Lecture 19 & 20 : photosynthesis

Question 1

what is photosynth

Answer 1

A process that converts light energy into chemical energy. This chemical energy is used to convert atmospheric CO2 into carbohydrates

Question 2

what is used instead of NADH in photosynth

Answer 2

NADPH

Question 3

photosynth equation net

Answer 3

6CO2 + 6H2O + energy –>C6H12O6 + 6O2

Question 4

what gets oxidised to produce the e- that go throught the e- chain

Answer 4

water (oxidised to O2)
this is the light dependent phase btw

Question 5

what is the dark phase reaction

Answer 5

CO2 reduced to carbohydrate
can happen without light

Question 6

whta does CO2 need to get reduced

Answer 6

ATP and NADPH

Question 7

how is NADPH made

Answer 7

electrons from the H2O oxidation reduce NADP+ to NADPH

Question 8

where in the chloroplast does phtosynth occur

Answer 8

thylakoid (membrane specifically cuz thats where all the machinery is)

Question 9

what is ubiquinone equivalent in plants

Answer 9

plastoquinone

Question 10

what type of cytochrome big membrane thing connects PSI and II in plants

Answer 10

cytochrome bf
links PSI and PSII

Question 11

what is between cytochrome bf and PSI (equivalent to cytochrome c molecule)

Answer 11

plastocyanin

Question 12

what passes e- to NADP reductase

Answer 12

ferrodoxin

Question 13

where do e- move from and into through ATP synthase

Answer 13

thylakoid lumen to chloroplast stroma

Question 14

what are the 2 pigments in phosotsystems

Answer 14

chlorophylls
carotenoids

Question 15

what is final e- acceptor

Answer 15

NADP+

Question 16

what wavelengths does PSI respond to

Answer 16

less than 690nm

Question 17

name of pgments that first capture the light

Answer 17

antenna pigments

Question 18

what does the ‘special pair’ of chlorophyll molecules do in PSII

Answer 18

act as an energy trap
and e- can leave from here

Question 19

what ion in chlrophylls

Answer 19

Mg2+

Question 20

what is the one diff between chlorophyll a and b

Answer 20

a methyl group is an alcohol group

Question 21

what type of structure do chlorophyll have that makes it so e- can more readily absorb light energy

Answer 21

planar structure

Question 22

what nm is light not absorbed and gets reflected (hence green colour)

Answer 22

500-600nm

Question 23

when special pair loses its e- where does it replace it with

Answer 23

e- from H2O

Question 24

name of special pair in PSII

Answer 24

P680
P680* when it captures e-

Question 25

what is oxygen evolving centre

Answer 25

near the chlorophyll in PSII e- from H2o captured here to go to oxidised P680

Question 26

what does oxygen evolving contain

Answer 26

1 Ca2+ and 4 Mn ions which have h2o bound to it and when e- snatched from this given to chlorophyll

Question 27

what is in between oxygen evolving centre and chlorophyll

Answer 27

tyrosine mediates e- trnasfer

Question 28

how many photons needed to generate one moleucle of o2

Answer 28

4 therefore 4e-

Question 29

how many protons transferred in total in the process of e- transfer to plastiquinone

Answer 29

4 from water released in thylakoid lumen 4 from stroma transferred to PQ to make PQH2

Question 30

how many protons does cyt bf transfer to thylakoid lumen and how

Answer 30

2 via Q cycle

Question 31

properties of plastocyanin

Answer 31

blue copper protein - this is what gets reduced, 1 at a time soluble - exists in thyl memb

Question 32

Where does p700* recover its e- from

Answer 32

Plastocyanin

Question 33

what is in between psI and ferrodoxin

Answer 33

Iron sulphur clusters Act as ijtermediate

Question 34

Where is ferrodoxin located

Answer 34

in stromal side

Question 35

What structure in NADP+ reductase allows the reduction of NADP+

Answer 35

FAD Which can capture the e- and h+ one at a time and then pass the e- to nadp+ (2at a time)

Question 36

In what form are p680 and p700 good right reducing agents

Answer 36

when they are excited

Question 37

In what form are p680 and 700 good oxd agents

Answer 37

when they lose the e- and become +ve

Question 38

What are the subunits of atp synthase in atp synthase

Answer 38

CF0 and CF1 Same stalk and knob structure as in humans

Question 39

How many photons to make 3 atp

Answer 39

8 So 2.7 per atp

Question 40

What happens if no co2 or nadp+ is available

Answer 40

E- go from ferrodoxin back to cytochrome bf complex Atp still synthesised, but no o2 or nadph made