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Chapter 6

I. Photosynthesis: Capturingand Converting Energy

A. Importance ofPhotosynthesis1. Provides carbon for

organic compounds.2. Provides stored

energy (glucose) forthe synthesis oforganic compoundsand other cellactivities.

3. Provides Oxygen.4. Keeps CO2 levels

down.

CO2 O2

Photosynthesis

Respiration

Sunlight

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B. Photosynthesis6CO2 + 6H2O + light C6H12O6 + 6O2

C. Autotrophs andHeterotrophs1. Autotrophs

a. Use a source of energy, such as sunlight,to produce food from inorganic molecules.

b. Plants, some bacteria.

2. Heterotrophsa. Obtain energy from the food they eat.

i. Autotrophs, other heterotrophs, organic wastes

b. Animals, fungi, bacteria.

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D. Pigments

1. Pigments –colored substanceswhich absorb light.

2. Chlorophyll is theprimary pigmentutilized inphotosynthesis.

3. Light energy isnecessary forphotosynthesis.

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D. Pigments

4. The color we see inautumn are thosepigments which aremasked bychlorophyll.

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E. Energy-Storing Compounds

1. How does a plant trap theenergy from sunlight?a. Energy from the sunlight is

transferred to electrons.b. Chlorophyll acts like a solar

cell. Energy from light istrapped and transferred toelectrons.

c. The high energy electrons aretrapped in chemical bonds

E. Energy-Storing Compounds

2. NADP+ + 2e- + H+ NADPHa. NADPH is an electron carrierb. The Hydrogen and the electrons from

NADPH are used to build sugars.

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E. Energy-Storing Compounds

3. AMP + 2Pi ATP4. ATP = Adenosine

Triphosphatea. Provides energy for

cellular activities.b. The energy is used

during photosynthesis tobuild sugars.

c. The energy is storedbetween the bonds ofthe phosphate groups.