Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCB 3010 > FINAL EXAM: photosynthesis > Flashcards

FINAL EXAM: photosynthesis Flashcards

1
Q

photosynthesis 2 parts

A

light reactions: photophosphorylation (take place in the light, makes ATP, NADPH)

carbon assimilation reactions/carbon fixation: dark reactions; (anytime but mostly in the light; use ATP, NADPH, H2O, CO2; makes triose phosphates)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

photophosphorylation

A

light excites an electron which is transferred to another molecule

transfer is Redox — causes charge separation

energy from redox reactions in electron transport is used to transfer H+ across membrane to drive synthesis of ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

source of electrons in photophosphorylation

A

water

passed via chain of proteins to ultimate electron acceptor, NADP+

oxygen is byproduct of water oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

chemiosmotic theory

A

ADP + Pi —> ATP is unfavorable

synth. of ATP in chloroplast is similar to oxpho in mito.

energy released by electron transport is used to move H+ across membrane for electrochemical grdient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

maintains proton gradient

A

chloroplast thylakoid membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

third membrane in chloroplasts

A

folds to make thylakoids

H+ gradient formed across thylakoid with high H+ in lumen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

photopigments absorb different wavelengths of light

A

energy is transferred to the photosynthetic reaction center

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

process of producing charge separation from light energy

A

light excites an antenna molecule (chlorophyll or accessory pigment); raises an electron to higher energy level

excited antenna molecule passes energy to neighboring chlorophyll molecule (exciton transfer), exciting it

energy is transferred to a reaction-center chlorophyll, exciting it

excited reaction-center chlorophyll passes an electron to an electron acceptor

electron hole in reaction center is filled by electron from electron donor

absorption of a photon has caused separationof charge in the reaction center

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

chloroplasts coupling of 2 photosystems

A

produce O2, NADPH, and proton gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

photosystem II

A

light hits photosystem II

energy is transferred to the Reaction Center

electron in RC chlorophyll is excited - transferred to pheophytin

2 water molecules from lumen are oxidized

  • 4 electrons held then passed to reaction center one at a time to replace excited electrons
  • H+ are on lumen of membrane, builds gradient

electron in pheophytin passed to plastoquinone A and then to plastoquinone B

plastoquinone B collects 2e- and then 2H+ from stromal side to become fully reduced plastoquinol B (builds gradient)
- 2 H+ of light must excite 2e- to produce 1 fully reduced plastoquinone B (PQb to PQbH2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

cytochrome b6f complex

A

similar complex II of ETC

uses Q cycle to transfer electrons

oxidizes 2 small hydrophobic quinones (plastoquinol B to plastoquinone B)
transfers e- from each plastoquinol to:
- small hydrophilic protein (plastocyanin; carries 1e- on Cu)
- oxidized plastoquinone to make plastoquinol

protons from plastoquinol oxidation end up in thylakoid lumen (builds gradient)

protons to reduce plastoquinone come from stroma (builds gradient)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

plastocyanin

A

can move through the lumen to deliver electrons to photosystem 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

cytochrome b6f complex links

A

PS II and PS I and translocations protons into the lumen

Q cycle is not taking place in the membrane; it takes place in the protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

photosystem I

A

light hits photosystem I

  • excites an electron in the reaction center which is passed on to an acceptor chlorophyll
  • electron replaced by oxidation of plastocyanin (each plastocyanin can transfer 1 e-)

electron passes from acceptor chlorophyll to phylloquinone to 3 FeS centers to Ferredoxin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

ferredoxin

A

an FeS containing protein on the stromal side of the membrane

mobile hydrophilic protein
carries 1 e-

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ferredoxin: NADP oxidoreductase

A

soluble enzyme in the stroma

ferredoxin binds to Ferredoxin: NADP oxidoreductase

2 ferredoxin are oxidized (1 e- carrier) to reduce FAD+ to FADH2 (can collect 2 e-; one at a time)

FADH2 is reoxidized and NADP+ is reduced to NADPH - the final electron acceptor

Protons to reduce NADP+ coming from stromal side of membrane increasing strength of proton gradient

17
Q

photosystem II reaction

A

2e- (p680) + 2H+(s) + PQb + 2photons

PQBH2

e- replaced from oxidizing 2H2O (4e- generated) and O2 made (4H+ to lumen)

18
Q

cytochrome B6F complex reaction

A

PQbH2 + 2pcyan2+ + 2H+(s)

PQb + 2pcyan+ + 4H+(l)

19
Q

photosystem 1 reaction

A

e-(p700) + Fd3+ + photon

Fd2+

electron replaced from oxidizing a plastocyanin

20
Q

Fd

A

ferrodoxin

21
Q

PQ

A

plastoquinone

22
Q

pcyan

A

plastocyanin

23
Q

ferredoxin: NADP+ oxidoreductase reaction

A

2Fd2+ + NADP+ + H+

2Fd3+ + NADPH

24
Q

ATP synthesis

A

electron transport produces proton gradient across the thylakoid membrane — high H+ in lumen

ATP synthase allows protons back to stromal side of the membrane - uses energy to synthesize ATP

25
Q

how is the proton gradient produced?

A

protons generated from oxidation of water in lumen

removal of protons from stroma to make PQH2 in photosystem II

Q cycle of cytochrome b6f complex moves protons to the lumen and removes protons from stromal side

proton for reduction of NADPH in ferredoxin: NADP oxidoreductase come from stroma

26
Q

production of ATP

A

utilizing the 4e- from forming 1 O2

8 photons of light are absorbed between both photosystems

12 protons moved to the lumen

return of protons to the stroma generates 3 ATP

27
Q

overall photophosphorylation reaction

A

2H2O + 8 photons + 2NADP+ + ~3ADP + ~3Pi

O2 + 2NADPH + ~3ATP

28
Q

photophosphorylation is in some ways the opposite of oxidative phosphorylation

A

PP: H2O is oxidized to O2 and NADPH is produced

Oxpho: NADH and FADH2 are oxidized, H2O is produced from reduction of O2

protons are moved into the lumen of the thylakoid but out of the matrix of the mitochondria

oxpho: energy comes from reduced molecules being oxidized to make ATP
PP: energy comes from light and reduced molecules (NADPH) are generated (as well as ATP)

29
Q

cyclic photophosphorylation

A

when NADP+ is depleted (lots of light; PP continuous), electrons can be cycled

H+ are transferred to the lumen during Q cycle so more ATP can be made — energy from light can be utilized

no NADPH (because there is enough) and no O2 are made (at PSII)

30
Q

cycling of electrons when NADP+ is depleted

A

ferredoxin transfers electrons to plastoquinone B (final acceptor in PSI)

at the CB6f complex: electrons transferred to plastocyanin

PS1 runs using e- from plastocyanin to make ferredoxin again

MCB 3010 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions