Chapter 4 - Photosynthesis

Question 1

chlorophyll

Answer 1

a green pigment located inside chloroplasts, which absorb light energy.

Resides in the thylakoid membranes

Two types of chlorophyll a

• p700 associated with photosystem I
• p680 associated with photosystem II

Question 2

Explain non-cyclic photophosphorylation

Answer 2

light energy hits p680 and photosystem II

electrons are taken from splitting water into Oxygen and two H+

The excited electrons are transferred to an ETC that transfers electrons to p700 and photosystem 1. This results in about 1.5 ATP. The electrons that were gained by water splitting replace the excited electrons.

Photosystem I gets hit by light.

It sends electrons through it’s own ETC forming NADPH from one of the H+ floating around from the water splitting. The other H+ will be used to form ATP through chemiosmosis.

Question 3

What is the overall formula for non-cyclic phosphorylation?

Answer 3

H20 + ADP + Pi + (NADP+) + light -> ATP + NADPH + O2 + H+

Question 4

What is cyclic phosphorylation?

Answer 4

The chloroplast has its own ATP production and does not use ATP from the mitochondria. If ATP gets low, the chloroplast can undergo cyclic phosphorylation.

Rather than moving down the ETC to form NADPH, the electrons move back down the first ETC to form ATP again. The primary acceptor of the second ETC for non-cyclic can also pass the electron back down the primary ETC to continuously generate ATP

Generates about 1 ATP on average