CHAPTER 7 PHOTOSYNTHESIS: USING LIGHT TO MAKE FOODGeneral Biology

CM Lamberty

BIOLOGY AND SOCIETY

Green Energy Wood…fossil fuels….biomass/biofuels Renewable, less S, wildlife habitats, reduce

erosion, disversification 4% of all E in US

THE BASICS OF PHOTOSYNTHESIS

Process by which plants, algae and certain bacteria transform light E into chemical E

Uses CO2 and H2O as starting materials Chemical E then stored in bonds of sugar Plants = autotrophs

CHLOROPLASTS: SITES OF PHOTOSYNTHESIS

Chloroplasts: Found

Chlorophyll

Stomata: Stroma: Thylakoids: Grana:

THE OVERALL EQUATION FOR PHOTOSYNTHESIS

6 CO2 + 6 H2O C6H12O6 + 6 O2

CO2 and H2O were waste products of cell. resp

A PHOTOSYNTHESIS ROAD MAP

2 stages of photosynthesis Light Reactions

Calvin Cycle

THE LIGHT REACTIONS: SOLAR…CHEMICAL

THE NATURE OF SUNLIGHT

Radiation Electromagnetic energy Waves Wavelength

EM spectrum

Light hits object and is either absorbed or reflect

CHLOROPLAST PIGMENTS

Chlorophyll a

Chlorophyll b

Carotenoids

HOW PHOTOSYSTEMS HARVEST LIGHT E

Photon: Shorter wavelength Pigment MQ absorb photon

Thylakoid membrane

HOW LIGHT RXNS GENERATE ATP & NADPH

2 types of photosystems cooperate Water-splitting photosystem

Transfer between systems

NADPH-producing photosystem

HOW LIGHT RXNS GENERATE ATP & NADPH

Light reactions taking place in thylakoid membrane

2 photosystems and electron transport chain

ATP production is similar to cellular respiration

Difference:

THE CALVIN CYCLE: MAKING SUGAR FROM CO2

Sugar factory within stroma of chloroplast Cycle: starting material regenerated each

turn

SOLAR DRIVEN EVOLUTION

Hot, dry climates plants continue photosynthesis while conserving water

C4

CAM