Catalyst Could humans survive without plants? Why, if

at all, are plants important?

Cell Parts: Chloroplast Photosynthesis: occurs only in plants (not

animals!)

6CO2 + 6H2O + light C6H12O6 + 6O2

(glucose sugar) (oxygen)(carbon dioxide) (water) (energy)

stored in plant; for plant use or animal

use with cellular respiration

released from

leaves

absorb through leaves

from roots from sun

Image Source: http://upload.wikimedia.org/wikipedia/commons/1/11/Chloroplast-new.jpg

Chloroplast: capture light energy; make food energy

Cell Parts: Chloroplast

Image Source: http://upload.wikimedia.org/wikipedia/commons/1/11/Chloroplast-new.jpg

Thylakoid: flattened discs containing chlorophyll Granum (pl. Grana): stack of thylakoids Stroma: fluid inside chloroplast (similar to a cell’s cytoplasm) Lamella: links thylakoids in grana together Lumen: inside of the thylakoid

Cell Parts: Chloroplast Chlorophyll: pigment in chloroplasts that

absorbs light Review: Visible Light Spectrum

VioletIndigoBlueGreen OrangeRedYellow

“VIB G YOR” (or “ROY G BIV”)

Cell Parts: Chloroplast The color you see is the color that is

reflected

Chlorophyll reflects green; absorbs ROYBIV!

RO

YG

BI

V

Reflects:

Absorbs:

We See:

RED

OTHER COLORS

RED

Light energy the plant uses!!!!

Cell Parts: Chloroplast Phase I: Light-Dependent Reactions Phase 2: Light-Independent Reactions / Calvin

Cycle

Image Source: bioweb.uwlax.edu

Cell Parts: Chloroplast Phase 1: Light-Dependent Reactions

Occurs at thylakoid membrane (Lumen Stroma) Requires light (dependent)

Cell Parts: Chloroplast Phase I: Light-Dependent Reactions

LUMEN

STROMA

H+

H+

H+

H+

H2O

½O2

2H+

ADPATP

ATP Synthase(enzyme/protein)

P

Thylakoid Membran

e

Light Light

e-

e-

e-

Photosystem II

Photosystem I

Ferrodoxin

H+

H+

4H+

NADP+

NADPH

H+

Another e- carrier (like NAD+, FAD)

Cell Parts: Chloroplast Phase 1: Light-Dependent Reactions

Mini-Steps:

1. Photosystem II absorbs light energy

to spilt water into: oxygen, H+s in

lumen, & activated e- that enters the

ETC.

2. Electron Transport Chain – e-s move

through membrane to pump H+s into

lumen.

3. Photosystem I absorbs light energy

and re-energizes e-, which moves to

ferrodoxin (protein) to form NADPH.

4. H+s accumulate in lumen to create a

gradient (high [H+] in lumen, low

[H+] in stroma).

5. ATP Synthesis – As H+s move across

thylakoid membrane through ATP

Synthase, ADP is converted into ATP.

LUMEN

STROMA

H+

H+

H+

H+

H2

O

½O2

2H+

ADP

ATP

ATP Synthase(enzyme/protein)

P

Thylakoid

Membrane

Light Light

e-

e-

e-

Photosystem II

Photosystem I

Ferrodoxin

H+

H+

4H+

NADP+

NADPH

H+

Another e- carrier (like NAD+, FAD)

Chemiosmosis

Cell Parts: Chloroplast Phase 2: Calvin Cycle / Light-Independent

Reactions In stroma Doesn’t directly require light energy (independent) ATP & NADPH = energy, but not stable converted to

glucose sugar.

Cell Parts: Chloroplast Phase 2: Calvin Cycle

12 3-PGA

C C C

12 G3P

C C C

Rubisco

CO26

ribulose 5-phosphate

C C C C C

ribulose 1,5-bisphosphate6

C C C C C

2 G3P

C C C

Transported from chloroplast to make glucose, fructose,

starch, etc.(carbohydrates /

sugars)

12 ATP

12 ADP

12 NADPH

12 NADP+

6 ATP

6

6 ADP

Calvin Cycle

(3-phosphoglyceri

c acid)

(glyceraldehyde 3-

phosphate)

Cell Parts: Chloroplast Phase 2: Calvin Cycle

Mini-Steps:

1. Carbon Fixation: Carbon dioxide

joins a five-carbon molecule to

make twice as many three-carbon

molecules.

2. ATP & NADPH turn 3-PGA into G3P

(a high energy molecule). ATP

supplies phosphate groups;

NADPH supplies H+s and e-s.

3. Two G3P molecules leave to make

glucose & other carbohydrates.

4. Rubisco (enzyme/protein) converts

remaining ten G3P molecules into

five-carbon molecules to be used

in carbon fixation.

12 3-PGA

C C C

12 G3P

C C C

Rubisco

CO26

ribulose 5-phosphate

C C C C C

ribulose 1,5-bisphosphate6

C C C C C

2 G3P

C C C

12 ATP

12 ADP

12 NADPH

12 NADP+

6 ATP

6

6 ADP

Calvin Cycle

(3-phosphoglyceric acid)

(glyceraldehyde 3-phosphate)

Cell Parts: Chloroplast Phase I: Light-Dependent Reactions

Photosystem II uses light to split water: H+s, oxygen, & e-.

ETC: e- pumps H+s into lumen. Photosystem I re-energizes e- with light: forms NADPH. H+s in lumen create a concentration gradient. H+s move across thylakoid membrane through ATP

Synthase: converts ADP into ATP

Phase 2: Light-Independent

Reactions / Calvin Cycle

CO2 molecules join with 5-carbon

molecules to make 3-PGA

molecules.

NADPH and ATP from Light-

Dependent Reactions turn 3-PGA

into G3P.

Two G3P molecules leave the Calvin

Cycle to form glucose & other

carbohydrates.

Remaining G3P molecules

converted by Rubisco into 5-carbon

molecules that restart the cycle.

Image Source: bioweb.uwlax.edu