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origin of life&evolu
biol 1210 origin of life & evolution
| Question | Answer |
|---|---|
| describe LUCA & evidence for it | Last Universal Common Ancestor - all living organisms evolved from it but LUCA was NOT 1st living organism. Evidence: same 20 amino acids in configuration L, same genetic substances DNA/RNA, same energy molecule ATP, same genetic code. |
| briefly describe earth before life | earth & solar system formed by condensation of rocks/dust around sun -> earth bombarded by debris -> water vaporized -> early Earth was hot & steamy w small oceans |
| describe a reducing atmosphere & 1st stage of origin of life | Earth cools down, H2O condenses -> reducing atmosphere is w/o O2. made of H2, CH4, SH2, NH3. All reducing agents. 1st stage: Organic molecules form in "primordial soup" ocean, powered by UV & light radiation from sun |
| describe Miller & Urey experiment in reducing atmosphere | proved that abiotic synthesis of organic molecules is possible. Used reducing atmosphere, simulated lightning energy w electrodes, simulated primitive sea w heated H2O & these conditions produced amino acids & other organics! |
| reducing v. volcanic atmosphere: which is better n why? | volcanic atmosphere results in a higher rate of abiotic synthesis due to presence of more SH2 & CO2 |
| 2nd stage of the origin of life | polymerization reactions in clay produce the 1st macromolecules from soup of monomers (amino acids, nucleotides) |
| describe how the formation of the 1st macromolecules took place | nucleotides attracted to charged clay particles -> as prebiotic ponds evaporate, nucleotide concentrations increase = more frequent molecule collisions for dehydration synthesis -> sun/volcano heat as energy -> mineral ions as catalysts for synthesis |
| 3rd stage of the origin of lfie | macromolecules become enclosed in a membrane & protocells form |
| describe protocells & how they formed abiotically | lipids & other organics naturally organize into bilayer when added to H2O. This provides selective permeability; concentration of specific molecules inside (RNA) + simple reproduction (binary fission) + energy gradient (membrane potential) = cell function |
| 4th stage of the origin of life | some protocells absorb RNA molecules that can self-replicate |
| describe RNA's role in the origin of life | RNA was the 1st genetic material & catalyst. RNA can adopt variety of shapes, structures, bind to other molecules & transform them, and self-replicate, allowing for first prokaryotes to exist |
| give brief timeline for the history of life/the earth | 4600 mya, earth formation -> 3500 mya, 1st prokaryotes -> 3000 mya, O2 revolution -> 1700 mya, 1st eukaryotes -> 600 mya, earliest animals -> 300 mya, earliest land plants -> 65 mya dinosaur extinction -> 5 mya, earliest humans |
| describe the cause & consequences of the oxygen revolution | 1st cause/spike in O2: photosynthetic bacteria, 2nd spike: evolution of chloroplasts in euk. Consequences: extinction of many anaerobic prok. & emergence of aerobic metabolism (most efficient) |
| summarize endosymbiont hypothesis | ancestral prokaryote (Archaea) is large, so infolding of membrane to increase SA -> nucleus + ER in ancestral euk., compartmentalization, large -> engulfing of ancestral heterotrophic prok. then photosynthetic prok. -> mutualism to mitochondria + plastid |
| list evidence for endosymbiont hypothesis | both mitochondria/chloroplast contain single circular DNA like prok., have ribosomes more similar to prok. than euk., reproduce independently & like prok., similar size to bacteria & double membrane from phagocytosis |
| define macroevolution | descent w modification: current species r descendants from ancestral species, which are different from current ones |
| define microevolution | a change in the genetic composition of a population from one generation to the next within the same species |
| describe Charles Darwins' observations and inferences (bonus: from what work?) | there's variation among individuals in a population + organisms produce more offspring than environment can support = individuals w certain advantageous traits survive & reproduce more -> over time, such favourable traits become more frequent in populatio |
| define relative fitness | describes the contribution of one individual to the gene pool of the next generation relative to the contribution of other individuals. Ex. 10 offspring = 10 copies of genes in pop. is bigger contribution than 5 offspring (5 copies of genes) |
| define adaptation & give example | a genetically determined trait that allows for better survival & reproduction, ex. birds whose beaks r different depending on their diet (narrow for insects, wide for seeds, etc.) |
| define homology & give example | similarities in structures btwn species due to shared ancestry/divergent evolution. Homologous structures may difer in function. Ex. due to 1 common finch ancestor, all finches have beaks, similar eye position + head shape, but beaks r different function |
| define molecular homology & give example | similarities in the structure of molecules btwn species due to shared ancestry. Ex. monkeys share 138/146 of amino acids in human hemoglobin |
| list sources of genetic variation | meiosis: crossing over & independent assortment, random fertilization & mutations |
| name & briefly describe the mechanisms of evolution. Which one(s) lead to adaptation? | natural selection (shift towards favourable traits in a population over time), gene flow (migration) & genetic drift (random events by chance) |
Created by:
AntBanana
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