PHOTOSYNTHESIS

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

Heterotrophs- obtain it from the foods they consume » Ex: animals, some bacteria, protozoans (and even fungi!)

Sooo… food as energy is either MADE through photosynthesis or OBTAINED through consumption

II. Light & Pigments A.In addition to water & CO 2, LIGHT photosynthesis requires LIGHT and CHLOROPHYLL CHLOROPHYLL, a molecule in chloroplasts B.Sunlight is “white” but contains mixtures of visible wavelengths

C. Visible energy spans wavelengths of approx nm D. It is part of the electromagnetic spectrum

PIGMENTS E. Plants gather sun’s energy using light- absorbing molecules called PIGMENTS F. Leaves blue-violet & red-orange light very well G. Green light is REFLECTED why plants look green! ABSORB

Plant pigments absorb different wavelengths of energy- which wavelength is the LEAST absorbed? Green is NOT absorbed!

H. Plant Pigments Chlorophyll a - Absorbs all colors of light except green - Plays major role in light reactions of photosynthesis Chlorophyll b - Yellow-green Xanthophyll - In carotenoid family - Yellow Carotene - Red & orange pigments MAJOR MINOR

III. Role of Pigments A.When chlorophyll absorbs light, much of the energy is transferred to raising of the energy is transferred to raising the energy level of ELECTRONS in the energy level of ELECTRONS in the CHLOROPLASTS the CHLOROPLASTS B. These electrons power photosynthesis

Think about the Location of Photosynthesis…

Location of Photosynthesis Which tissues contain chloroplasts?

Other Important Parts Xylem: transports H 2 O Stoma: pore that allows gases to enter and exit

A.Double-membrane structure 1  outer membrane 2  inner membrane 3  granum (stack) 4  Thylakoid (individual) 5  Stroma (fluid) I. CHLOROPLAST STRUCTURE Thylakoids: photosynthetic membranes that have clusters of chlorophyll II and other pigments Grana are stacks of thylakoids Stroma: Fluid surrounding thylakoids

Photosynthesis Has Two Parts:

D. PHOTOSYNTHESIS Inputs: Light, carbon dioxide, & water Outputs: sugar and oxygen

II. Chemical Energy & ATP A. ATP (adenosine triphosphate) is an organic molecule that is a source of potential energy for all cells.

Using Biochemical energy ATP is useful to all types of cells as their basic energy source When is ATP used? »Active transport »Powers movement inside cell: microtubules use energy

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

III. Light Reaction

B. So what happens to the electrons and hydrogen ions? 1.Chloroplasts use them to make energy- rich molecules called NADPH and ATP rich molecules called NADPH and ATP 2.The overall result of the LIGHT reaction only? Light + Chlorophyll + H 2 O Oxygen + NADPH + ATP

3.ADP and NADP+ are recycled back into the system 4.Light reaction is charging up the “battery” needed to synthesize sugars in Calvin Cycle needed to synthesize sugars in Calvin Cycle

IV. Calvin Cycle A.Does NOT use light at all B.This is the process to use energy from Light Cycle to convert CO 2 into glucose

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.NADP+ and ADP are recycled back to the Light Cycle for “recharging” C. The Process

Reactants: Products:

Two Processes Light Reaction Calvin Cycle

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