PHOTOSYNTHESIS

I. Autotrophs and Heterotrophs SUN A. Energy for living things comes from the SUN B. Plants and other organisms use light energy from the sun to produce food C. Autotrophs- make their own food »Ex: plants

D.Heterotrophs- cannot use sun energy to make their food and obtain it from the foods they consume »Ex: leopards, mushrooms

II. Chemical Energy and ATP A. To live, organisms must release energy in sugars and other compounds

B. ATP »adenosine triphosphate »chemical compound used to store energy

C. Releasing energy from ATP -> Stored energy is released from ATP when ATP is broken down into ADP + Phosphate -> Add/subtract Phosphate and you can store/release ENERGY!

D. When is ATP used? »Active transport »Powers movement inside cell: microtubules use energy

III. Light & Pigments LIGHT CHLOROPHYLL A. Photosynthesis requires LIGHT and CHLOROPHYLL, a molecule in chloroplasts, in addition to water & CO 2 B. Sunlight is “white” but contains mixtures of visible wavelengths PIGMENTS C. Plants gather sun’s energy using light- absorbing molecules called PIGMENTS

D. Leaves absorb blue-violet & red-orange light very well E. Green light is reflected- why plants look green!

Chlorophyll a - Absorbs all colors of light except green - Plays major role in light reactions of photosynthesis Chlorophyll b - Appears yellow-green - Absorbs additional light Xanthophyll - In carotenoid family - Yellow - Fat soluble Carotene - Accessory pigments - Red & orange pigments Major Pigments- use light energy directly Accessory Pigments- pass absorbed light energy to chlorophyll

IV. LOCATION OF PHOTOSYNTHESIS

V. Role of Pigments A. When chlorophyll absorbs light, much of the energy is transferred to raising the ENERGY LEVEL in the CHLOROPLASTS

B. EQUATION Inputs: Light, carbon dioxide, & water Outputs: sugar and oxygen

** Chloroplast has double membrane ** Thylakoids: sac-like photosynthetic Thylakoids: sac-like photosynthetic membranes membranes –Arranged in stacks called GRANA –Have clusters of chlorophyll and other pigments Stroma: Fluid area surrounding Stroma: Fluid area surrounding thylakoids thylakoids CHLOROPLAST STRUCTURE

* Light-Dependent: takes place in takes place in thylakoids thylakoids * Calvin Cycle: takes place in takes place in stroma stroma

Light Reaction 1.Chlorophyll molecules in thylakoid capture light energy 2.This energy releases electrons from H 2 O 3.H 2 O then splits into O 2 and H+ 4.Oxygen is a "waste product" & escapes to the atmosphere

So what happens to the electrons and hydrogen ions? Chloroplasts use them to make an energy-rich molecule called NADPH and ATPChloroplasts use them to make an energy-rich molecule called NADPH and ATP The overall result of the light reaction?The overall result of the light reaction? Light Oxygen + NADPH + ATP

ATP and NADP are recycled back into the systemATP and NADP are recycled back into the system Light reaction is charging up the “battery” needed to synthesize sugars in Calvin CycleLight reaction is charging up the “battery” needed to synthesize sugars in Calvin Cycle

Calvin Cycle Does NOT use light at allDoes NOT use light at all Process to store energy that was made in light cycle in the form of sugarProcess to store energy that was made in light cycle in the form of sugar

1.The enzymes for the Calvin cycle are located outside the thylakoids dissolved in the STROMA. 2.Uses CO 2 and energy powered by ATP and NADPH to produce sugar 3.NAPDH and ATP are recycled back to the Light Cycle for “recharging” The Calvin Cycle

Reactants: Products:

Two Processes Light Reaction Calvin Cycle

Factors Affecting Photosynthesis Shortage of raw materialsShortage of raw materials TemperatureTemperature Light intensityLight intensity