Bio2 Exam 2 Study Guide
Bio2 Exam 2 Study Guide BIOL 10513
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This 12 page Study Guide was uploaded by Sijil Patel on Wednesday March 30, 2016. The Study Guide belongs to BIOL 10513 at Texas Christian University taught by Dr. Demarest in Spring 2016. Since its upload, it has received 128 views. For similar materials see Introductory Biology II in Biology at Texas Christian University.
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Date Created: 03/30/16
Week 7: Animals -most animals we know of are insects Phylum Porifera -2 layers of cells (inner and outer layer) separated by matric coated over skeleton made of CaCO3, SiO2, or sponging spicules -no symmetry, circulatory system, reproductive organs, etc. -phagocytsosis (intracellular digestion) -barely multicellular -NO TRUE TISSUES -cells can redifferentiate -beating flagella (choanocytes) move ater into channels where food is trapped -cell coordination via calcium signaling -Sponges use voltage gated Ca+ channels to communicate -sponge larvae have sensory cells that allow them to detect/react to environmental stimuli Innovation: 1) voltage gated Ca+ channels voltage gated Na+ channels somewhere along the animal line (not in sponges 2) voltage gated Na+ channels made possible electrically excitable cells: muscles and nerves Voltage-gated Na+ -amino acid charges interact with charges along membrane, channels influencing the protein’s shape -when membrane depolarizes, the ionic change causes the amino acids to shift, distorting the channel enough to open it Neural action -signals cause Na+ to open at affected synapses potential -if enough of them open, depolarization of axon hillock occurs -this leads to wave of opening voltage-gated Na+ channels (=action potential) -depolarization at axon terminal triggers a release of neurotransmitter -rapid (2 m/s) electrical communication over long distances -myelination can increase the rate ~50X through salutatory propagation Chemoreceptors Smell, taste Mechanoreceptors Touch, hearing, balance Electromagnetic -Photoreceptors (sight) receptors -Electroreceptors (electricity) -Magnetoreceptors (magnetic fields) -Thermoreceptors (temperature) Nociceptors Sense pain Sensing intensity -Perceive greater intensity= more intense stimulus can cause a neuron to fire more frequently -Perceive greater intensity= more intense stimulus may recruit a greater number of neurons in a nerve to fire Temporal More frequent stimulation makes a neuron more likely to fire, and summation more frequently -receiving excitatory neurotransmitter at a synapse more frequently heightens the strength and duration of depolarization of that synapse -more likely for sufficient depolarization to reach axon hillock and fire action potential Spatial summation Multiple sensory neurons feeding into single interneuron make it more likely for the interneuron to fire -receiving excitatory neurotransmitter at multiple synapses similarly heightens the depolarization -more likely for sufficient depolarization to reach the axon hillock and fire the action potential Sensory (neural) Eventually neurons may stop sensing intensity adaptation -due in some modes to sensory neuron running out of vesicles carrying neurotransmitter (synaptic fatigue) Sensing Direction -timing when different neuron signals reach brain -interplay of neuron inputs (excitatory vs inhibitory) help brain identify source of stimuli Ex: most intensely firing neron at center of touch contact (highest level of stimulus) Ex: mechanoreceptor excites central neuron, but inhibits neurons in surrounding area to help brain identify point of contact Light sensitive spot Path of light sensitive cells allow for sensing of light v dark -pigment backing in cells allows for some sensing of light direction Very simple eye Light sensitive spot turned into a cup to allow for directional information Single lens eye Ability to focus all light to one spot= higher acuity Compound eye Mosaic of individual images Squid Eye Focusing: lens moves forward and back Photon Passage: sensory neurons are in front of the other neurons and blood vessels in the retina Human Eye Focusing: lends is warped by ciliary muscles Photon passage: sensory neurons are behind other neurons and blood vessels in retina (light must pass through to small unclutter spot on retina called fovea (needs blood), optic nerve has to pass back through=blind spot) “backwards” -protection against heat from brighter light mammalian retina -absorbed light generates heat in choroid layer behind retina (better to have photoreceptors further forward, away from heat source) -fish have same inverted retina structure -terrestrial gastropods have retinas like cephalopods -no better blood flow to support metabolic demands -better visual acuity -cephalopods appear to be on par with fish and bird -acuity seem to be more function of photoreceptor density and wiring Eye Evolution -eyes hare underlying unity in genes 1) opsins- used by all animals -light sensitive proteins with chromophores 2) crystallins- found in all lenses, derived from stree-protectice proteins -protein in all lenses Vertebrate Vision -photons of light strike opsin proteins in retinal photoreceptor neurons Rods- sensitive to photons = black and white vision (work well in dim light, more abundant in periphery of retina, peripheral vision more sensitive to light) Cones- less (1/100) sensitive but respond to certain wavelengths (short, middle, long=blue, green, red) for color vision (provide color information, need 100x more light, concentrated in center of retina, we see color better at center -photon impact causes photoreceptor to hyperpolarize rather than depolarize: backwards of other sensory neurons 1) photoreceptors don’t fire action potentials, at rest they are immediately polarized (-35mV due to constantly leaking Na+ and constantly releasing neurotransmitter glutamate) 2) Photons of light activate opsin pigments in a photoreceptor (retinal: light absorbing part of opsin changes conformation when hit) 3) Activated opsins activate a G-protein signal cascade that leads to closing of Na+ channels in photoreceptor 4) Closing Na+ channels hyperpolarizes the neuron (to -70mv) so tit turns completely off (stops releasing glutamate) 5) Decrease in glutamate either allows (stops blocking) or inhibits (stops exciting) various bipolar cells, amacrine cells, and horizontal cells to fire 6) serves to integrate the info passed to ganglia, which passes the neuron activation pattern the brain 7) we see light Synaptic fatigue -makes us feel dizzy after we stop spinning -impacts vision, but bc vision is backwards (neuron off= sight) not in a straightforward way Impact on Vision: -if neurons always on and releasing glutamate, then why don’t they undergo this and make us see light flashes? -firing rate low and they release only a little glutamate -some fatigue in vision is possible due to activation in certain bipolar cells in the light Troxler’s fading and -optical illusion affecting afterimages afterimages -stimulus away from fixation point fades away and disappears -peripheral vision affected most -fewer photoreceptors there Afterimage Mechanism: -rods and cones in retina -rods sensitive to light and dark -cones sensitive to color -when exposed to certain hue for a long time, they become fatigues Nervous System -senses and passes impuld -interpret neuron pater and coordinate response Cnidarian nervous system: -like sponges, two layers of cells with jelly matix -true tissues with much stronger multicellular organization -digest extracellularly -diffuse neural network coordinates muscle activity: simple nerve net -simple signal transmit response: signal passes in cobweb of interneurons Bilaterian Nervous -axons of neurons bundled into nerves System -neurons on and off but nerve modulated by what fraction is firing -cell bodies of interneurons group into ganglia (receive inputs, allow for sophisticated response) -nerves and ganglia group into peripheral/central nervous system Brain and sensory -brain coordinates and interprets multiple inputs into single intergration cohesive product -helps survive and reproduce Animal Movement -nerves get stimuli and processing centers interpret and direct response -nerves signal muscle response and muscle contraction driven via action potential Skeletons and -skeletons anchor muscle and transit motion Movement -hydroskeleton: muscle and water pressure work together for shape/movement (muscle contract in ring around coelom) -endo/exoskeleton- hard structures inside/outside the body -bivalves (2 hinged shells) -Arthropods( molt) -mammals (cartilage and bones) Week 8: Homeostasis Homeostasis -“standing the same” -maintenance of constant internal conditions -without it, biological processes are disrupted Regulate: -temperature -cell size/number -Ions (pH) -sugar -urea -water -O2 and CO2 2 Main Strategies: -conformity or regulator Mechanisms: passive, behavioral biochemical -there is ALWAYS a negative feedback loop ( action taken to reverse the trend) -can also have feedforward regulation (anticipation for something) or positive feed back (outcome amplifies process) Conformity simply allow the given internal variable to match that of the external environment Reuglator actively set and maintain the given internal variable at a value consistently different from that of the external environment Endotherms more regulator in strategy; primarily utilize physiological mechanisms to maintain a highly constant internal body temperature Ectotherms more conformer in strategy; primarily utilize behavioral means (if any) to maintain a somewhat constant internal body temperature Homeostatic processes -at level of cell, tissue and organ (organism as whole) -receptor or sensor monitors environment, controller acts as control center and effector carries out response Nervous system Main homeostatic controller (vertebrates) -monitors internal and external environment -brain is homeostatic controller Endocrine system Along with NS, coordinate homeostasis, sugar -chemical messaging -hypothalmic pituitary axis (sends tropic hormone to pituitary) -3 kinds of hormones: peptides, amines, steroids -slower longer lasting response -2 forms of signal amplification: glandular cross talk (endocrine axes) where tropic hormone stimulate production other hormones OR signal transduction pathway Immune system Health -2 components: innate and adaptive -innate is broad protection with physical and cellular defense -wbc’s and eosinophils and basophils (important to recognize invaders) -inflammation can be good to help fight but bad if anaphylaxis induced -adaptive immune system involves lymphocytes -T cells: carry antigen recognizing molecules (cytotoxic killer and helper and memory) Circulatory system Nutrients, temperature, O2 and CO2 -rapidly distributes materials throughout animal body -Cnidarians and flatworms do NOT have a circulatory system -cells close to surface, nutrients mix in GVC, enter/exit via diffusion -Network of cylindrical vessels: arteries, veins, capillaries -pump: heart -Open system (no veins): ostia -insects: organs bathed in hymolymph inside hemocoel cavity -heart sloshes it around (low pressure, transport, control) -closed system (veins/arteries): valves -circulating fluid separate from rest of body Closed Ciculatory -arteries: blood away from heart System -arterioles: small artery branch leading to capillary -capillaries: smallest blood vessels, feed oxygenated blood to tissues, feed deoxygenated blood from tissues into veins -venule: moves deoxygenate blood from capillaries to veins -veins: carry blood toward heart Vertebrates: -single heart with chambers -blood oxygenated via diffusion across respiratory surface and deoxygenated via diffusion out of the various body capillaries -arteries have multiple elastic layers with collage/elastin to hand high pressure pulse -veins have valves to prevent low pressure backflow Countercurrent -system where exchange takes place bw two fluids w Exchange -which are flowing in opposite directions (heat, gases and chemicals can be transferred) -useful to preserve steep gradients -prevents severe heat loss (pelican foot example) -arteries transfer their heat to nearby veins instead of to environment when blood reaches skin surfaces Respiratory System O2 and CO2 Animal Respiration -O2 from water/air enters by diffusion into cells -thin animal cells achieve respiration via direct contact (sponges, cnidarians, flatworms) -thicker animals require structures (tracheae, lungs, air sacs, gills) Earthworms: -no specialized organ, moist thing and highly vascular skin -oxygen diffuses across skin body cavity blood in dorsal blood vessel Insects: -ventilation -respiratory apparatus with spiracle and trachea -cas exchange via diffusion or pumping air into tubes -tracheal system delivers oxygen right to muscle cell, without hemolymph flow (very active) Lungs -mammals, reptiles and amphibians have these -only mammals have diaphragm -use alveoli /capillaries for gas exchange Birds: -have lungs and air sacs -unidirectional flow of air through lungs allows all air flowing through lungs to be fresh air with maximal oxygen to be collected Gills -used by fish -fills collect dissolved O2 from water and release CO2 -exchange occurs in lamellae Lymphatic system Water and waste Vertebrates: -returns interstitial plasma to blood Digestive System Nutrients Urinary system Urea and water Respiration on land Advantage: diffusion 8000 times faster Disadvantage: thin respiratory surface can desiccate Solution: use pores or actively pump fresh air in and old air out across capillary bed (tidal ventilation) Animal Metabolism Animals are exclusively chemoheterotrophic (obtain energy and carbon from organic compounds) -3 main fuels: carbs, fats, proteins Keliber’s Law -build respiration chambers to measure O2 consumption -found metabolic rate increases is smaller than mass increase (larger animals have slower metabolic rate per gram) 1) larger animal has higher percentage of relatively low maintenance reserve tissue 2) a larger animal has a lower surface area to volume ratio Week 9: Animal Digestion and intro to reproduction Energy Storage -energy from food via ATP -excess energy in carbs (to glycogen), fatty acids (to fats) and amino acids (to proteins) Nutrition -concerns ability to rapidly and consistently acquire/take in an energy source has been factor in evolution Ex: -hinged jaw in chordates allowing massive food intake -consistent access to high energy food source in large amount may have been major factor inevolution of human brain Digestion -break down of insoluble molecules into smaller, water- soluble molecules -food ingested as particles into some sort of chamber and broken down fro energy/waste removed -sponges: intracellular -most animal digestive system have same basic plan with foregut, midgut, and hindgut -systems adapt to diet (carnivores had shorter intestines, large stomachs) (herbivors have small stomach and long intestines) Cecum -fermentation chamber harboring bacteria that break down tough to digest fibers Appendix -harbors bacteria reservoir to function in immune system Soluble Wastes and -leftover bulk solid food matter is evacuated from colon Osmotic Challenges -some undesirable soluble materials make it to blood stream, (need to be filtered out) -need to manage solute concentrations (osmoregulation) Osmoconformers -adjust internal solute concentration to match that of surrounding environment to avoid water gain/loss -mussels and sharks Osmoregulators -can also use mechanisms that bring in / expel water vs ions to maintain concentration Malphigian Tubules -way to get rid of soluble wasters -place transport proteins in vessel walls to actively transport waster molecules out of blood into waste stream Insect water/waste -insects have open circulatory system management -waster products actively transported from hemolymph into malphigian tubulus along with water -tubules carry waster into gut where they mix with food -nitrogenous waste converted into uric acid -accumulation acidifies rectum, causing uric acid precipitate -no longer solute and osmolarity in rectum falls leading to water movement back into hemolymph -uric acid, feces and waste out while water reabsorbed Planarian Worm -protoephridium water/waste -beating cilia bring interstitial fluid into tube and out pore management into environment (taking waste) -cells lining tubes reabsorb good molecules and let waste go out -no circulatory or respirator ysystem so simpy use diffusion -need to get rid of lots of water anyway bc live in freshwater Earthworm water/waste -coelom filled with fluid management -fluid drawn by cilia into waste tube (like flatworm) -cells along waste tube recapture and transport good molecules out of waste stream -capillaries around waste tube reabsorb good molecules -waste unites that perform filtration followed by reabsorption and secretion are called metanephridia Vertebrate kidney -closed circulatory system and cannot dump water -best waste elimination organs 3 steps: 1) filter blood 2) reabsorb good molecules and water 3) excrete everything else -blood runs into porous capillaries that loop around into bundle glomerulus and water and solutes ooze out of capillaries leading to blood filtration) -glomerulus inside capsule that catches everything that oozes out and drains it into tube that forms Loop of Henle -tube actively recaptures good molecules and water into surrounding capillaries and takes up additional solutions out of capillaries as needed -nephron-functional unit of kidney -glomerulus + capsule and tube = nephron -many nephrons = kidney -longer loops of henle= greater opportunity for water reabsorption -adapted to meet osmotic challenges ex: -freshwater fish: dump water, retain alt, N eliminated -saltwater fish: retain water, dump salt, N eliminated -kangaroo rat: retain water, dumper super salts, N eliminated -fish kidneys mainly help in osmoregulation (cartilaginous fish do not have well developed kidneys , but accumulate urea in tissues with help of osmoregulation Sex -2 costs: need for mate and slow population growth -MAJOR advantage: genetic diversity -goal is to cut total number of chromosomes in half and bring back together to make new mixed whole (use fusion of haploid sperm with haploid egg to make diploid offspring) Genetic -chromosome/gene composition determines sex XY System -male gamete determines ex via X vs Y chromosome -Y = testes determining factor = testes develop (no Y, no TDF) -female is default XX= female XY= male X0 System -male gamete determines sex via passing on X vs no second sex chromosome= imbalance of gene expression = male XX= female X=male ZW System -reverse XY -male is homozygote ZZ -female is heterozygote ZW -female gamete determines sex ZZ= male ZW= female Haplo-diploid system -fertilized eggs are diploid and become female -unfertilized eggs stay haploid and become male unfertilized egg= haploid male; fertilized egg=diploid female Week 10: Animal Reproduction Environmental -external cues alter developmental pathway Temperature -no heteromophic sex chromosomes- sex determined by incubation dependent temperature of egg during key window in development (alligator <30 = female, >34 male) Social Interaction -sex depends on what other individuals the animal grows around Ex: -marine worms become male if larvae encounter female -reef fishes develop depending on sex around them -arthropods by infection by Wolbachia bacteria (manipulates reproduction of infected hosts) Sex Change -adults may switch sides -frequent in tropical reef fishes, female to male more common, clownfish are more rare where all are male and the dominant one becomes female (Nemo lmao) No Sex -always female or hermaphroditic Determination -all earthworms are hermaphrodites -some species reproduce exclusively by parthogenesis -some species switch bw sexual reproduction and parthogenesis (facultative parthogenesis) Sex on land -egg and sperm need to be in water to survive = external fertilization in water had to give way to internal fertilization on land External -outside body fertilization -easy oviparity: lay eggs and shoot sperm on them -less mate search -supports r- strategists -only works well in water (can’t disperse on land/dries out) Internal -inside body fertilization -improved chances of gametes connecting -more mate search -allows for oviparity on land but egg need membranous structures to not dry out and constant incubation -vivparity: internal fertilization internal development -supports k-strategists Reproduction and -most animals sexual, diploid stage dominates life Development -after sperm fertilizes egg, zygote undergoes rapid division called cleavage -this leads to formation of multicellular hollow blastula -this undergoes gastrulation, forming gastrula with different layers of embryonic tissues Protostome (mollusk, annelid, arthropod) vs Deuterostome (mouth second, echinoderms and chordates)
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