Chpt 19

Question 1

Structure of Chloroplast

Answer 1

3 membrane layers:

• Outer
• Inner
• Thylakoid-thylakoid membrane organized into stacked (appressed) and unstacked regions (Nonapressed). Stacked regions are called grand

3 compartments:

• Intermembrane space
• Stroma
• Thylakoid lumen

Question 2

Chloroplast Function

Answer 2

1) Photosynthesis-reduces Carbon dioxide to carbohydrates
2) Synthesizes
- amino acids
- fatty acids
- lipids
3) Reduce nitrate (NO2-) to ammonia (NH3)
4) Storage of pigments, starch, and lipids

Question 3

What do plastids develop from?

Answer 3

Proplastids- small undifferentiated organelle present in early plant development

Question 4

Plastid Development

Answer 4

Proplastids->Etioplasts-> Plastids

Question 5

Plastids are classified by:

Answer 5

• Presence/absence of thylakoid membrane
• type of pigment
• type of material stored

Question 6

Types of plastids?

Answer 6

1) Chloroplasts
2) Chromoplasts
3) Leucoplasts

Question 7

Chlorplasts

• Presence/absence of thylakoid membrane
• type of pigment
• type of material stored

Answer 7

TYPE OF Plastid

• thylakoid membranes
• pigment-chlorophyll
• carry out photosynthesis-don’t store anything

Question 8

Chromoplasts

• Presence/absence of thylakoid membrane
• type of pigment
• type of material stored

Answer 8

Type of Plastid

• lack thylakoid membrane
• pigment=carotenoids-pigment of flowers
• functions (other than color) unknown

Question 9

Leucoplasts

Answer 9

Type of plastid

• lack thylakoid membrane
• no pigments present
• storage of energy molecules

2 Types:

1) Amyloplasts
- starch storage
2) Elaioplasts
- lipid storage

Question 10

Photosynthesis

Answer 10

6CO2 + 6H2O ->C6H12O6 + 6O2

1) Light reaction in thylakoid membrane that synthesizes ATP and NADPH
- Photosystem II (PSII)-P680
- Photosystem I (PSI)-P700

Noncyclic flow of electrons (PSII and PSI)-synthesis of ATP and NADPH

Cyclic flow of electrons (PSI only)-synthesis of ATP only

2) Dark Reaction (Calvin cycle) in Stroma
- reduces carbon dioxide to carbohydrates

Question 11

Complexes of Light Reactions

Answer 11

Photosystem II (PSII)

• PO (plastoquinone)
• cyt bf (cytochrome bf)
• PC (plastocyanine)

Photosystem I (PSI)

• Fd (ferredoxin)
• Fd-NADP+ reductase
• ATP synthase

Question 12

Photosystem II function

Answer 12

1) splits water to hydrogen and oxygen
- 4H+ released into thylakoid lumen
- 1 O2 released into thylakoid lumen
- 4 e- used to reduce 2Q to 2QH2
2) energizes electrons using solar energy (Photon)
3) establishes proton gradient which is used to synthesize ATP

Question 13

Platoquinone function

Answer 13

small lipid soluble protein that transfers electrons from PSII to cyt bf
-redox state cycles from plastoquinone (Q) to Plastoquinol (QH2-reduced) back to plastoquinone (Q)

Question 14

plastocyanine function

Answer 14

transfers electrons from cyt bf to PSI

Question 15

Photosystem I function

Answer 15

• electrons are reenergized by solar energy

- NADP+ reduced to NADPH

Question 16

Ferredoxin function

Answer 16

Transfers one electron from PSI to Fd-NADP+ reductase

Question 17

Fd-NADP+ reductase function

Answer 17

reduces NADP+ to NADPH

• FAD accepts 1e- and 1H+ from 2 Fd (2e- and 2H+ total)
• transfers hydride (H-) to NADP+ which picks up H+ from stromal side of thylakoid membrane to synthesize NADPH

Question 18

ATP synthase function

Answer 18

phosphorylates ADP To ATP using energy harnessed from the proton gradient

Question 19

NON cyclic flow of electrons

Answer 19

Water-> PSII-> Q-> cyt bf->PC-> PSI-> Fd-> Fd-NADP+ reductase-> NADH

produce NADPH in addition to ATP due to proton gradient
-both ATP and NADPH end up in stroma

Question 20

pH of stroma

Answer 20

8

Question 21

Cyclic Flow of electrons

Answer 21

PSI-> Fd-> Q-> cyt bf-> PC-> PSI

Produces ONLY ATP (NO NADPH)

Question 22

Chlorophyll a and b

-structure

Answer 22

substituted tetrapyrole (like heme)

• pyrrole-> N complexed to Mg2+
• conjugated polyene-alternating single/double bonds

Phytol-hydrophobic 20 Carbon tail

Chlorophyll a and b differ by one functional group

• A-Methyl
• B- formyl group

Question 23

Chlorophyll a and b

-function

Answer 23

captures photon of light in the reaction center

-chlorophyll a and b have different wave lengths of light

Question 24

Carotenoids

-structure

Answer 24

conjugated double bond system

Question 25

Carotenoids | -function

Answer 25

- absorb light between 400-500 nm - Provides yellow and red colors of fruit and flowers- chlorophylls a and b are destroyed allowing the carotenoids color to show

Question 26

Reaction center

Answer 26

pigments (chlorophyl a and b and carotenoids) in/on ct thylakoid membrane absorb photons of light and transfer energy to the reaction center containing a special pair of chlorophyl a molecules

Question 27

Organization of Photosynthetic complexes

Answer 27

- PSII located in stacked regions - PSI and ATP synthase located primarily in unstacked regions - Cyt bf located in both stacked and unstack regions - Plastoquinone (Q) and Plastocyanine (PC) transfer electrons from different regions

Question 28

Photosystem II structure

Answer 28

Transmembrane complex of thylakoid membrane | -Contains "special pair" P 680-contains two chlorophyll molecules bond between core subunits D2and D1

Question 29

Photosystem II electron flow

Answer 29

- 2 H2O - Mn2+ center - P680-> Chlorophyl A-special pair - Qa-bound - Qb-soluble

Question 30

Heart of Photosystem II is?

Answer 30

Manganese Center

Question 31

Mn2+ center Structure

Answer 31

contains 4 Manganese-that exist in 4 different oxidation states (2,3,4,5) - 1 calcium - Tyrosine called Z

Question 32

Mn2+ Center function

Answer 32

activates 2 H2O molecules - allowing oxidation (electron extraction) by the special pair (P680) forming 1 O2+ 4H+ + 4e- - the electrons are moved one at a time S1->S2->S3->S4->S5->S0

Question 33

How many photons of light is required to form one O2

Answer 33

4 photons

Question 34

cytochrome bf | -structure

Answer 34

``` Transmembrane complex of thylakoid membrane Four subunits -cytochrome with two b type hemes -Rieske center Fe-S protein -Cytochrome F with a c-type cytochrome ``` Homologous to complex III it uses THE Q CYCLE

Question 35

cytochrome bf | -function

Answer 35

uses energy harvested from electrons to transfer protons into thylakoid lumen

Question 36

Plastocyanin | -structure

Answer 36

small, soluble copper containing protein on the luminal side of the thylakoid membrane

Question 37

Photosystem I | -structure

Answer 37

Massive transmembrane complex of thylakoid membrane | -contains special pair P700 held between major subunits psaA and psaB

Question 38

Photosystem I electron flow

Answer 38

Pc-> P700-chlorophyll A special pair-> Ao-chlorophyll->A1-quinone-> 4Fe-4S-> Fd

Question 39

Ferredoxin Structure

Answer 39

- Soluble protein on stromal side of thylakoid membrane | - contains 2Fe-2S

Question 40

Ferredoxin-NADP+ structure

Answer 40

Transmembrane flavoprotein of thylakoid membrane | -Contains FAD as prosthetic group

Question 41

Light Harvesting Complex II (LHC-II) | structure

Answer 41

abundant ct membrane protein binds: - 7 chlorophyl a molecules - 6 chlorophyl b molecules - 2 carotenoid molecules

Question 42

Light harvesting complex II (LHC-II) | -function

Answer 42

funnels energy from photons of light to reaction center

Question 43

Calvin cycle (Dark Reaction)

Answer 43

Catalyzed by Rubisco (Ribulose bisphosphate carboxylase) and other enzymes - occurs in stroma - uses ATP and NADPH from light reaction - reduces carbon dioxide to carbohydrates