Photosynthesis Chapter 10 Part 1 Unit 3 Energy

Photosynthesis Chapter 10 Part 1 Unit 3

Energy Needs of Life ◦ Autotrophic Make own food Photoautotrophs, Chemoautotrophs ◦ Heterotrophic Unable to make own food Consumers, Decomposers

Sites of Photosynthesis mesophyll: chloroplasts are located stomata: pores in leaf (CO 2 enter/O 2 exits) chlorophyll: green pigment in thylakoid

Chloroplast Structure Double Membrane Stroma Fluid-filled interior Thylakoid Sacs Chlorophyll Grana Stacks of thylakoids Thylakoid space

Photosynthesis Endergonic process sunlight as energy source Directly or indirectly supplies energy 6 CO 2 + 6 H 2 O + light energy C 6 H 12 O 6 + 6 O 2

Photosynthesis = Light Reactions + Calvin Cycle

Photosynthetic pigments Pigments absorb different λ of light Chlorophyll: absorb violet-blue/red light, reflect green Ø chlorophyll a (blue-green): light reaction, converts solar to chemical E Ø chlorophyll b (yellow-green): conveys E to chlorophyll a Ø carotenoids (yellow, orange): photoprotection, broaden color spectrum for photosynthesis

Photosystems of photosynthesis ◦ collections of chlorophyll molecules ◦ act as light-gathering molecules ◦ Photosystem II chlorophyll a P 680 = absorbs 680 nm reaction wavelength red light ◦ Photosystem I center chlorophyll b P 700 = absorbs 700 nm wavelength red light antenna pigments

chlorophyll a ETC of Photosynthesis Photosystem II chlorophyll b Photosystem I

Light Reaction (Linear electron flow) Chlorophyll excited by light 2. Energy passed to reaction center of Photosystem II 3. electrons captured by primary electron acceptor 4. Water is split to replace electrons O 2 formed 1.

5. 6. 7. 8. 9. Electrons passed to Photosystem I via ETC Energy transfer pumps H+ to thylakoid space ATP produced by photophosphorylation electrons move from PS I’s primary electron acceptor to 2 nd ETC NADP+ reduced to NADPH MAIN IDEA: Use solar E to generate ATP & NADPH to provide E for Calvin cycle

Cyclic Electron Flow Uses PS I only; produces ATP for Calvin Cycle (no O 2 or NADPH produced) Certain bacteria

Both respiration and photosynthesis use chemiosmosis to generate ATP