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L1: BioChem: Evolution - Coggle Diagram
L1: BioChem: Evolution
SECTION 1
Evolution, the unity of all life on Earth.
The evidence for early life 3.8-2.1 billion years ago
Microfossil evidence for eukaryotic life is rare until about 850 million years ago
. The oldest convincing cyanobacterial microfossils are 2.7 billion years old but other candidates for microfossils are known from 3.3, 3.46 and 3.49 billion-year old rocks.
Biomarker molecules like steranes (eukaryotic origin) and hopanes (bacterial origin) that can only be made by living cells offer alternative biochemical evidence for life. The discovery of 2.7 billion-year old steranes that must be made with oxygen by eukaryotes caused quite a stir.
Carbon Isotopes due to the "isotope effect" in early Photosynthesis
The next evidence for early life is fossil stromatolites dated at 3.43 billion years old.
banded iron formations (BIF)
Ice Age & Biomarkers
. The 2.7 billion-year steranes would be too old if oxygen was not available for their synthesis.
The ~2.2 billion-year Makganyene (Mak-han-yee-nee) “snowball Earth” global glaciation may have been caused by the evolution of cyanobacteria with photosystem II producing oxygen that depleted methane (a green-house gas) from the atmosphere [slide 8].
The appearance of oxygen in the atmosphere is called the Great Oxidation Event (GOE).
“The GOE is probably the most fundamental transformation in the history of the planet, aside from the origin of life itself,” [Arizona State geochemist Ariel Anbar].
Large colonial fossils have been found in 2.1 Gyr deposits [slide 9]. These colonial organisms are large enough (cm size) to require an oxygenated environment.
Oxygen concentration has not always been what it is today. In the carboniferous period 350-300 MYA oxygen went to 35% allowing insects like dragonflies to grow to giant size
SECTION 2:
Ribosomal RNA and the tree of life
SECTION 3
The RNA world.
SECTION 4
The Last Universal Common Ancestor (LUCA)
SECTION 5
The origin of Eukaryotes:
Gram Bacteria
Creation
endosymbiosis or descent from a gram positive-like bacterium ancestor (neomuran)?
Differentiation into Positive & Negative
Gram negative bacteria may be the result of the endosymbiosis of an Actinobacterium and a Clostridium
Eukaryotes
Earliest Classifications
The newest eukaryotic trees
SECTION 6
Phylogenomics: the intersection of evolution and genomics.
SECTION 7
COGs and KOGs: Clusters of orthologous groups in prokaryotes and eukaryotes.
SECTION 8
A TIMELINE FOR MAJOR EVENTS IN THE HISTORY OF LIFE ON EARTH
3.5 billion years
2.7 billion years
3.7 billion years:
Date unknown save prior to 2.3 billion years
~2.3 billion years
Sometime after 3.8 billion years, but before 3.7 billion years
3.8 billion years
2.3 billion years
2.1 billion years
4.5 billion years: Planet earth forms.
4.0 billion years:
1.5 billion years
1.5 billion years
1.2 billion years
555 million years
543 million years
420 million years
380 million years
360 million years
310 million years
150-200 million years
All this Come from The Lexture 1 Evolution Word Document on your helios Computer Baely