CHAPTER 8 — PHOTOSYNTHESIS

Photosynthesis

Process that converts solar energy into chemical energy

Photosynthesis equation

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

Chloroplast

Organelle where photosynthesis occurs

Thylakoid membrane

Membrane containing photosystems and electron transport components

Thylakoid space

Space where H+ concentration becomes high during light reactions

Stroma

Fluid-filled area where the Calvin cycle occurs

Granum

Stack of thylakoids

Light reactions

Reactions that use light to produce ATP and NADPH and release O2

Calvin cycle

Reactions that use ATP and NADPH to convert CO2 into sugar

Photosystem II

First photosystem in the light reactions

Photosystem I

Second photosystem in the light reactions

Electron transport chain

Series of electron carriers that transfer electrons and help create an H+ gradient

ATP

Energy-carrying molecule produced during the light reactions

NADPH

Electron carrier produced during the light reactions

ATP synthase

Protein that uses the H+ gradient to make ATP

H+ gradient

Difference in H+ concentration across the thylakoid membrane

Water splitting

Process that provides electrons and releases O2

Oxygen

O2 released when water is split

NADP+

Molecule that is reduced to form NADPH

Carbon fixation

First phase of the Calvin cycle where CO2 enters the cycle

Rubisco

Enzyme that catalyzes carbon fixation

RuBP

CO2 acceptor used in the Calvin cycle

Reduction

Second phase of the Calvin cycle

G3P

Three-carbon sugar produced by the Calvin cycle

Regeneration

Third phase of the Calvin cycle that regenerates RuBP

Calvin cycle inputs

CO2

Calvin cycle output

G3P

Three phases of the Calvin cycle

Carbon fixation

One G3P production

Calvin cycle occurs three times and fixes three CO2 molecules

Light reaction flow

Photosystem II → electron transport chain → Photosystem I

Light reaction products

ATP

Light reaction location

Thylakoid membrane

Calvin cycle location

Stroma

Oxidized in photosynthesis

H2O is oxidized

Reduced in photosynthesis

CO2 is reduced

Purpose of photosynthesis

Store solar energy as chemical energy in organic molecules

Photosynthesis and oxygen

Photosynthesis produces the O2 in our atmosphere

Photosynthesis and sugar

Sugar made in chloroplasts provides chemical energy and carbon skeletons for cells