MEDICAL ETHICS NOTES
MEDICAL ETHICS NOTES Phil 164
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Biology 152 Exam review Take Home Important information Multicellular Evolution is not directed the drunkard s walk Organisms work with the tools they have You should be able to interpret these graphs and answer similar questions about them Distinguish between adaptation and acclimation Evolution Natural Selection Drunkards Walk A single individual acclimates to a change in situation by altering physiology not consciously A population adapts overtime to changes in situation Mutations are random polymerases are imperfect Natural selection itself is not lions gotta eat Prerequisites for evolution by natural selection A Variation in traits exists in a population B This variation must lead to differences among individuals in lifetime reproductive success fitness C variation among individuals must be genetically transmissible to the next generation What is the difference between natural selection and evolution a Evolution Through time species accumulate differences as a result descendants differ from their ancestors In this way new species arise from existing ones b Natural selection Gradual non random process by which heritable traits become more or less common in a species based on differential reproduction What does fitness mean in reference to natural selection a Organisms who most successfully pass on their genes Archae Bacteria and Eukaryotes Know similarities and differences if I give you a characteristic is the organism likely prokaryotic or eukaryotic a Similarities 1 Basic metabolism energy transduction 2 Biomolecules DNA RNA they have membranes bDifferences l 2 3 4 5 6 Size Nucleus Internal membranes Organelles Prokaryotes can live many more places more energy sources Multicellular lineages in eukaryotes What are the three domains a Archae Bacteria Eukaryotes What does LCA mean bLast Common Ancestor Multicellular Advantages Disadvantages 0 What makes it multicellular Highlighted the ones that will be present in every multicellular organism The other are often present 2 Tissues 3 Organs 7 Three dimensional organization some cells not in contact with their environment 0 Advantages 1 One of the primary advantages of multi cellularity is defense 2 A second is that they are better able to maintain their position and collect food think of kelp or cheetahs for instance 0 Disadvantages lLimits of diffusiondistribution 0 Vessels take advantage of bulk ow movement of liquids under pressure 0 Surface to Volume Ratio 0 Diffusion relies solely on concentration gradients 0 Organisms without some sort of transport system are size limited 2 Must stick together support organism 3 Cell to cell communication 4 Regulate cell division and cell fate development and reproduction 5 Defense Multi cellularity Overview 0 Cells and organisms are size limited unless they can solve the diffusion problem 0 Take home is that the toolkit to create multi cellularity eXisted before multi cellularity developed Natural selection acts upon What s there and over long periods of time which traits are conserved depends on their advantages whether the organism with the trait has more progeny Mouse and Human Glial Cells All the information necessary to make the organism is stored in the cell as DNA The mouse and human are separated by many millions of years of evolution and yet our glial cells are so similar that the human can replace the mouse cells The signals in the mouse brain are sufficient to tell human glial cell progenitors differentiate correctly The cells are different enough that the organism mouse behaves differently that difference is in the DNA So cell fate is regulated in part by external signals that are at least to some extent conserved through evolution Gene Control and Gene Development Development is controlled by signaling molecules So here is one way that multicellular organisms have met one of the big challenges signaling from cell to cell to control fate A morphogen is a substance governing the pattern of tissue development this includes the positioning of various cell types Within the tissue Development Control Hierarchical l Segmentation is conserved 2 Control of segment development is in part through a hierarchical order of genes Maternal oo ordinate genes Q l W Pair Rule genes Segment polarity genes Gap genes 1 Maternal Gap Pair rule 2 3 4 5 Segment polarity Hox 3 Ectopic expressed at the wrong time Knocked out doesn t express at all 4 Fax 6 2 rounds Segmentation 1 A fairly common evolutionary innovation in animals 2 It s not very clear in humans anymore but in early embryo this one is 22 days it s a bit more obvious as somites which develop into parts of the organism 3 In drosophila anterior posterior polarity is determined by maternally produced mRNA This is happening at the cellular blastoderm stage 4 Once anteriorposterior polarity is established different genes control the segmentation in a hierarchical pattern Each set in hierarchy is transcription factor that leads to transcription of proteins but also transcription of the next layer of regulation pair rule segment polarity etc 0 Maternal tell you anterior posterior 0 region 0 The pair rule make the segments by turning on in each one 0 The segment polarity give each segment a front and a back 5 Knocking out a level of this hierarchy disrupts formation of part of the body 6 Knockouts in these genes are almost all embryo lethal You don t get a y 7 Final step is identity of the segments This step is controlled at least in part by homeobox genes hox genes 8 Transcription factors that lead to eXpression of genes that ultimately result in a structure The HOX genes code for transcription factors that regulate gene eXpression in the embryoThey determine much of how a body looks where does a leg or a wing grow Developmental Control Combinatorial Flowers and leaves develop from the top of the plant called the apical meristem Genes control what organs develop Floral Morphology a Carpel is where the egg cells get formed b Stamen ultimately grows the pollen c The petals are well I guess you know what petals are d Sepals are the small leaf like structures at the base e They are in whorls surrounding the central aXis of the ower 0 ABC Hypothesis a A genes on their own lead to sepals m 33 3 39 39 b A B gives you petals mm we re l c B C gives you stamen male part Whom r d C alone gives you carpel female part e Also A inhibits C and C inhibits A so ip illfioes off A goes on and vice versa so If A is missing C takes it s place in each whorl determines which floral The combination of A B and C activities organs develop from that whorl Plant Physiology Adaptations to Multicellular challenges 0 Waxy cuticle l 5 Vasculature l 2 3 Stomata 1 Seeds 4 5 1 Limits of diffusior distribution 2 Must stick together support organism in part 3 Cell to cell communication 4 Regulate cell division and cell fate development and reproduction 5 Defense Plant Anatomy 0 Three types of Tissue a Dermal dissectior defense b Ground catch all photosynthesis c Vascular transport nutrients 0 Stomates a Allows CO2 in and Water vapor out b Open and close through diffusion pumps solutes into the cytosol increases internal sugar concentration c Open up depending Where they are here they open during the day dessert open during night so not too much water let out Vasculature 0 Xylem transports water made of dead cells NEGATIVE PRESSURE eX a straW 0 Phloem transports sugar and hormones live cells POSITIVE PRESSURE eX hose a Transports sugar actively into sink fruit Angiosperm Reproduction Gameophyte ln Pollen Ovum Sporophyte 2n seed Endosperm 3n fatty stuff to feel seed Seed is the embryo of a the endosperm then the seed coat maternally derived The fruit is the swollen ovary around the seed it is maternally derived Meiosis occurs in the ovum of the ower Animal Physiology Symmetry a Bilateral front back top bottom b Radial All planes Ancestral traited are shared by the taxa and includes ancestors Derived traits not shared by ancestors but present in descendants Bilateral symmetry set the stage the ventral nerve cord in many organisms This predated the neural tube that became the spinal cord ultimately Embryonic Development Germ Layers Gastrulation Formation of Germ layers leads to 2 or 3 layers a Ectoderm outer layer b Endoderm digestive respitory c Mesoderm organs skeleton muscles circulatory Segmentation Homeostasis All organisms strive to maintain a stable internal environment a pH b Solute concentration c Temperature d Glucose e Fats etc 0 Maintaining a body temperature is a struggle because organisms constantly exchange heat With the environment through four physical processes radiation evaporation convection and conduction not always at the same time 1 Radiation transfer of heat energy through the atmosphere electromagnetic radiation 2 Evaporation goes from liquid to gas uses your heat 3 Conduction direct transfer 4 Convection is essentially conduction to a moving source a uid or gas 0 Negative feedback loops 0 Negative feedback occurs When the regulatory system makes a change in the opposite direction to a change in internal conditions a The set point is the level the homeostatic system is attempting to stick to b A sensor is a structure that senses some aspect of the external or internal environment c An integrator is part of the nervous system that evaluates sensory information and quotdecidesquot if a response is necessary to achieve homeostasis d An effector is any structure that helps to restore the desired internal condition 0 Organisms use both physiological and behavioral changes to bring the system back to the set point these are effectors a Circulatory adaptations too hot increase blood to organs that can radiate heat i Countercurrent heat exchangers ii Large surface area with lots of circulation b Cooling by evaporative heat loss c Behavioral responses go hide in the shade d Adjusting metabolic heat production thermogenesis shivering e Insulation Current Exchangers 0 Crosscurrents Crossover of some property between two liquids owing next to each other in opposite directions 0 Countercurrent Crossover of some property between two liquids owing next to each other in opposite directions small gradients are maintained such as heat 0 Concurrent crossover of some property between two liquids in same direction large gradients disappear quickly such as heat Energy Requirements 0 Bigger animals with bigger masses require more energy Muscles 0 Skeletons a Hydroskeletons l The majority of animals on Earth rely on a hydrostatic skeleton one way or another ex tongue worms elephant trunks 2 Very limited for movement with large bodies b Exoskeletons 1 Key innovation in arthropod ancestor ii helped spectacular diversification iii Better protection made of chitin carbohydrate 1 Limitations i Growth must molt ii Breaks are harder to repair and can result in desiccation c Endoskeletons l Vertebrate endoskeleton bones amp joints 0 Change in angles between bones key to movement 0 Bones cartilage tendons ligaments 0 Can be repaired and grows relatively easily 0 Supports much larger organisms Types of muscles 0 Striated because of the striped patterns 0 Skeletal for movement cardiac muscle 0 Smooth digestion Actin and Myosin Actin is the thin filaments it grabs on to the myosin Myosin is the thick filament Together makes the power stroke 1 Note when bound to ATP the affinity for actin is low 2 ATP hydrolysis and the ADP Pi still attached to the myosin 3 Myosin ADPPi binds to actin it has high affinity 4 The power stroke is followed by release of ADP and Pi 5 Myosin doesn t let go until another ATP binds When the muscle contracts the thick filaments move along the thin filaments the z discs get closer together Respiration and the Gas Exchange 0 Partial Pressure and Respiration 2 The diffusion of gases works like the diffusion of solutes 3 Gases go from high concentration to low but you figure out concentration with partial pressure 4 Getting oxygen into cells relies on diffusion 5 Gas goes from where its own partial pressure is higher to where its own partial pressure is lower to try to even the concentration 6 Notice in the image the C02 coming in is way higher than atmospheric 0 Gas Exchange 1 Ventilation i Bulk ow ii Movement of gas or liquid iii Pressure 2 Diffusion i From lungs to capillaries 0 Which system is most efficient 1 Fish gills most efficient i 2 Avian lungs next most 339 Em 3 efficient 3 Human lungs least efficient however concentration is higher Circulatory Systems 1 First system is most efficient g g Nervous System 1 Central Nervous System Brain and spinal Cord a Oligodendrocytes insulators in the cns b Astrocytes provide support c OMicroglia part of the immune system in the brain 2 Peripheral Nervous System a sensory neurons running from stimulus receptors that inform the CNS of the stimuli b motor neurons running from the CNS to the muscles and glands called effectors that take action c Schwann cells Neurons l The signal goes from Electrical to chemical 2 Schwann cells cover the axon but have gaps in between called nodes of ranvier which the electrical signal jumps from signal to signal 3 Long thin non myelinated sends signals the slowest Resting Membrane Potential 0 Always negative 0 K and Cl move freely in and out of cell 0 Na is outside sodium gated channels 0 Creates a charge separation negative in inside positive on outside 0 Nernsts Potential log C 10 MD a C L E262 mV 3 1 Depolariia nn 2 Hep liarimtxien E H phase phase Action Potential 9 0 Normal membrane potential is E 4D Thre hmd Mammy about 70 gm 0 Slowly depolarizes until a am Hastli g pmm a a llllyrperpulanruzatlun phase certa1n pomt Threshold I I I 1 potential then Na channels 39339 Tim megs 393 a open and Na rushes inside of i the cell and makes it more positive rapidly depolarizing 0 After reaches a certain point Na channels shut and K rushes outside the cell to hyperpolarize 0 Goes back to normal Synapse 0 Synaptic transmission begins With action potential conduction to the axon terminal 0 Depolarization of the axon terminal opens voltage gated Ca2 channels 0 Vesicles respond by fusing With the presynaptic membrane releasing neurotransmitters into the synaptic cleft 0 Neurotransmitters bind With receptors on the postsynaptic cell 0 Some of these receptors are ionotropic let in ions and depolarize the postsynaptic membrane 0 Some of these receptors are coupled to signaling pathways called metabotropic serotonin is of this type Neurotransmitters NESESTJZ39SJEZ s 0 There are four basic types i 1043quot Neumpep des a very diverse group only two of which are shown Subrtante VF Meta k pha i n a n endurplh i n T CIy EI Phe Me N 1 it Oxide N4 b Amino acid c Monoamines dopamine norephinephrine histamin seratonin d Peptides e Other diverse like acetylcholine fThe same neurotransmitter can be excitatory in one case and inhibitory in another Evolution 0 Evolution Through time species accumulate differences as a result descendants differ from their ancestors In this way neW species arise from existing ones When speaking of evolution time means generations many of them Natural selection Gradual non random process by Which traits become more or less common in a species based on differential reproduction Artificial selection Non random process by Which traits become more or less common in a species because humans are selecting Which organisms have offspring Misconceptions About Evolution There is no intentionality no trying in natural selection An organism doesn t develop a trait in order to deal With an environmental challenge Change is random selection is not Fittest is not necessarily strongest fastest healthiest etc 0 All adaptations are not a perfect fit for the environment you work With the tools you ve got Genetic Variation a Sources 0 There is no intentionality no trying in natural selection An organism doesn t develop a trait in order to deal With an environmental challenge 0 Change is random selection is not 0 Fittest is not necessarily strongest fastest healthiest etc 0 All adaptations are a perfect fit for the environment you work With the tools you ve got Hardy Weinberg l Assumptions 0 random mating no mutation no gene ow no genetic drift infinite population size no natural selection 2p frequency of allele A 3 q 2 frequency of allele a 4 p2 2pq q2l Types of Selection Frequency of lndlv id uals 1 Evolved pupu lalionl Original population I 3939 39t 1 w c 39 D or Positive selection is for a trait a Usually positive selection Will lead to fixation of the trait b That is all of the population Will have it Negative selection against Stabilizing selection tends to reinforce a median trait this is the majority form Directional pushes to one extreme or another Disruptive selection tends to split the phenotype this can lead to speciation Convergent Evolution 0 Not an Ancestral trait 0 Things develop W similar structures in different groups Gene Flow Migration Evolution can occur because of gene ow Changes allele frequencies Increase genetic variation Within a population that receives immigrants Reduce genetic differences between populations 0 Introduce alleles that improve fitness Genetic Drift 0 Genetic drift When genetic variability is reduced because of random chance 0 Loss of allelic diversity 0 Two types of genetic drift a Bottleneck effect 1 Because of a drastic reduction in population 2 Alleles are lost 3 Think of the Chihuahua 4 Or going from population of 2000 I 20 in last slide 5 Others may be over represented b Founder effect 1 some alleles are over represented because a small starting population Speciation 0 Species are two animals that can produce fertile offspring 0 Biological Species Concept Ernst Mayer articulated the biological species concept Group of actually or potentially interbreeding natural populations Which are reproductively isolated from other groups 1 Group of actually or potentially interbreeding natural populations Which are reproductively isolated from other groups 2 Problems With BSC a Asexual species b Hybridization 0 Allopatric separated geographically 0 Sympatric not separated geographically a Allopatric speciation b Sympatric speciaiion Copyrl llllllllllllllllllll nc lllllllllll niam IIII mmings Gene Flow against Speciation 0 PreZygotic a Mechanical b Temporal c Geographical d Behavioral 0 PostZygotic a Sterile Hybrids Adaptive Radiation 0 One species moves into neW environment and over time adapts to this environment 0 This is essentially founder effect combined With disruptive selection Pholgeny 0 Nodes a Nodes show a common ancestor b May or may not be represented in the fossil record or elsewhere 0 Monophyletic group evolutionary unit that includes all of the descendants of an ancestral species but no others 0 Synapomorphy a shared derived trait that defines monophyletic groups 0 Shared traits that are not shared ancestral traits are called analogous traits They are evidence of convergent evolution Monophyletic taxon Glade Polyphyletic Groups Paraphyletic Groups WWOW 37 8 VWVV As opposed to biological and ecological Phylogenic species Concept Can use morphology and genetics classification goes through change as new information comes out Genetics for Phlogenies Non coding DNA mutates at a known rate This can be used to trace species divergence Coding DNA will mutate at a slower rate and will be affected by selection but generally organisms that have more similar DNA are more closely related Human Orgins Non coding DNA mutates at a known rate This can be used to trace species divergence Coding DNA will mutate at a slower rate and will be affected by selection but generally organisms that have more similar DNA are more closely related New World monkeys All arboreal many have prehensile tail Old World monkeys and hominids remained in Africa 1 No prehensile tails 2 Tough rump for sitting Genus Homo Homo 2 MYA Smaller teeth and gut Made tools Used fire Reduced sexual dimorphism pairing Ate meat can tell from teeth and butchering marks on bones Culture Phenotypic differences Specific changes in protein coding sequence Changes in expression levels of genes Ecology Ecology is the study of relationships of organisms to one another and the environment Includes biotic life to life Abiotic life to non life Population Growth inhabiting the same general area belonging to the same species EXponential growth MODEL If N is the population then A N will equal births deaths Population ecologists study the change in population over a given time so AN A t Even more importantly they are interested in the PER CAPITA growth rate in a particular time frame Births deathsN The rate PER CAPITA doesn t vary in this model The number of individuals at any given time varies so the slope of the curve varies So if growth is 50 and there are 500 individuals then you add 250 if you have 1000 individuals you add 500 Population limiting factors can be density independent it doesn t matter how many individuals of the population in the range Density independent variables tend to be things like drought Density Dependant Negative feedback Factors limiting population growth can also be density dependent it gets worse as the population increases In this case death rate rises as population goes up As the population of the kelp perch goes up the kelp bass eats more so death rate goes up Density dependent limitations tend to lead to uctuations around the carrying capacity Community Ecology 0 Species have different survivorship curves That is in some organisms the youngest are very susceptible to death lots of plants and baby turtles In some the death rates are evenly distributed birds and small mammals Some often survive a long time usually big animals These survivorship curves affect reproductive strategies R and K strategist Because of different life survivorships organisms put different amounts of energy into their young Two basic approaches r strategists and K strategists rstrategists make lots of young and assume many Will be eaten these are focusing on making sure that per capita rate is very high K strategists invest a great deal of energy into just a feW young usually K strategists live very close to the carrying capacity Niches The spread of one species is affected by the other Fundamental niche Usually in space but can also be temperature or time that an organism could use Realized niche the actual part of niche used because of interactions With other species Symbiosis 1 Resources are limited There is strong intra and inter specific competition 2 3 4 Species have evolved compleX inter species interactions For biologists any close interactions between two or more species that have evolved over time Antagonisic Predation Herbivory Parasitism Competition 6 Mutualistic 0 Mutualism 0 Commensalism O 7 Know Keystone species