photosynthesis…life’s basic rx! basic questions some history some plant anatomy some...
Post on 19-Dec-2015
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Photosynthesis…life’s basic Rx!
Basic questionsSome historySome plant anatomySome biochemistry light reactions dark reactions photolysis
Basic questions??
What do plants eat?Why do plants need light?Why do plants need water?Why are plants green?
Some History…Greeks to …?“what do plants eat”?VanHelmont’s tree…Priestly & phlogiston…Lavoisier lost his head over some O2…well?Englemann & bacteria?Melvin Calvin 1948!
Summary of photosynthesis ???CO2, H2O and light go in…Carbohydrate and O2 come out
6CO2+6H2O
C6H12O6+O2
Anatomy of a leaf
Function(s)??Collect sunlightMake ‘food’Move food to storageThus…Structure related to function…
Summary of the chloroplast
Double membranesThylakoid disks called grana (chlorophyll)
StromaETS‘loose’ enzymes
2 sets of photosynthetic reactions
Light dependentLight energy captured3 reactions
Light independentCalvin cycleMakes pyruvate (C3)
QUIZ
Why are leaves green?Relate chloroplast to mitochondriaWhat is chlorophyll?What cell organelle contains chlorophyll?
How is light ‘captured’?
How to ‘grab’ a photon?
How to ‘hold onto’ the ‘hot potato’ (energy of photon)
3 light dependent reactions
Photosystem I…cyclic photophosphorylation
Photosystem II…noncyclic photophosphorylation
photolysis
The Light Reactions (light dependent)
Cyclic Photo-phosphorylation (photosystem I)Noncyclic Photo-phosphorylation (photosystem II)Photolysis
Cyclic photophosphorylation
Photon ‘excites’ e-e- ‘absorbed’e- passed thru ETSATP generated via chemiosmosise- ‘recycled’
Quiz
What’s produced in photo I?How is ATP made?What happens to the electron?
ATP
Chemiosmosisrecycled
Quiz: photosystem II + photolysis
What is made?
How is ATP made?
What is the importance of O2?
ATP, NADPH, O2
Chemisosmosis
Free oxygen released thus changing the world…why??
Products of light reactions
ATP (via chemiosmosis)NADPHOxygenWhat happens to these? And…What about night?
What happens during ‘dark’ Rx (light independent reactions)
CO2 from air is ‘fixed’…ATP & NADPH carry energy from light RxC3…pyruvate (PGA) is formed2X ‘turns’=C6…?C6>organic ‘stuff’
Quiz-Dark reactions (Calvin cycle)
Why are these reactions called ‘dark’What are the products of the Calvin cycle?Where in the chloroplast do these Rx occur?What kinds of molecules can be made from PGAL (pyruvate)?What is the most prevalent protein on the planet? Why is it so important?
Alternative pathways??
Why is the former called C3pathway?photorespiration…?C4…CAMNot as efficient as C3 but, hey….beats nothing?