bootcamp bio photosynthesis

basic formula of photocynthesis

6CO2 + 6H2O <=> C6H12O6 + 6O2 (glucose + O2)

is photosynthesis endergonic/exergonic, spont/nonspont?

endergonic + nonspontaneous (takes in energy to build a new molec)

which part of the leaf is the major site for photosynthesis ?

palisade mesophyll

which part of the chloroplast is the site for the Calvin cycle?

stroma

where does light dependent reaction take place ?

thylakoid

purpose of light dependent reaction?

provide ATP + NADPH for light independent reaction

purpose of light independent reaction? (aka calvin cycle)

fix carbons to make glucose

basic steps of noncyclic photophosphorylation?

1) photolysis = light energy splits water

2) e-s excited and enter first ETC

3) e-s go thru redox rxns and more protons are pumped from stroma to lumen

4) e-s reach PSI and get excited again + enter 2nd ETC

5) NAP+ reductase reduces NAP+ to NADPH

6) protons accumulate in lumen and form electrochemical gradient , ATP synthase uses proton flow to produce ATP

what happens in cyclic photophosphorlyation?

PSI passes e-s back to 1st ETC (makes a loop bw two) which results in ATP production (NO NADPH production)

(more ATP made here than noncyclic )

basic 4 steps of light independent rxn (calvin cycle)

1) Carbon fixation

2) Reduction

3) Regeneration

4) carbohydrate synthesis

what goes on in carbon fixation

Rubisco (king of elements) combines CO2 + 5C RuBP to make 6carbon comp . this comp splits into two 3C PGA molecs

what happens in reduction, regeneration, and carbohydrate synthesis?

reduction = PGA molecs phosphorylates by ATP and reduced by NADPH to make G3P

regenration = most G3P used to make more Rubp

carbohydrate synthesis = some of that G3P used to make glucose

what is the problem with regular photosynthesis? (c3)

photorespiration (C2 photosyntehsis) → rubisco can also react w O2 which gives PGA but also a 2C molec called phosphoglycolate . u need to shuttle this molec thru peroxisomes and mitochondria to convert to PGA which wastes energy and fixed carbons, so the net benefit of photosynthesis is lost ☹

what are adaptations that plants have used to overcome C2 photosynthesis (photorsporation)?

C4 photosynthesis and CAM photosynthesis

how does C4 photosynthesis avoid photorespiration?

by utilizing spatial isolation: takes CO2 and moves it to a diff space in the lead which makes it more efficient

1) PEP carboxylase fixes CO2 to 3C molec PEP which makes 4C oxaloacetate . this gets converted to malate.

2) malate transferred to bundle sheath cells (decr O2)

3) malate decarboxylated to form CO2 and pyruvate (CO2 then gets fixed by rubisco to undergo Calvin cycle and pyruvate converted back to PEP)

Ex of C4 photosynthesis: CORN

how does CAM photosynthesis avoid photorespiration?

by utilizing temporal isolation:

1) stomata closed during day to prevent transpiration (water evap)

2) stomata open during night where CO2 is stored as malate in the vacuoles

3) during the day, malate is decarboxylated to release CO2 for photosynthesis and pyruvate is converted back to PEP

Ex of CAM photosynthesis: CACTUS , PINEAPPLES