Topic 8: Photosynthesis

Front 1

Define photosynthesis

Back 1

a process that converts light energy into chemical energy (sugars)

Front 2

Photosynthesis occurs in ...

Back 2

free-living bacterial cells or in chloroplasts

Front 3

Light reactions

1. requires

2. converts

3. produces

4. happens where

Back 3

1. light dependent

2. convert solar energy to chemical energy

3. produces O2, ATP and NADPH

4. thylakoid membrane

Front 4

Calvin cycle (carbon fixation)

1. light dependent?

2. is a process of

3. uses what kind of energy

4. happens where

Back 4

1. not light dependent, does not require light

2. process of carbohydrate synthesis

3. uses chemical energy from light rxtns

4. stroma

Front 5

Chloroplast role in light dependent rxtns

Back 5

pigments in chloroplast used to absorb light energy

Front 6

Main photosynthetic pigments are

Back 6

chlorophyll a and b

Front 7

1. Chlorophyll a absorbs and reflects

2. Chlorophyll a absorbs and reflects

Back 7

1. absorbs: red/blue reflects: dark green

2. absorbs: red/blue reflects: light green

Front 8

1. Accessory pigments job

2. 2 accessory pigments are

Back 8

1. absorb energy and transfer it to chlorophyll a

2. carotenoids and anthocyanins

Front 9

1. carotenoids absorb, reflect

2. anthocyanins absorb, reflect

Back 9

1. absorb: red/green reflect: yellow, orange, red

2. absorb: green, yellow reflect: purple, blue, red

Front 10

Chlorophyll structure and function

Back 10

1. porphyrin ring absorbs light

2. hydrocarbon tails anchors pigment in thylakoid membrane

Front 11

light harvesting unit located in

2. contains

Back 11

thylakoid membrane

2. several light harvesting complexes: many chlorophyll molecules attached to proteins, gather light energy and transfer it

Front 12

3 ways electrons can release or transfer energy

Back 12

1. fluorescence

2. resonance transfer

3. electron transfer

Front 13

What happens in the light harvesting complexes? (2)

Back 13

1. pigment molecule absorbs photon

2. energy transferred from pigment molecule to pigment molecule by resonance transfer

Front 14

What happens in the reaction-center complex in the middle?

Back 14

(mostly made of protein)

1. pair of special chloro. a molecules accept energy from light-harvesting complexes

2. primary e- acceptor accepts excited e- from the chlorophyll a pair

Front 15

Photosystem 2 (PSII)

1. acts first or second

2. absorbs light best at

3. chlrorphyll a pair called

Back 15

1. first

2. 680nm

3. P680

Front 16

Photosystem 1 (PSI)

1. acts first or second

2. absorbs light best at

3. chlorophyll a pair called

Back 16

1. second

2. 700nm

3. P700

Front 17

Linear Electron Flow (8)

Back 17

1. P680 transfers its high energy electron to the primary electron acceptor

2. P680 chlorophyll now has an electron hole that must be filled by an electron donor (water)

3. excited electrons move from primary e acceptor of PS2 thru an ETC

4. movement of e- down the ETC releases energy at each step (exergonic)

5. chlorophyll a molecules in light harvesting complexes of PS1 absorbs photons of light

6. transer their energy to P700 chlorophyll pair of PS1

7. low energy e- released from bottom of ETC (Pc) fills e- hole in P700

8. NADP+ reductase transfers 2 e- from ferredoxin to NADP+

(reduces NADP+ to NADPH in stroma)

Front 18

What happens in chemiosmosis (3)

Back 18

1. conc. gradient of protons built up across thylakoid membrane

2. protons diffuse out of the thylakoid into the stroma through ATP synthase (released enrgy causes ATP synthase to rotate)

3. ATP is made in stroma from ADP + Pi (phosphoylation - enrgy originally came frm light)

Front 19

H+ concentration

1. thylakoid space

2. stroma

Back 19

1. high

2. low

Front 20

H+ released into stroma from chemiosmosis can be (2)

Back 20

1. added to NADP+ to make NADPH

2. actively transported back into thylakoid space

Front 21

Cyclic electron flow, what happens (4

Back 21

1. e- in P700 excited and transferred to PSI primary acceptor

2. high energy e- move to Fd

3. e- move backwards to cytochrome complex (protons pumped and ATP is produced by chemiosmosis)

4. e- move to Pc then back to P700 to fill hole

Front 22

Why is cyclic e- flow used?

Back 22

1. linear e- flow creates equal amounts of ATP and NADPH but since calvin cycle uses more ATP than NADPH that creates an imbalance, cyclic flow allows cell to make extra ATP w/o making more NADPH to balance levels

Front 23

Light-independent reactions synthesize

Back 23

sugars using energy from light dependent reactions (ATP and NAPH)

Front 24

The Calvin Cycle is a(n) ___________ and ______________ process, the products (____) have (more/less) energy than the reactants (___)

Back 24

anabolic and endergonic

(sugar) more (CO2)

Front 25

Where does the Calvin Cycle receive its energy?

Back 25

ATP and NADPH from light reactions

Front 26

The carbohydrate produced from the Calvin Cycle is is

Back 26

gylerceraldehyde-3-phosphate (G3P)

- 3 carbon sugar

- high energy

Front 27

To make 1 G3P you need

Back 27

3 molecules of CO2 to be fixed (3 turns of the cycle)

Front 28

What is the overall formula for 3 turns of calvin cycle?

Back 28

3 CO2 + 9 ATP + 6 NADPH --> 1G3P

Front 29

What is RUBISCO?

Back 29

an enzyme that fixes CO2

(5C sugar)

Front 30

Phases of Calvin Cycle (3)

Back 30

1. Carbon fixation

2. Reduction

3. Regeneration

Front 31

Role of ATP in reduction

Back 31

phosphates added to reactants provide energy to drive reactions

Front 32

Role of NADPH in reduction phase

Back 32

each molecule donates 2 high energy electrons for reduction of reactants

Front 33

Reduction produces

Back 33

6 high-energy G3P

(1 G3P is released for use (new gain = 3c)

(5 G3P is used to regenerate RuBP (15 C resused))

Front 34

What happens in regeneration?

Back 34

5 G3P + 3 ATP ---> 3 RuBP

- RuBP are used in next cycle to fix 3 more CO2

Front 35

G3P can be used to make (3)

Back 35

1. sugars (glucose) for cellular resp, or building blocks for other mol.

2. energy storage compounds (starch)

3. cell wall constituents (cellulose)