L4: Evolution of microbial life Flashcards
What is the speculated composition of the atmsophere - elemental
e- donor: H2S, H2
CH4 (methane)
NH4 (ammonium)
CO
H20
What is the speculated compostion of atmosphere - larger scale
- volcanic activity
- standing oceans
- a lot of metals
- no oxygen
- no organc compound
What is primordial soup
buch of molecules floating
What was the Urey Miller Exp
when u add energy to primodrial soup … organic compounds form
What are coacervates, how?
in liquid liquid phase seperation macromolecules aggregate to minimise macro/H2O interactions => which makes coacervates (early floating molecules)
How do cacervates behave
they can grow if more molecules are added and divide when stress is applied
What does the RNA hypothesis suggest
RNA performed informational and catalystic roles that DNA now does. Life became more compartmentalised and RNA produced DNA which is more stable
Why did metabolism evolve
developing more pathways to produce more compounds that can be used and are available
What are the steps in RNA => DNA
- RNA makes inorganic molecules
- RNA self replicated
- RNA makes proteins that allow for membraner formation and changes in chemistry
- RNA codes DNA + protein
- DNA takes over
Last ancestor was
autotroph
LUCA lithotroph or organotroph
lithotroph
Luca chemotroph or phototroph
both were available, but there might have been UV before sunlight so maybe chemotroph
What were the 2 luca criteria. What did these help to explain away
- present in at least 2 higher taxa of bacteria + archea
- must recover bacterial + archeal monophyl
Helped to explain away HGT cus if it happended archea would look more like bacteria
Describe LUCA
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
Where did LUCA live and why
hydrothermal vent
- acidic = natural PMF
- lots of transtion metals
- salty water = Na
- lots of H2
What are main remenants of LUCA physiology still present today. Why important
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
What were problems encountered when sequencing LUCA
- HGT
- LUCA was a community and not a single totipotent species
What does genomic analysis support in division of archaea vs bacteria
- origin of the domain is rooted in divergence of WL pathway from
* LBCA as actogen
* LACA methanogen
What is the earliest evidence for life
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
What is an early example of oxygenic photosytnthesis
banded iron formations, no longer form cause oxygen exists
What was the great oxidation event, caviat
- 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
What was the origin of life hypothesis
serial endosymbiosis where pre-eukaryote engulfed mitochondria bacteria endosymbiant.
- happended due to survivial as O2 became available. heterotrophic aneorbic enguled aerobe
What are the two competing theories of endosymbiosis
- nucleus first: proks dont have a nucleus so pre-euk had it then ate mitchondria then ate chloroplast
- mitochondria first
What was the great swallower
Asgard
Why is eukaryotic cells metabolically limited, redeeming
- 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
