GEOSCI 100 Lecture Notes - Lecture 21: Cyanobacteria, Stromatolite, Goldilocks Principle
9 May 2018
School
Department
Course
Professor
4-12-18
Geobiology
Photosynthesizing bacteria: Save the day continued
Review:
*The Goldilocks Principle - the earth is just enough far away from the sun and has the right
type of atmosphere to have life exist
- Ex. just enough carbon dioxide Lecture Slideshow Slide #4
•How did we end up with so much oxygen and so little
carbon dioxide? (compared to Mars & Venus)
→ this happened because photosynthesis happened on
our planet
*Cyanobacteria - “blue” bacteria
- Blue-green algae
- Architect of earth’s atmosphere
•The History of Atmospheric Oxygen - tells us
something about the history of life on our planet
- Oxygen levels have changed → increased overtime
How do we know the history?
*Sources - provides oxygen through photosynthesis
- Analogy: the faucet of a bathtub
- If the source is faster and the sink gets “clogged,” then oxygen builds up
*Sinks - removes oxygen Lecture Slideshow Slide #7
- Analogy: the drain of a bathtub
- if the sink is faster than the source
than it won’t build up or
accumulate
*Ancient Stromatolites - a calcareous
mound built up of layers of
lime-secreting cyanobacteria and trapped
sediment
Document Summary
*the goldilocks principle - the earth is just enough far away from the sun and has the right type of atmosphere to have life exist. Lecture slideshow slide #4: how did we end up with so much oxygen and so little carbon dioxide? (compared to mars & venus) This happened because photosynthesis happened on our planet. Architect of earth"s atmosphere: the history of atmospheric oxygen - tells us something about the history of life on our planet. Oxygen levels have changed increased overtime. If the source is faster and the sink gets clogged, then oxygen builds up. Analogy: the drain of a bathtub if the sink is faster than the source than it won"t build up or accumulate. *ancient stromatolites - a calcareous mound built up of layers of lime-secreting cyanobacteria and trapped sediment. Oldest one of confirmed microbial origin = 2. 72 ga. *3 equations for understanding the history of atmospheric co2.
