 0 Excrete Metabolic Wastes 0 Tissue Fluid and Water Balance 0 Excrete lngested Toxins Metabolic Waste 0 Carbohydrate C02 and water 0 Fat C02 and water 0 Protein C02 water and ammonia Excreting Nitrogenous Wastes o Ammonia 0 Highly toxic waste product 0 How do we deal with it Aquatic animals 0 Ammonia very soluble in water 0 Diffuses rapidly across gill membranes down concentration gradient 0 Water breathing animals excrete ammonia immediately Terrestrial Animals 0 Ammonia is very toxic Cannot build up anywhere in body Must be kept very dilute Would cost lots of water to excrete directly 0 Solution convert ammonia to less toxic molecules 0 C D Q o Mammals and some amphibians o Moderately toxic can be concentrated for excretion to save water 0 Moderate energy cost Uric Acid 0 Birds reptiles some amphibians insects 0 High energy cost 0 Nontoxic excreted as a solid so saves water 0 Easy to store in eggs Tissue Fluid and Water Balance 0 Water Balance Problems o Aquatic osmosis at the gills Fresh water 0 Environment is hypoosmotic more dilute Constantly GAIN water through gills Marine Environment is hyperosmotic more concentrated Constantly LOSE water through gills o Terrestrial Unless air is saturated 100 humidity constantly LOSE water by evaporation oWater Balance Solutions o 1 Osmoconformers Allow body uids to be at equilibrium with environment oSmall marine invertebrates tolerate wide range of osmolality oSharks and Rays oAllow urea to build up in blood until solute concentration of blood equals sea water o No osmotic gradient no water loss o 2 Osmoregulators Actively regulate water intake and loss to maintain water homeostasis oAquatic Osmoregulators o Fresh water organisms too much water gain through gills Do not drink Constantly produce large quantities of dilute urine o Salt water organisms dehydrating environment desert Produce concentrated urine Drink constantly How do they deal with all the salt oExcrete excess salt with special glands 0 Marine Fish chloride cells in gills 0 Marine Birds and Reptiles salt glands in nose 0 Marine Mammals very powerful kidneys BISC208 May 1st 2015 Powerpoint 15 Excretion 2 Study old exams 40 questions new questions 60 Salt water lose water at gill Fresh water gain water at gill Tissue Fluid and Water Balance 0 Terrestrial Environments o Kidney produces concentrated urine so metabolic wastes and toxins can be excreted with less water 0 First kidney challenge Filter blood by separating good from bad Excrete the bad metabolic wastes and toxins Retain the good sugars amino acids etc 0 Second kidney challenge How do you produce concentrated urine Needed to save water Most move water against a concentration gradient Use active transport NO cant actively transport water Moving water Use osmosis l Way to concentrate urine 0 Types of kidneys 0 Simple secretion kidney One step Kidney removes bad from blood directly urea placed into urine good stays in blood stream 0 Filtration Reabsorption Kidnev Two steps 0 Good amp bad are removed from blood ltered into the urine 0 Good is reabsorbed back into the blood bad is left for excretion Doesn t recognize good from blood removes both Advantage of Filtration Reabsorption Kidney All toxins excreted Basically anything not recognized as good is excreted What type of kidney is best 0 All large organisms have ltration reabsorption kidney 0 What happens to novel toxin or poison something the body does not recognize Secretion kidney left in blood Filtration Reabsorption Kidney excreted Vertebrate Excretorv Svstems Kidney Nephron 0 Functional unit of the vertebrate kidney 0 Each human kidney has about a million nephrons 0 Large surface area organismenvironment interface 0 Functions Filtration Reabsorption Production of concentrated urine Parts of the Nephron o Glomerulus ltration o Glomerular Nephric or Bowman s Capsule ltration o Convoluted Tubules 0 Loop of Henle crosscurrent exchange creates osmotic gradient 0 Collecting ducts Glomerulus amp Bowman s Capsule Site of Filtration steps Glomerulus is full of holes Blood pressure forces liquid portion of blood into gomeruar capsule Everything except blood cells and proteins NONSELECTIVE everything ltered OOOOO Convoluted Tubules 0 Major site of reabsorption 0 Water ions amino acids sugars etc returned to blood stream 0 Mechanism Na secondary active transport 0 SELECTIVE quotgoodquot reabsorbed quotbadquot left in ltrate Loop of Henle 0 Complex countercurrent exchanger 0 NET EFFECT creates high concentration of solutes mostly NaCl in tissues surrounding collecting ducts o This is the osmotic gradient used to concentrate urine Collecting Duct 0 Final adjustment of urine concentration 0 Dehydrated Cells of collecting duct are permeable to water Water is removed from urine by osmosis Concentrated urine produced 0 Hydrated Cells of collecting duct are impermeable to water Water stays in the urine Dilute urine produced Bladder 0 Storage organ for urine 0 In mammals NO processing of urine takes place in bladder NOTHING is absorbed from bladder BISC208 May 1st amp May 5th 2015 PowerPoint 16 Nervous System Nervous Systems Cells and Functions Neurons o Specialized cells of the nervous systems Receive information Integrate information Transmit information o Transmit information by a nerve impulse o Nerve impulses are like electricity Movement of charge 0 Nerve impulses are not like electricity Slow movement of ions not rapid movement of electrons Signal strength does not increase with distance as it does with electricity 0 Parts of a Neuron o Dendrites receive information from other neurons Cell body integration Axon transmits nerve impulses long distances Synaptic terminals release chemicals called neurotransmitters Synapse point of communication between nerve cells OOOO Neurons Resting Potential 0 Properties of a Neuron at rest no nerve impulse 0 Cell membrane has lots of active NaK pumps 0 Cell membrane at rest are IMPERMEABLE to Na ions 0 Cell membrane at rest is PERMEABLE to K ions Resting Potential Voltage charge difference 0 Cell interior is negative with respect to outside of cell because of K owing to the outside concentration gradient due to permeability of cell membrane K ows back into cell because the negative charge on inside K is positive and results in resting potential equivalent charges 0 High concentration of Na outside of the cell 0 High concentration of K inside of the cell 0 These are the direct consequence of the properties above HOW 0 Origin of Resting Potential 0 1 Concentration Gradients NaK pump uses ATP and produces concentration gradients by Pumping Na outside of the cell against a concentration gradient 0 High Na outside 0 Pumping K inside the cell against a concentration gradient 0 High K inside 0 2 Charge Gradient Na does not move because membrane is impermeable to Na K diffuses OUT of the cell because of high concentration of K inside Cell interior becomes negative due to loss of positive charges K K moves into cell attracted by negative charge Two opposing currents movement of charge Outward K current due to concentration gradient Inward K current due to charge gradient Resting Potential charge difference 0 When these two currents balance the cell is at its resting potential steady state 0 usually about 60mV Neurons Nerve Impulse Nerve lmpulse o Sudden change in membrane voltage 0 First suddenly more positive 0 Then suddenly more negative 0 Called ACTION POTIENTAL Action Voltage 0 Comparison with electricity 0 Both are movement of charge 0 Electrical signals get weaker with distance nerve impulses do not 0 Electrical signals vary in strength nerve impulses do not allor none 0 Voltage Gated Ion Channels 0 Special ion channels located in cell membranes of neurons and muscle cells 0 Open and close in response to changes in voltages Voltagegated Na channels 0 Open and close guickly Voltagegated K channels 0 Open and close slowly 0 Origin of Action Potential 0 Arrival of information from a sense organ or another nerve changes the membrane voltage of a nerve cell 0 Two changes Depolarizing toward zero 0 More positive 0 Triggers an Action Potential by causing o Voltagegated Na channels to open 0 Voltagegated K channels to open Hyperpolarizing away from zero 0 More negative 0 Step 1 Rising Phase Triggered by depolarizing voltage toward zero makes cell more positive VG Na channels open immediately 0 Massive in ux of Na into cell because of 0 Concentration gradient high Na outside 0 Charge gradient negative interior of cell Sudden positive change in membrane potential as Na charges enter the cell VG K channels just beginning to open 0 Do not have much effect 0 Step 2 Falling Phase Na channels rapidly close Now positive interior of cell no longer holds K inside Rapid movement of K out of the cell 0 Concentration gradient high K inside 0 Charge gradient negative exterior of cells attracts positive ions 0 Open voltagegated K channels speeds this process Sudden negative change in membrane potential as K leaves the cell 0 Step 3 Reestablishing Resting Phase Departure of K reestablishes negative charge on inside ofceH Cell enters the same steady state it was in before the Action Potential Balanced inward and outward currents of K NaK pump works to restore ion distribution across the membrane K channels close membrane still permeable to K o Propagation of Nerve Impulse A stimulus causes depolarization of one part of the membrane Voltagegated Na channels open Na ows into the cell Na diffuses to adjacent parts of the membrane and causes depolarization More voltagegated Na channels open Repeat down the axon Voltagegated ion channels open sequentially in a wave from one end of the axon to the other Change appears to move from one end of axon to the other but nothing actually moves that far 0 Just sequential opening of VG channels Allor none No decrement in signal strength BISC208 May 5th 2015 amp May 8th 2015 PowerPoint 17 Nervous Systems Synapses Neurons Synapse Action potential propagates down axon One way ow of information o Arrives a synaptic terminal Communicates with other neurons at the Synapse How do nerve cells communicate At contact points called Synapses where neurotransmitters are released Parts of a synapse o Synaptic terminal 0 Synaptic cleft o Postsynaptic membrane Synaptic terminals 0 Contain vesicles lled with neurotransmitters Chemical signals sent to adjacent cells at synapse Postsynaptic membrane 0 Membrane of receiving cell 0 Contain receptors for neurotransmitter Synapse Function 0 1 Arrival of Action Potential at synapse causes Voltagegated Ca channels to open Ca enters the cell due to charge gradient Ca causes vesicles to fuse with outside membrane of synaptic terminal 0 2 Neurotransmitter released into synaptic cleft by exocytosis 3 Neurotransmitter diffuses across the synaptic cleft o 4 Neurotransmitter binds to receptors on postsynaptic membrane 0 5 Most receptors are ion channels that open to cause voltage changes in the membrane of the post synaptic cell 0 o How do nerve cells communicate 0 Integration Each nerve cell receives thousands of synaptic inputs simultaneously Different synapses can cause positive or negative changes in voltage depolarizing or hyperpolarizing O The cell integrates Sums all the voltages If the voltage reaches threshold 50mv an action potential is produced Sums all arriving action potentials into open 0 Each neuron continuously asks Are summed voltages strong enough to trigger the Voltage Gated Na channels to open Purkinje Cell Largest cell in the brain 0 How complicated is the human brain O 0000 100 billion neurons Each individual neuron receives on average 7000 synapses A three year old child has about 1015 synapses A college student has 100 to 500 trillion synapses Integration of synaptic input voltages occurs billions of times per second constantly in our brains BISC208 PowerPoint 19 Population Ecology May 8th 2015 amp May 12th 2015 Ecology Ecology Study of the interactions of organisms with their environments biology o Environmentalism Activism to preserve the natural state of the environment and its ability to sustain life including humans Politics 0 Ecology informs environmentalism but should not be confused with it 0 Levels of Analysis 0 Behavioral Ecology Individual organism 0 Population Ecology Single species 0 Community Ecology Multiple species 0 Ecosystem Ecology Living and Nonliving Systems Pobulation Ecoloqv How do populations of single species interact with their environments 0 What about the environment determines Where species occur How many individuals there are How population size changes over time Pobulation Structure Patterns in Space and Time 0 Population all the individuals of a single species in a given area 0 Population density Number of individuals per unit of area 0 Pattern of Distribution 0 Uniform random or clumped Determined by 0 How they interact attract repel neutral 0 Distribution of underlying critical resources Pobulation Dvnamics Chandes over time Populations change over time due to o Births deaths immigration and emigration Population is stable when 0 Births Deaths 0 Immigration Emigration 0 Adding factors equal to decreasing factors Patterns of Population Growth 0 In an unlimited environment aII biological populations grow exponentially growth rate increases as population grows Potentially powerful force o A single pair of house ies could produce trillions of offspring in one year Exponential Growth Equation 0 ANAt rmaxN 0 Used to calculate growth rate at a given time t o N population size 0 ANAt Rate of population grown change in N per unit change in time t o rmx intrinsic maximum rate of population growth Birth rate death rate when growth is unlimited rmax is a species speci c constant ANAt increases as population size gets larger 0 In real environment populations cannot grow exponentially for long For example resources run out Growth slows as 0 Birth rate decreases andor 0 Death rate increases 0 Growth slows as population reaches its limit because birth rate decreases and death rate increases Carrying Capacity maximum population size for given environment 0 Determined by Availability of resources 0 Anything directly used by an organism causing population growth ex Food shelter 0 Availability is reduced when it is used Disease Predators 0 Growth patterns in limited environments are logistic not exponenUaH Logistic Growth Equation rmaxNK39NK Adds new term to exponential growth equations KNK 0 K carry capacity of the environment numbers of individuals Carrying capacity has little effect when N is small 0 KNK is nearly KOK OR KK or 10 0 Growth is nearly exponential at small N 0 Growth stops as carrying capacity is reached NK o ANAt approaches zero as N approaches K o KKK is 0K or zero 0 Growth stops at K ANIAt 0 Limiting Resources Carrying capacity is determined by limiting resources o In a simple stable environment each population has ONLY ONE limiting resource Essentially each resource sets a different carrying capacity K Whichever K is reached rst sets the limit 0 Example Enough food for 500 deer Enough shelter for 1000 deer If the population reaches 2000 Result 500 deer because ght over food not shelter Organism compete for limiting resources but not for other resources 0 Adding a resource effects population size ONLY when it is the limiting resource 00 Population Regulation 0 Population size is regulated by a combination of two mechanisms 0 Densitydependent As populations approach carrying capacity a limiting resource reduces population size 0 DensityIndependent Outside forces reduce population size independent of population size Fires frost storms Type of Population Regulation affects Life History Tradeoffs A species life history describes how resources are allocated among 0 Growth 0 Maintenance immunity repair etc o Reproduction Life history traits are results of tradeoffs in how an animal allocates its resources Allocation to one reduces the other 0 For example survival maintenance and reproduction cannot both be maximized Allocation strategies in uences Life span Time of rst reproduction Number of offspring Size of offspring Amount of parental care OOOOO Variation in Life History 0 High investment in reproduction o Shortlived 0 Early reproduction 0 Many small young 0 Frequent reproduction o No parental care 0 Maximizes guantity of young because of densityindependent population regulation 0 High investment in maintenance 0 Longlived Late reproduction Few large young Infrequent reproduction Intensive parental care Maximizes quality of young because of densitydependent population regulation OOOOO BISC208 Powerpoint 20 Community Ecology 1 Interactions Among Species May 12 2015 amp May 15 2015 Types of Ecological Interactions among Species Competition PredatorPrey ParasiteHost Mutualism Commensalism o Amensalism Resource 0 Anything directly used by an organism causing population growth 0 Availability is reduced when it is used Competition Organisms using the same limiting resources 0 May be intraspecific or interspecific Two types 0 Exploitative organisms compete by the rate of using resources One organism tries to consume them faster 0 Interference organisms compete by preventing other organisms from using resources Usually involves ghting or other negative effects 0 Plant Example 0 Plants compete for light through interference competition Try to overgrow and shade each other shoot competition 0 Plants compete for water by exploitative competition Try to remove more water from soil than competitors root competition Competition Seeking and Using Scare Resources Competitive Exclusion o In simple stable environments only a single species can exist on a given limiting resource 0 A better competitor excludes a species from otherwise suitable habitat Competition may restrict species ranges What determines where a species occurs 0 Physical requirements Biotic Interactions competition predation or disease 0 Ecological Niche the set of environmental conditions required by a species 0 Fundamental Niche environment in which a species CAN exist based on physical requirements 0 Realized Niche environment in which a species DOES exist because of further restrictions imposed by biotic interactions 0 Experiment on Different Species of Barnacles Observation Different species of barnacles restricted to different zones Hypotheses o H1 The species are restricted by their physical requirements o H2 The species are restricted by competition for space oExperiment o 1 Remove both species by scraping them off the rock o 2 Keep removing that species o 3 Can the other species settle once the competitor is removed oResult 0 Upper species YES settles in lower zone o Lower species NO cannot settle in upper zone Conclusions 0 Ubber soecies Chthamaus 1 is excluded from lower zones by competition 2 occupies a realized niche smaller than its fundamental niche 0 Lower species Baanus 1 excluded from upper zones by physical requirements 2 occupies a realized niche similar to its fundamental niche In simple stable environments only a single species can exist on a given limiting resource In more complex environments species using similar resources coexist because 0 spatial and temporal complexity 0 multiple resources only partially shared 0 populations are often below carrying capacity BISC208 May 15th 2015 Powerpoint 21 Community Ecology 2 PredatorPrey amp HostParasite Interactions Predators 0 Typically larger than their prey 0 Live outside the bodies of their prey Parasites 0 Smaller than their hosts 0 Live inside or outside their bodies 0 Live in a host for many generations with killing them 0 Presence of a predator has a strong effect on prey population Hypotheses Lynx and hares are in a predator prey cycle Hares and vegetation are in a predatoryprey cycle Lynx merely track Hare populations Experiment 0 Build large enclosures in Canadian Arctic Manipulate 0 Presence of Lynx o Abundance of Hare good 0 Determine of Hare populations Predictions H1 Lynx and hares are in a predator prey cycle 0 Prediction Absence of lynx will release Hare population even when food not added H2 Hares and vegetation are in a predatorprey cycle 0 Prediction Addition of food will release Hare population even when lynx present Results LOOK AT Predator Prey Interactions Predators are a strong force of natural selection Prey with the best antipredator adaptations leave the most offspring Prey have evolved many defenses o toxic hairs and bristles o tough spines 0 noxious chemicals 0 Unpalatable compounds make them taste bad to predators Antipredator Defenses are costly some organisms quotcheatquot by mimicry mimics get bene ts but do not pay costs Mimicry resemble a dangerous organism Batesian mimicry harmless species mimics a poisonous or dangerous one Miillerian mimicry two dangerous species mimic each other predators earn quicker PredatoryPrey Interactions Plants Chemical defenses against herbivores are common in plants Acute Toxins disrupt herbivore metabolism 0 Examples Nicotine interferes with the transmission of nerve impulses Hallucinogens Poisons Digestibilityreducing Compounds make plant tissue difficult to digest 0 Example tannins bind proteins and make them hard for herbivore to digest Neutral and Bene cial lnterspeci c Interactions o Mutualism both species bene t 0 Commensalism one species bene ts and one is unaffected o Amensalism one species harmed and one is unaffected BISC 208 Review Questions Discuss the advantages and disadvantages of secretion and ltrationreabsorption kidneys Why can small animals get away with secretion kidneys but nearly all large animals have ltrationreabsorption kidneys Secretion kidneys have one step take less energy and toxins are left in the blood Filtrationreabsorption kidneys have two steps take more energy and an advantage is that all toxins are excreted Small animals get away with secretion kidneys because they can use diffusion If you are dehydrated your kidney produces urine that is more concentrated than blood This seems to imply that the kidney is moving water against a concentration gradient from the urine where water concentration is low concentrated to the blood where water concentration is high dilute What process is usually used to move substances against a concentration gradient Is the process your kidney uses If not what process does it use and why You usually use active transport to move substances against a concentration gradient but the kidney uses osmosis because water molecules are too small to partake in active transport What are the ve major divisions of the kidney nephron What are the speci c functions of each Where does ltration occur Where does reabsorption occur Where is the water concentration of the urine adjusted and how The ve major divisions are the glomerulus glomerular capsule converted tubules loop of henle and collecting ducts The glomerulus and glomerular capsule are the sites of ltration the converted tubules are the major sites of reabsorption and the loop of henle is creates a high concentration of solutes surrounding the collecting ducts the collecting ducts are where urine concentration is adjusted based on dehydration or hydration Contrast the state of the epithelial cells lining the collecting duct of the nephron when you are hydrated and when you are dehydrated What changes about them to help retain or excrete water The epithelial cells are permeable to water when you are hydrated and concentrated urine is produced They are impermeable to water when you are dehydrated and diluted urine is produced What are the main parts of the neuron and what are their functions The main parts of the neuron are the dendrites cell body axon synapse and synaptic terminals The dendrites receive information from other neurons The cell body is the site of integration The axon transmits nerve over long distances The synapses are the point of communication between nerve cells The synaptic terminals release chemicals called neurotransmitters Describe the resting properties of the neuron with respect to permeability of the membrane to K and Na ions the charge difference across the membrane the distribution of K and Na ions across the membrane and the state of the voltagegated ion channels When the neuron is resting the membrane is impermeable to Na ions and permeable to K ions The inside has a negative charge high concentration of K and the outside has a positive charge high concentration of Na The K ions are owing out because of concentration gradient but they also owing in because of the charge gradient The K voltage gated ion channels are open and Na are closed Describe the steps in establishing the resting potential In particular be sure to understand how the charge difference across the membrane and the difference in K concentration across the membrane are maintained even though the membrane is permeable to K The NaK pumps use ATP to pump Na out and K in The low concentration of K on the outside makes K ions ow out of the cell and because of the now negative charge on the inside of the cell the K ows back into the cell Na does not move because the cell membrane is impermeable to Na What is a nerve impulse How is it similar to electricity and how is it different A nerve impulse is a sudden change in membrane voltage It s similar to electricity because both are a movement of charge but electrical signals get weaker with distances and nerve impulses do not Electrical signals also have various strengths while nerve impulses do not What is the role of the voltagegated ion channels in the action potential Where does the energy come from to move ions across the membrane during the action potential Where is ATP used The voltage gated ion channels open and close in response to changes in voltage The energy comes from a stimulus that causes depolarizations ATP is used to open the NaK channels in the rst place Describe what happens during the rising and falling phases of the action potential What ions are moving in and out and why When are the voltage gated ion channels open and closed What terminates the rising phase of the action potential What terminates the falling phase In the rising phase which is triggered by depolarizing voltage towards zero Na channels open immediately and Na moves into the cell because of negative charge and concentration gradient K channels begin to open slowly During the falling phase Na channels close rapidly K moves out of the cell because of concentration gradient and charge gradient The Na and K are open during the rising phase only the K channels are open during the falling phase When the channels close this terminates the rising phase and when the cell establishes negative charge on the inside this terminates the falling phase How is a nerve impulse propagated down an axon Why is there no decrement decrease in the strength of the signal from one end of the axon to the other A nerve impulse is propagated down an axon when depolarization causes Na channels open Na ows into the cell and diffuses to parts of the membrane and cause more depolarization and more channels open There is no decrease in the strength of the signal because it is an all or nothing deal Describe how a synapse works What are the steps after a nerve impulse arrives that cause neurotransmitter to be released The action potential at a synapse causes voltage gated Ca channels to open and Ca enters the cell due to charge gradients and this causes vesicles to fuse with outside membrane of synaptic terminal What happens to the neurotransmitter after it is released What actions does it have and how are those actions terminated After the neurotransmitter is released it diffuses across the synaptic cleft and binds to receptors on the postsynaptic membrane The action is terminated when enzymes break them down and they are reabsorbed by the cell What are the different patterns of distribution of organisms in space What does knowing the dispersion pattern tell you The different patterns of distributions are uniform clumped and random Knowing the pattern can tell you how they interact and how their resources have been distributed What is the equation that describes exponential growth What do the variables mean rmaxN N represents population size rmax represents intrinsic maximum rate of population growth and is a constant ANAt represents the rate of population growth How does logistic growth differ from exponential growth Which is more realistic What is carrying capacity Logistic growth is different from exponential growth because exponential growth is for unlimited environments and logistic growth is for limited environments Logistic growth is more realistic because as populations reach their limit birth rate decreases death rate will increase Carrying capacity is the maximum population size for a given environment What is the equation for logistic growth What do the variables mean Explain mathematically why logistic growth is similar to exponential growth at low population sizes but slows down as the population gets larger rmaxNK39NK ANAt represents the population growth rate rmx represents the maximum rate of population growth and is a constant N represents the population size K represents the carrying capacity of the environment When N population size is really small K NK is basically KK or 1 so it is nearly exponential Explain why most populations have only one limiting resource In the experiment described in class why did the rst addition of nitrogen have no effect but the second one caused the population to grow Most populations have only one limiting resource because every resource sets a different carrying capacity The rst addition of nitrogen had no effect because nitrogen was not the limiting resource Contrast density dependent and density independent population regulation In density dependent regulation a limiting resource reduces population size as populations approach carrying capacity In density independent regulation outside forces reduce population size regardless of the size Describe the suite of life history traits an organism would have if it makes high investment in reproduction high investment in maintenance or a high investment in growth High investment in reproduction shortlived early reproduction many small young frequent reproduction no parental care maximizes quantity of young High investment in maintenance long lived late reproduction few large young infrequent reproduction lots of parental care maximizes quality of young What types of life history traits are favored in populations regulated by densitydependent factors By density independent factors Populations regulated by density independent factors are likely to be short lived frequent reproduction many young and no parental care Populations regulated by density independent factors are likely to be long lived infrequent reproduction few young lots of parental care Is is possible for an organism to maximize its growth and reproduction at the same time Cite two examples used in lecture No this is not possible because high population comes with low growth For example ies produce many small young but they do not live long De ne predation competition mutualism amensalism and commensalism Predation when one species bene ts and the other doesn t Competition when both species do not bene t Mutualism when both species bene t Amensalism when one species is harmed and the other is unaffected Commensalism one species bene ts and the other is unaffected Why is atmospheric oxygen not considered a resource It is not because it is not something that can be limited What is the difference between exploitative and interference competition Give examples of both in plants and animals Exploitative competition is when organisms compete by the rate of using resources Interference competition is when organisms compete but preventing other organisms from using resources Exploitative ex Try to eat faster than another Animals Try to outgrow each other and shade the other Plants Interference ex Fight for food steal food Animals Try to grow more roots to soak up more water in the same pot Plants What is the difference between fundamental and realized niche How do they compare in size if you were to map them Fundamental niche is an environment in which a species can exist based on physical requirements Realized niche is an environment in which a species does exist because of further restrictions imposed by biotic interactions The realized niche is always smaller or equal in size to the fundamental niche Explain the original hypothesis for the lynxhare predator prey cycle What experiments were done to test this hypothesis Did the result support the original hypothesis The original hypothesis was they lynx and hares were in a predator prey cycle or that hares and vegetation were in a predator prey cycle Experiments that were done Manipulated presence of Lynx abundance of hare food and determined how hare populations were affected What is the difference between a predator and a parasite A predator is larger and lives outside of its prey Parasites are smaller than their hosts can live inside or outside their bodies and can live in their host for many generations without killing them Why is mimicry favored by natural selection What is the difference between Mullerian and Batesian mimicy Give examples of each Mimicry is favored by natural selection because mimics get bene ts but do not pay costs Batesian mimicry is when a harmless species mimics a poisonous or dangerous one Ex when Moths look like Bees Mullerian mimicry is when two dangerous species mimic each other Ex Poisonous butter ies In one type of mimicry the model of the mimic bene ts from being mimicked whereas in the other type of mimicry the model is harmed by being mimicked Explain n Batesian mimicry the model is harmed by being mimicked because predators eat both poisonous and harmless species In Mullerian the model bene ts from being mimicked because the predator will learn faster that they are harmful
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