Mol380 L10 Summary (Evolution) PDF

Lecture 10 > - microbial evolution hydrothermal vents- supplied building blocks for the 1stling organisms...

Lecture 10 > - microbial evolution hydrothermal vents- supplied building blocks for the 1stling organisms (non membrane bound (deep underwater) RNA world => genetic material replication I + catalyst of its own very versatile binds ATP , NADH DNA came next more stable than RNA handoff proteins optimized a evolutionary 3 billion Yes ago => 1st phototrophs emerged - relled on hydrogen sulfide for photosynth. Cyanobacteria = 1st microbes great oxidation event=> all the Oz released from oxygenic photosynth. anoxic World > 1 OXIC world led to total remodelling of the atmosphere. O2 levels skyrocketed · Or reacted spontaneously wh reduced iron = forming Iron oxides laminated secumentary rocks they precipitated I formed banded > - Iron formations - · pared the way for respiration => optimal yield of ATP energy (likely a allowedfordevelopme · creation of the Ozone layer : protect from harmful or radiation Carl Wrest => assembled + ever universal tree of life Using URNA (based on nucleotide seg Similarity. be shared a (Phylogenetic) ribosomal RNA genet matena was necessary It is commonly - - Established presence of 3 domains of life : Bacteria , Archaea , Eukarya Li - diverged diverged from first (23 7 bil archaea (-1 2-2 7 bil) LUCA last universal common ancestor... : to have archata thought genes shared by all cells (including RNA) must have been Got nearly engulfed - a bacterium present in LUCA EndosymbioticHypothesis Mitochondria = drose from stable incorporation of an aerobic respiring bacterium into the cutoplasm of early evkamotic cells · were previously freely existing bacteria (alphaproteobacteria) · endosymblosis was a win-win agreement easy Mitochondra was now membrane-protected and provided access to all cellular resources and cell had enhanced respiration eukaryotic now energy production I Chloroplasts => also have endosymbiotic origin drose from stable incorporation of cyanobacteric-like cell into Cytoplasm of a eukaryotic cell already containing a mitochondrion led to eukaryotic photosynthesis · Evidence : physiology , metabolism , genome structures/sequences so many similarities btwn these features of bacteria compared to mitochon , and Chloroph. · have their own circular DNA  & 2 : mechanisms of evolution natural selection => mutations occur by chance's environment selects for advantages survival of microbes who posess the beneficial mutations > - more likely to reproduce ↳ these strains ultimately pass down this genome genetic drift => change in frequency of an allels population due to random sampling of organisms (not due to differences In fitness) · most powerful in small populations and those experiencing "botherech" events bottreck events : severe reduction in population size followed by regrowth from remaining cells new traits can evolve quickly in microorganisms !!! ↳ (LTEE) term evolution experiment - example of experimental E Coli evolution started in 1988 Long - In. · grow E Coli. in minimal glucose media - represents an adaptive environment in which E coli. grow/ evolve · Dramatic increase in fitness over 1st 500 generations (then slowed down - mutation in 1/12 of the lines has allowed for the E. Coli to Utilize Citrate as a carbon source for energy production Catrate was present as a pH buffer - NOT originally considered a carbon source for E. Coli) > - the other cells lacking the mutation did not survive tool in genomics as a revolutionary evolutionary/phylogenetic studies : to tract back and determine functions of diff genes · using sequences · Phylogeny : piecing together the origins/history of life HOW ? ① sequencing genomes ② sequence assemble > - Annotations (using Brainformatics) sifting through sequences to identify genes creating genetic map Phylogentic trees depict evolutionary history => sequence changes can be used as a "molecular · nodes + branches clock" to estimate the time since 2 lineages ↓ ↓ diverged her= branchenag BUT there are some major assumptions numbeages "That , · nucleotide changes that branch to time - accumulate in proportion - are generally neutral (don't confer functional change) - are random => genome Size tells lot us a · (I. e. parastic/endosymbiotic bacteria have tiny genomes massive genomes reflect complex multicellular genomes (Introns are major contributors to big genome size) URNA = commonly used to make trees · 8 variable regions of small ribosomal subunits - can be amplified , sequenced analyzed used to related are to one another see how closely organisms - of entire genes -> allows evolution to "experiment" w/ one copy while preserving the Duplications original version Horizontal gene transfer - can complicate the reconstruction of trees  group activity : identify pair ④realeateby nd s ③ determine the pairwise diffs. WILEAST # of diffs ① align = S1) 11 I S ACAACG S2) GACAAG Sl S1/53 S1/S332 53) ACAAAG 53 S2 su) CCAAGG Su ⑤ is add to tree find - next close relationship -- 5 S · 553 54 ↓ S2