1Timeline to the Oxygen Revolution
1) Protocells(Origin of Life) ~4 BYA
2) Bacteria ~3.8 BYA
3) Archea ~3.7 BYA
4) Photosynthetic Bacteria ~3.5 BYA
5) First Eukrayotes ~2.7 BYA
6) Oxygen Revolution ~2.2 BYA
2Protocells to Bacteria
- Hadean Eon led to possibility of protocells ~4 BYA
- Prokaryotic (most ikely bacterial domain) ~ 3.8 BYA
- Conditions were anaerobic on Earth
3Archaea
- thought to arise slightly after Bacteria ~3.7 BYA
4Anaerobic Bacterial Photosynthesis
- Beginning of anaerobic bacterial photosynthesis ~3.2 BYA
- Aquifex is an example of a living fossil. It has a cyclic photosynthesis and is an extremophile growing at 95C
5Ancient Photosynthetic Bacteria (Aerobic)
- Stromatolite fossil
- North Pole, Australia, 3.5-3.0 BYA
- Constructed by Cyanobacteria
- AKA "blue-green algae"
6Eukaryotes
- Beginning of more complex life ~2.7 BYA
- Eukaryotes can be considered a single branch of the Asgard archaea
7Domains of Life
1) Bacteria
2) Archaea
3) Eukarya
8Key featurs of Prokaryotic Cells
9Key features of Eukaryotic Cells (Animal vs. Plant cells)
10Common features for both Prokaryotic and Eukarytic cell types
11Endosymbiotic Theory: The Origin of Mitochondria and Chloroplasts
-Explains the origin of eukaryote cells including the organelles starting as a symbiotic relationship between cells of varying types that ultimately resulted in engulfing one of th eorganisms into the other.
12Photosynthesis and Oxygen
-No oxygen early because there was no source. Oxygen is highly reactive.
- Development of oxygenic or non-cyclic photosynthesis led to slow increase of oxygen present in the atmosphere
- Detect oxygen by presence of iron an dsulfer oxidized compounds (seen in fossil deposits)
13Banded Iron Formations
- O2 levels in the atmosphere slowly increased
- Originally only .000001% (1ppm)
- When O2 reached ~15% of atmosphere, reacted with iron to form iron oxides
- Layers of iron oxide 1000s of m thick deposited on bottom of oceans 2 BYA
- Aerobic respiration became dominant form of metabolism amongst Bacteria
- Anaerobes retreated to marginal enviornments
14Chloroplast
- Chromosome: Circular DNA
- Ribosome synthesize its own proteins
- Grows divides, an dduplicates its own DNA
- Eukaryotic cell withought chloroplasts cannot make chloroplasts
- Synthesizes ATP using light energy (photosynthesis)
15Major Evolutionary Events
1) Snowball Earth 800-600 MYA
2) Ediacaran 600-540 MYA
3) Cambrian explosion 540 MYA
4) Colonization of Land 360 MYA
5) Permian Extinction 250 MYA
6) Cretaceous Extinction 65 MYA