Lecture 4-Chloroplast Flashcards Preview

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Flashcards in Lecture 4-Chloroplast Deck (25)
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1
Q

How often do plants replenish atmospheric content of oxygen

A

every 2000-3000 years

2
Q

Three steps of photosynth

A

photochemistry, electron transfer and production of NADPH and ATP
incorporation of CO2 into carb and production of O2

3
Q

Pigments

A

transfer radiant energy to chemical bonds, many double bonds that interact with photons

4
Q

Enzymes

A

transfer chemical energy

5
Q

Light reactions driven by photons entering chloroplast

A

2h2o>o2+4h+
3ADP+3Pi>3ATP
2NADP+ +2H+>2NADPH

6
Q

Chloroplast double membrane

A

no PS, allows passage of small compounds, water, some proteins

7
Q

Stroma

A

liquid, dark reactions

site of ATP and NADPH accumulation

8
Q

Thylakoid membrane

A

light reactions

9
Q

Thylakoid space

A

light reactions

10
Q

Thylakoids

A

site of photosystems 1 and 2

11
Q

3 Light absorbing compounds

A

chlorophylls (a and B)
Cartenoids
Phycobilins (red algae and cyanobacteria which have a and c but no b)

12
Q

Interaction between photons and double bonds of pigments depends on

A

molecular structure
length of carbon chain
number of d.b in chain
structures at end of chain

13
Q

Primary electron acceptor

A

2 chla coupled to protein, chla without magneisum

14
Q

Trap chlorophyll

A

chla and protein

15
Q

P680chl a/protein complex

A

680 nm (red light)

16
Q

P700 chl a/protein complex

A

700nm (far red light, people cannot see)

17
Q

Resting P680

A

powerful oxidant, readily accepts electron.

readily splits water, releasing protons and oxygen

18
Q

excited P680

A

excited by photons from chl a reactive centre, electrons torn from water are boosted to a higher state and passed along to another compound (pheophytin). falls back to unexcited state, cycle begins again

19
Q

Non-cyclic photophosphorylation

A

excited P680 passes e to pheophytin in Photosystem II. Pheophytin passes e to quinone.
Quinone gives to cytochrome b6/f
Passed to PSI, chla passes energy to P700.
boosted to excited state by photons. e donated to PSI which forms NADPH.
ATP and NADPH in equal amounts. O2 is byproduct

20
Q

PSII

A

electron transport chain that releases energy in form of a proton. Proton enters thylakoid space, joining protons split of H2O, resulting in proton gradient that drives ATP synthase

21
Q

PSI

A

harvests light, different absorption spectrum.

22
Q

NADPH

A

electron carrier for biosynthetic reactions

23
Q

Purpose of having 2 PS

A

one creates pool of protons to drive ATP formation

one creates pool of energy rich NADPH

24
Q

Cyclic photophosphorylation

A

ATP production uncoupled from NADPH (more ATP can be produced than NADPH)
e recycling
PSII passes e to PSI, gets excited and passes e to ferredoxin which passes e back to cyb6/f, releasing proton, forming only ATP

25
Q

Photophosphorylation

A

creation of ATP using proton gradient that is light dependent