Lecture 13

Question 1

What are the two stages of Photosynthesis? What do they involve

Answer 1

1. Light Reactions - thylakoids help to capture light.

2. To ‘fix’ CO2 in sugar with ATP and NADH. (Stroma)

Question 2

Which pigments are involved within the light harvesting complexes?

Answer 2

Chlorophyll A & B

Question 3

What are the steps at each light photosystem 2 complex to capture light energy?

Answer 3

1. Spitting of H2O in the special chlorophyll (a or b) in Photosystem II. Forms O2 and H+ and electrons
2. Photons from the sun will excite the electrons to a higher energy state.
3. Transfer of the electrons to the primary electron receptor.

Question 4

What are steps that happen just after Photosystem 2 and linking to photosystem 1? (End to chemiosmosis) What 2 components are needed for the dark reactions?

Answer 4

1. Electrons that are transfered to the primary electron receptors lose their energy to drive the Cytochrome Complex to pump the H+ agains the concentration gradient
2. Remaining electrons will then re-excitied by photons in Photosystem I, and used via NADP+ Reductase to convert NADP+ –> NADPH.
3. Normal Chemiosmosis will occur to form ATP
4. NADPH and ATP is then used and carried to the dark reactions.

Question 5

What are the main names of the steps of the Calvin Cycle?

Answer 5

Carbon Fixation
Reduction
Regeneration of CO2 acceptor

Question 6

What are the Steps of the Calvin Cycle?

Answer 6

1. 3CO2 is added to a 3x 5C, a reaction catalysed by the enzyme Rubisco.
2. The 3x 6C is formed and quickly broken down the 6x 3C.
3. The use of 6ATP and 6NADPH will undergo reduction and form the 5x 3C and the 1 G3P molecule (1x 3C). The G3P molecule is used to form glucose and other compounds
4. The 5 x 3C molecules then uses 3ATP to produce 3x 5C which is the regeneration of the CO2 acceptor.