Chapter 10 - Photosynthesis

Chapter 10 - Photosynthesis - Chapter 10 Class Notes...

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Chapter 10 Class Notes – Photosynthesis – Page 1 Max Sauberman AP Biology – Mr. Schilp Chapter 10 Photosynthesis Photosynthesis: Photosynthesis is the process that converts solar energy into chemical energy. Directly or indirectly, photosynthesis feeds the biosphere; nourishing almost the entire living world. In photosynthesis, plants can transfer energy from a star (in a completely different system) to food. Photosynthesis occurs in plants, algae, certain other protists, and some prokaryotes. Autotrophs: Autotrophs sustain themselves without eating anything derived from other organisms. Autotrophs are the producers of the biosphere, producing organic molecules from CO 2 and other inorganic molecules. Almost all plants are photoautotrophs, using the energy of sunlight to make organic molecules from water and carbon dioxide. Heterotrophs: Heterotrophs obtain their organic material from other organisms. Heterotrophs are the consumers of the biosphere. Almost all heterotrophs, including humans, depend on photoautotrophs for food and oxygen. Chloroplasts: Chloroplasts are organelles that are responsible for feeding the vast majority of organisms. Chloroplasts are present in a variety of photosynthetic organisms. Leaves are the major locations of photosynthesis; their green color is from chlorophyll, the green pigment within chloroplasts. Leaves have a large surface area and have the closes exposure to the Sun. Light energy absorbed by the chlorophyll drives the synthesis of organic molecules in the chloroplast. Through microscopic pores called stomata, CO 2 enters the leaf and O 2 exits. Components of the Chloroplast: Chloroplasts are found mainly in cells of the mesophyll, the interior tissue of the leaf.
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Chapter 10 Class Notes – Photosynthesis – Page 2 A typical mesophyll cell has 30-40 chloroplasts. The chlorophyll is in the membranes of thylakoids, which may be stacked in columns called grana. Chloroplasts contain stroma, a dense fluid. Tracking Atoms through Photosynthesis: Photosynthesis can be summarized in 6 CO 2 + 12 H 2 O + light energy C 6 H 12 O 6 + 6 O 2 + 6 H 2 O The Splitting of Water: Chloroplasts split water into hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules. Photosynthesis as a Redox Process: Photosynthesis is a redox process in which water is oxidized and carbon dioxide is reduced. The Two Stages of Photosynthesis: Photosynthesis consists of the light reactions and the Calvin cycle. The light reactions, in the thylakoids, split water, release O 2 , produce ATP and form NADPH. The Calvin cycle (named after Melvin Calvin), in the stroma, forms sugar from CO 2 using ATP and NADPH. The Calvin cycle begins with carbon fixation, incorporating CO 2 into organic molecules. The Light Reactions:
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This note was uploaded on 03/17/2011 for the course BIO 101 taught by Professor Sullivan during the Spring '08 term at Harvard.

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Chapter 10 - Photosynthesis - Chapter 10 Class Notes...

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