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Week 11
Origin of life + evolution
| Question | Answer |
|---|---|
| LUCA | last common universal ancestor; not the first living organism but the one that gave rise to the lineage of all current living organisms |
| Evidence of LUCA (biochemical features shared by all living organisms) | same 20 amino acids in the same configuration (L); all have DNA + RNA; all use ATP as energy currency + same genetic code |
| Early formation + conditions of earth | solar system/earth formed by condensation of rocks + dust around the sun; water is vaporized; earth was hot + steamy with small oceans; H2. CH4, SH2, NH3 present, O2 not |
| First stage of hypothesis of origin of life | powered by lightning + UV rays, organic mooecules form in the oceans "prebiotic" or "primordial soup" |
| Miller + Urey expirament in reducing atmosphere | to test if organic molecules could form spontaneously on early earth; reducing atomosphere (no O2); energy electrodes simulate lighting; heated -> ocean; produced amino acids/organ. compounds + proved abiotic synthesis of lifes building blocks is possible |
| Which atmosphere resulted in a higher rate of abiotic synthesis? (volcanic or reducing) | volcanic becuase higher concentration of sulfer + CO2 leading to higher production of amino acids |
| Second stage of hypothesis of origin of life | Polymerization reactions reactions in clay produce the first macromolecules |
| Formation of first macromolcules | nucleotides are attracted to charged clay particles; as prebiotic ponds evaportate mucleotide concen. increases leading to more collisions favoring dehydration synthesis; heat from sun/volcanoes provide energy... |
| Formation of first macromolcules pt. 2 | Mineral ions act as abiotic catalysts accelerating the synthesis of nucleic acid polymers and other biological macromolecules -> the clay provided the perfect envirometn to transform monomers into nucleic acids/proteins etc. |
| Third stage of hypothesis of origin of life | Macromolecules become enclosed in a membrane + protocells forms |
| Protocell definition | membrane bound precursers to true living cells; lipids + other organic molecules naturally organize into bilayer vesicles when added to water |
| Selective permeability (vesicles) | allows for the concentration of specific molecules like RNA inside the vesicle |
| Simple reproduction (vesicles) | vesicles can increase in size + divide into smaller daughter vesicles |
| Energy gradients (vesicles) | can maintain a membrane potential (voltage) which is fundemental for modern cellular metabolism |
| Fourth stage of hypothesis of origin of life | Some protocells absorb RNA molecules that can self-replicate -> then the first prokaryotes appear |
| How + why was RNA the first genentic material catalyst | some RNa molecules can adapt a variety of shapes/structues; some can bind to other molecules + chemically transform them; some can self-replicate |
| What is the oxygen relvoltion? (O2 coming into atomsphere) | caused by the activity of photosynthic bacteria + evolution of chloroplasts in photosynthetic eukaryotes; consequences are extinction of many prokaryotes species + emergence of aerobic metabolism |
| Origin of eukaryotes/endosymbiont hypothesis | infolding of the plasma membrane in the ancestral prokaryote originated in the endomembrane system; engulfment of aerobic heterotrophic prokary. + endosymbiosis originated mitochondria; photosynthetic prokary -> plastid/chloroplast |
| Evidence of origin of eukaryotes | both chloroplasts/mitochondria contain single circular DNA molecule in their inner compartments; their ribosomes are similar to those in prokary. then eukary' they reproduce similarly to prokary. reproduction; sim. size to bacteria; double membrane |
| Macroevolution definition (broad) | descent with modification - current species are descendents from ancestoral species which were different from the current ones |
| Microevolution defintion (narrow) | changes in the genetic composition of a population from one generation to the next |
| Charles Darwin's observations/inferences | there are variations among individuals in a pop; organisms produce more offspring then the enviroment can support; individuals with advantageous traits will survive + reproduce more + those favorable traits will become more frequent in the pop. |
| Relative fitness definition | Contribution of one individual to the gene pool of the next generation relative to the contribution of other individuals |
| Adaption definition | determined trait that allows for better survivial + reproduction. ex. diff beak shapes on galapagos finches to better suit their unique diets |
| Homology definition | similarities in structure between species due to shared ancestry; but diff functions in diff. organisms |
| Molecular homology definition | similarities in the structure of molecules between species due to shared ancestry (the longer 2 species evolve on their own, the greater the # of genetic differences that accumulate) |
| Sources of genetic variation | crossing over + independent assortment (meiosis), random fertilization + mutations |
| Mechanisms of evolution | genetic drift (chance-natural disaster/bottleneck events), natural selection + gene flow (migration) |
| Darwins postulates pt. 1 | 1. the individual organisms that make up a population very in the traits that they possess + 2. some of the traits are heritable |
| Darwins postulates pt. 2 | 3. survival/reproductive success are highly variable (more offspring are produced that survive...) + 4. indivs. with certain heritable traits are more likely to survive/reproduce |
| Chili plant example | variation is present in pop; variation is inherited; some survuve + reproduce more (is not random. ex mice like less spicy pepper better) -> the composition of the population changes from 1 generation to the next |
| Antibiotic resistance meaning | bacteria evolve to survive/evade being killed by antibiotics; slowly rendering them more and more ineffective |
| Natural selection changes popualtions not individuals | acclimatization does not equal adaptation; natural selection just sorts existing varients among individuals it doesnt change them |
| Evolution is not goal orientated | they do not occur bc organisms want/need them; mutations occur by chance; loss of traits cans be adaptive; there is no such thing as a higher or lower organism |
| Evolution does not produce "perfect organisms" | not all traits are adaptive; some traits cant be optimized due to fitness trade offs + some traits are limited by genetic historical or enviromental contraints |
| 6 examples that demonstrate that humans are not evolutionarily perfect | infection-prone appendix; too many teeth; poorly adjusted vertebral column for bipedalism; goosebumps; big heads/narrow birth canal + injury prone not useful coccyx (tailbone) |
| Soapberry bug example | bugs had longer beak for rounder bigger fruit but then smaller flatter fruits got introduced + by 40 years later they had evolved a shorter beak |
Created by:
every_august
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