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Flashcards in Photosynthesis Deck (14)
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1

Phosphorylation

light energy is converted by an organism's photosystems to ATP phosphate bond energy

(light energy boost being used to drive synthesis of ATP)

2

Calvin Cycle

importation of CO2 into a carbohydrate (in the stroma) by a eukaryotic photosynthesizing organism

3

3CO2 + 6NADPH + 9ATP -->

glyceraldehyde-3-phosphate + 6NADP+ + 9ADP + 8Pi

- this is whole equation doubled for a hexose molecule!

4

Three phases of the calvin cycle

1. Carbon Fixation
2. Reduction
3. Regeneration

5

Carbon Fixation

the mechanism by which inorganic CO2 is incorporated into organic molecules

- carboxylation of ribulose-1,5-bp to form 2 glycerinate-3-p

6

Carboxylation in carbon fixation

carboxylates ribulose-1,5-bisphosphate into two glyerate-3-p molecules

7

C3 plants

plants that produce glycerinate-3-p as the first stable product of photosynthesis

8

Major regulatory enzyme in carboxylation

rubisco

9

Reduction

glycerate-3-p is phosphorylated by ATP to form glycerate-1,3-BP

this glycerinate-1,3-BP is then reduced by NADPH to form glyceraldehyde-3-P

10

Regeneration

the production of three ribulose-1,5-bisphosphate at the expense of five of the six glyceraldehyde-3-p molecules also at the expense of 3 ATP molecules

11

examples of light activated reactions (direct)

ribulose-1,5-bisphosphate carboxylase
NADP+-glyceraldehyde dehydrogenase

12

examples of light deactivated reactions (direct)

phosphofructokinase
glucose-6-P dehydrogenase

13

indirect mechanisms

pH: during the light rxn, protons are pumped out of stroma and increases the pH

Mg2+: light increases the stromal concentration of MG2+, which is required for activity of some enzymes

14

Ribulose-1,5-bisphosphate carboxylase enzyme

genes encoding for this are located in the chlorophast (L subunit) and the nucleus (S subunit) & are activated by light intensity to form L8S8 holoenzymes in the chloroplast