PLS 150 Lecture Notes - Lecture 6: Chlorophyll, Panspermia, Photosynthesis
29 Sep 2016
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Chapter 5: The Rise of Chlorophyll
9/28/16
Where did life come from?
• Deism? Creationism?
o Creationism: God created the Earth
• Aliens?
• Panspermia?
o Life on other planets, asteroid carrying life landed on Earth so here we are
• Evolution?
Evolution:
• For life, you need building blocks
• On Earth, carbon-based molecules (building block)
• BUT molecules are complex
o They don't just exist naturally
• Where did they come from?
o Urey-Miller: created a theory on how life on Earth happened
o this is how we think life originated on Earth
Urey Miller:
• A dozen amino acids (proteins)
• Multiple sugars
• Repeated experiments produced even more molecules
• How do we go from molecules to life?
• Some assemble spontaneously
• Major gaps still exist
• Complex molecules are not life
• Replicating molecules are not life
• Or are they? Viruses?
• Questions on early Earth atmosphere
• Considerable debate still exists as to exactly how life actually started
So now we got life...
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Document Summary
Viruses: questions on early earth atmosphere, considerable debate still exists as to exactly how life actually started. Chlorophyll spreads: cyanobacteria evolve it first, they dump o2 in the atmosphere, evolution continues in o2, cyanobacteria invade other, non photosynthetic cells, the first of the true plants come about as symbionts. Light is absorbed as photons: chlorophyll strips electron from h20, electrons are passed down etc, as electrons move, protons are pumped, differential in proton concentration drive atp/nadph2 production. Atp: atp adenosine triphosphate, often considered cell currency. It powers cellular reactions: breaking atp releases energy, nadph2 another energy sink, everything runs on atp, these are light-dependent reactions. Light-independent reactions: products from etc power reactions, a cyclic, recycling process, co2 fixed. More water used: sugars produced, called calvin cycle (also known as c3 cycle): 3 carbon cycle- some plants use c4 cycle: starts with a 4 carbon molecule.
