Photosynthesis

I.Photosynthesis A.Process that traps light energy & uses it for carbohydrate synthesis or creation. B.Phototrophs - both plants and bacteria

C. 2 major processes 1. light rxns (light-dep. rxns): protons from H 2 O make ATP from ADP and P i & electrons from H 2 O reduce NADP + to NADPH. a. H 2 O is split H goes to dark rxn

b. ATP: adenosine triphosphate c. ADP: adenosine diphosphate d. NADP + : nicotinamide adenine dinucleotide phosphate e. NADPH: reduced nicotinamide adenine dinucleotide phosphate

2. Dark rxns (light-independent rxns): uses NADPH & ATP in carbon update. a. meaning: C from CO 2 & H comes from light rxn - CHO which makes glucose

3. Both can occur during daylight 4. Overall chemical equation: 6H 2 O + 6CO 2 C 6 H 12 O 6 + 6O 2 light

II. Chloroplast

A. Thylakoid Membrane 1. highly folded membrane network a. CO 2 diffuses easily across membrane

2. Site of light dependent rxn that produce NADPH & ATP

B. Stroma 1. Aqueous matrix 2. enzymes breaks down CO 2. Keep C to make CHO 3. site of dark rxn

C. Lumen 1. aqueous space within thylakoid membrane 2. ATP synthesis

D. Grana 1. thylakoid membrane folded into flattened vesicles & stacked

Parts of the chloroplasts Grana- stacks of Thy. Membrane Stroma (fluid) Thylakoid Membrane: sac that contains chlorophyll Lumen (fluid)

E. Chlorophyll – a & b: green 1. Chl a & Chl b 2. absorbs light in violet/blue to orange/red region 3. Reflects green

F. Accessory pigments 1. carotenoids: oranges 2. phycobilins a. phycoerythrin: red b. phycocyanin: blue 3. Xanthophyll: Yellows

III.Light –Dependent Rxns A. Sunlight excites chlorophyll via antenna complexes B. Passes energy to electron C. Electron pass down Electron Transport Chain (ETC) – twice

1.As electrons “fall” they lose energy a. Energy trapped in ATP D. Electron passed to carrier molecule – NADP + E. Combine with H ion from H 2 0 – NADPH

1. Photosystem II a. located in grana & unstacked region b. splits molecules of H 2 O into 1/2 O 2, 2H, and 2 electrons – photolysis

c. ATP made from ADP + P i

2. Photosystem I a. unstacked region of T.M. - lumen b. electron falls down ETC & combines with 2H + from the surrounding medium and NADP + to produce NADPH + H +.

3. Z – scheme: PII & PIZ – scheme

IV. Light independent rnxs A. Use C from CO 2 to make glucose B. Takes place in the Stroma C. Also known as Calvin Cycle 1. Melvin Calvin

2. 6 rounds to get 1 glucose a. CO 2 ≠ C 6 H 12 O 6 animation

Let’s Review: Light-dependent reaction also known as light reaction. - Take place in T.M. - Light energy breaks apart H 2 O. H kept & combines with NADP + to form NADPH for dark reaction and O given off.

- Electrons fall down ETC and release energy – this energy is trapped in ATP

Next is Light-Independent Reactions also known as the Dark Reaction or Calvin Cycle. -Take place in the stroma -Uses ATP & NADPH made in light rxn

-Uses energy from ATP when broken down to ADP & P -takes H from NADPH to combine with CO 2 to form CHO: glucose C 6 H 12 O 6