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MICR450 > L4: Evolution of microbial life > Flashcards

L4: Evolution of microbial life Flashcards

1
Q

What is the speculated composition of the atmsophere - elemental

A

e- donor: H2S, H2
CH4 (methane)
NH4 (ammonium)
CO
H20

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2
Q

What is the speculated compostion of atmosphere - larger scale

A
  • volcanic activity
  • standing oceans
  • a lot of metals
  • no oxygen
  • no organc compound
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3
Q

What is primordial soup

A

buch of molecules floating

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4
Q

What was the Urey Miller Exp

A

when u add energy to primodrial soup … organic compounds form

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5
Q

What are coacervates, how?

A

in liquid liquid phase seperation macromolecules aggregate to minimise macro/H2O interactions => which makes coacervates (early floating molecules)

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6
Q

How do cacervates behave

A

they can grow if more molecules are added and divide when stress is applied

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7
Q

What does the RNA hypothesis suggest

A

RNA performed informational and catalystic roles that DNA now does. Life became more compartmentalised and RNA produced DNA which is more stable

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8
Q

Why did metabolism evolve

A

developing more pathways to produce more compounds that can be used and are available

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9
Q

What are the steps in RNA => DNA

A
  1. RNA makes inorganic molecules
  2. RNA self replicated
  3. RNA makes proteins that allow for membraner formation and changes in chemistry
  4. RNA codes DNA + protein
  5. DNA takes over
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10
Q

Last ancestor was

A

autotroph

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11
Q

LUCA lithotroph or organotroph

A

lithotroph

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12
Q

Luca chemotroph or phototroph

A

both were available, but there might have been UV before sunlight so maybe chemotroph

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13
Q

What were the 2 luca criteria. What did these help to explain away

A
  1. present in at least 2 higher taxa of bacteria + archea
  2. must recover bacterial + archeal monophyl
    Helped to explain away HGT cus if it happended archea would look more like bacteria
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14
Q

Describe LUCA

A

Pathway: Wood-L using H2 or H2S as e- donor
enzymes: CODH/ACS
cofactors: NADPH, MoCo
Energy: encoded Na proton antipoter (Na out, H in)
Encoded: nitrgoen fixation to make it’s own
Genetic Code: had DNA

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15
Q

Where did LUCA live and why

A

hydrothermal vent
- acidic = natural PMF
- lots of transtion metals
- salty water = Na
- lots of H2

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16
Q

What are main remenants of LUCA physiology still present today. Why important

A

nitrogen fixation +
WL pathway: makes CO2 which is available for biosynthetic reaction however the Calvin Cycle only make glucose. There was no need to break down glucose meanng catabolic processes evolved in reverse as anabolic processes

17
Q

What were problems encountered when sequencing LUCA

A
  1. HGT
  2. LUCA was a community and not a single totipotent species
18
Q

What does genomic analysis support in division of archaea vs bacteria

A
  1. origin of the domain is rooted in divergence of WL pathway from
    * LBCA as actogen
    * LACA methanogen
19
Q

What is the earliest evidence for life

A

Stromatolies where
1. cyanobacteria grow in a biofil and create layers
2. the sediment deposit on top of the biofilm and minerals precipate which causes a layer
3. the cells go to the surface for more light

20
Q

What is an early example of oxygenic photosytnthesis

A

banded iron formations, no longer form cause oxygen exists

21
Q

What was the great oxidation event, caviat

A
  • a dramatic increase in atmospheric oxygen.
  • delay cus oxygenic photosythnthesis evolved earlier but oxygen was slowley accumilating but did not reach levels where they could escape
22
Q

What was the origin of life hypothesis

A

serial endosymbiosis where pre-eukaryote engulfed mitochondria bacteria endosymbiant.
- happended due to survivial as O2 became available. heterotrophic aneorbic enguled aerobe

23
Q

What are the two competing theories of endosymbiosis

A
  1. nucleus first: proks dont have a nucleus so pre-euk had it then ate mitchondria then ate chloroplast
  2. mitochondria first
24
Q

What was the great swallower

A

Asgard

25
Q

Why is eukaryotic cells metabolically limited, redeeming

A
  • they arose from one archeal group that engulfed one bacteria group meaning there are metabolically limited. Most eukaroyotes are
  • … obligate aerobes
  • … use EMP
  • … use Oxygenic Z + C cycle
  • … are chemo organo hetero
    Reedemer: many mitochondra

MICR450 (17 decks)

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