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Honors Environmental Science Week 17 pt 2
Terms in this set (25)
Last universal common ancestor. If we trace all evolutionary lineages back to some point, there would be some organism that is the ancestor to all of the others
Some examples of organic molecules?
proteins, nucleic acids
How could organic molecules potentially become complex organic molecules
Organic molecules adhered to clay minerals, which provided the structure needed for the substances to organize. The clays, along with their metal cations, kickstarted the chemical reactions that caused the molecules to form polymers. The first RNA fragments could also have come together on ancient clays.
provide structure needd for substances to organize
What is E. coli?
a primitve prokaryote that may resmeble the earliest cells
For an organic molecule to be come a cell...
it must be able to separate itself from its environment
How were the first cells formed?
to separate itself from it's environment - lipid membrane grew around organic material. Eventually molecules could make their own organic material and replicate themselves
What were the earliest cells?
Prokaryotes. They all have a cell membrane, but lack cell nucleus and other organelles. W/o a nuclus, RNA was lose in cell, overtime cells became more complex
Luca was a...
prokaryote. Different from first living cells because its genetic code was based on DNA
Oldest fossils are
tiny microbe like objects 3.5 bill yrs old. E
first single celled life forms. Evidence for it goes back 3.5 bill years
Earliest life forms could not...
photosynthesize. They most likely absorbed nutrients that floated around in the organic soup that surrounded them. after mill of yrs these nutrients would have become less abundant
when did photosynthesis begin?
around 3 bill yr ago, 1.5 yrs after earth was formed
what did photosynthesis do?
allowed organisms to use sunlight & inorganic mocoules (like carbon dio and water) to create chemical nrg for food
A cell needs chloroplasts
to photo synthesize
Importance of photosynthesis
1. allowed organisms to create food nrg to sthey didn't rely on nutrients around in environment, and become food for others
2. oxygen. anaerobic adapted organisms gas was toxic and they died out
organisms that completely changed the progression of life to anaerobic to aerobic
How long have cyan bacteria exists?
present 2.8 bill yr ago, may have been back as early as 3.5
Archaen was when
cyano bacteria were the dominant life form.
Why were cyanobacteria dominant in precambrian?
Many lived in stramatlites
reef like structures. They continued on into the cambrian but their numbers declined
What is modern cyan bacteria called?
blue-green algae. May consist of 1 cell or many and are found in many diff environment.
How much photosyntthesis do cyanobacteria do?
20-30% of photosynthesis on earth
How do you categorize eukaroyotes?
When did Eukaryotes evolve?
about 2 billion years ago
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