Light Reactions

Question 1

what are chloroplasts for?

Answer 1

genes encode for proteins in photosynthesis

Question 2

how does chloroplast rise from?

Answer 2

pre-existing chloroplasts thru fission

Question 3

how many membranes does chloroplasts have?

Answer 3

3

Question 4

what are the 3 membranes of chloroplasts?

Answer 4

1. outer membrane
2. inner membrane
3. thylakoid membrane

Question 5

What are the features of outer membrane?

Answer 5

• relatively permeable
• contain porins

Question 6

What are the features of inner membrane?

Answer 6

• highly permeable
• require transporters

Question 7

What are the features of thylakoid membrane?

Answer 7

• site of light reactions
• contain intergral proteins
• contain pigments

Question 8

what are the two different functional units of plant chloroplasts in light energy conversion into chemical energy?

Answer 8

photosystems I (P700)
photosystems II (P680)

Question 9

Where are the photosystems located?

Answer 9

thylakoid membrane

Question 10

what are the feature of photosystem II?

Answer 10

absorbs @ shorter and more energetic wavelength

Question 11

What are is the order of photosystem

Answer 11

start with photosystem II then photosystem I

Question 12

What is the structure of photosynthetic apparatus , what are the four protein complexes?

Answer 12

1. Photosystem II
2. Cytochrome b6f complex
3. photosystem I
4. ATP synthase

Question 13

What do the four protein complexes have?

Answer 13

vectorial arrangement

Question 14

What are the two mobile carriers?

Answer 14

1. plastoquinone
2. plastocyanin

Question 15

what are stroma lamellae?

Answer 15

unstacked

Question 16

What are grana lamellae?

Answer 16

stacked

Question 17

What are the structure of PSII photosystem?

Answer 17

stacked regions

Question 18

What are the PSI photosystem/ETC Proteins/ ATP Synthase structure?

Answer 18

unstacked regions

Question 19

What are cyt b6f structure?

Answer 19

even distributed

Question 20

Where are is the ATP synthase?

Answer 20

unstacked stroma lamellae

Question 21

what is the process of production of ATP?

Answer 21

ATP produced needs to be released into stroma to be available for calvin cycle rxns

Question 22

what are antenna complexes?

Answer 22

light-harvesting complexes or LHC

Question 23

What does antenna complexes contain?

Answer 23

chlorophyll a, chlorophyll b and carotenoids

Question 24

What are the mechanism involved in antenna complexes?

Answer 24

resonance energy transfer (vibrational)

Question 25

how are energy passes of antennae complexes?

Answer 25

down energy gradient, higher energy (shorter wavelength) to lower energy (longer wavelength) thru resonance up to Reaction Center

Question 26

What happens when reached energy Reaction Center?

Answer 26

chlorophyll molecule of either PSII or PSI Chl molecule absorbs light energy and becomes excited Chl*

Question 27

what are the pigments associated with light-harvesting antenna complextes?

Answer 27

LHC II LHC I

Question 28

what happens when pigments are near the reaction centre?

Answer 28

longer wavelength maxima red shift in absorption max

Question 29

what does it give to reaction centre?

Answer 29

directionality/irreversibility to energy transfer

Question 30

how does light excited reaction centre chlorophyll molecule?

Answer 30

1. directly 2. thru resonance ( energy transfer from antenna molecules)

Question 31

what is the strongest oxidizing agent or oxidant (e- acceptor) in biological system?

Answer 31

excited PSII reaction centre chlorophyll (P680+)

Question 32

how is light energy converted to chemical energy?

Answer 32

thru the light-dependent reactions

Question 33

what are the types of ractions?

Answer 33

1. Non-cyclic Electron Flow 2. Cyclic Electron Flow

Question 34

What does the non-cyclic electron flow use?

Answer 34

PSII and PSI

Question 35

What is the non-cyclic electron flow?

Answer 35

thru linear electron flow pathway or the Z-scheme of photosynthesis

Question 36

What does the cyclic electron flow use?

Answer 36

PSI

Question 37

What is the cyclic electron flow?

Answer 37

thru non-linear electron flow pathway

Question 38

what does the PSII absorbs in the non-cyclic electron flow?

Answer 38

red light

Question 39

What does the PSI absorbs in the non-cyclic electron flow?

Answer 39

in far-red light

Question 40

what happens in the non-cyclic electron flow?

Answer 40

excited electron transferred to primary electron acceptor, convert from light to chemical energy

Question 41

what does the light absorption and electron transport generate?

Answer 41

ATP and NADPH thru Z-scheme

Question 42

what is the sequenece?

Answer 42

1. photon absorption in PSII (P680) or PSI (P700) 2. oxidation of water to generate electrons 3. electron transfer to cytochrome b6f or from cytochrome b6f 4. Electron transport to ferredoxin or to NADPH reductase 5. photophosphorylation

Question 43

what happens in the photon absorption in PSII and PSI reaction center

Answer 43

Absorb light lead to 1. splitting H2O 2. generating H+ gradient proteins D1 and D2 bind P680 reaction center chlorophyll and ETC

Question 44

What is PSII have?

Answer 44

20 polypeptides within thylakoid membrane

Question 45

What happens when excited electron from P680 do?

Answer 45

accepted by pheophytin

Question 46

what is the most stable in water moelcule?

Answer 46

splitting water - endergonic reaction

Question 47

what happens when P680* loses it's excited electron to Pheophytin?

Answer 47

oxidized to P680+

Question 48

what is the most powerful oxidizing agent?

Answer 48

P680+

Question 49

what can P680+ do?

Answer 49

photolysis of water - pulling electrons from H2O molecule

Question 50

what are features of plastoquinone?

Answer 50

hydrophobic mobile within membrane

Question 51

what are the features of plastocyanin?

Answer 51

small, water-soluble on lumen side

Question 52

how does