Chapter 6: Photosynthesis & Chapter 7: Cellular Respiration

I. Energy and Living Things – A. Building Molecules That Store Energy 1. Autotrophs make their own food by using energy from sunlight or inorganic substances to build organic compounds. 2. Many autotrophs make food by the process of photosynthesis.

B. Breaking Down Food for Energy – 1. Energy from sunlight flows through living systems, from autotrophs to heterotrophs. – 2. Heterotrophs release the energy in food through the process of cellular respiration.

C. Transfer of Energy to ATP – 1. Cellular respiration releases much of the energy in food to make ATP, the energy “currency” inside cells. – 2. Enough energy is released from ATP to drive most of a cell’s activities.

D. ATP Releases Energy – 1. ATP supplies cells with energy needed for metabolism. – 2. Energy is released upon the breakdown of ATP to ADP. H ATP  ADP + P + energy

II. Photosynthesis – A. Using the Energy in Sunlight 1. The 3 Stages of Photosynthesis – a. First, energy is captured from sunlight. – b. Second, energy is temporarily stored in ATP and NADPH. – c. Third, organic compounds are made using ATP, NADPH, and carbon dioxide.

B. Stage One: Absorption of Light Energy – 1. Pigments- such as chlorophyll, absorb light energy during photosynthesis. – 2. Production of Oxygen- During photosynthesis, water molecules are split to release oxygen by an enzyme inside structures called thylakoids.

C. Stage Two: Conversion of Light Energy – 1. Electron Transport Chains- Electrons excited by light travel through electron transport chains, in which ATP and NADPH are produced.

D. Stage Three: Storage of Energy – 1. Calvin Cycle- Through carbon dioxide fixation, often by the Calvin cycle, carbon dioxide in the atmosphere is used to make organic compounds, which store energy. – 2. Factors that Affect Photosynthesis by the environmental a. the intensity of light b. the concentration of carbon dioxide c. the temperature

III. Cellular Respiration A. Cellular Energy – 1. The Stages of Cellular Respiration a. There are two stages. – 2. Glycolysis a. Is the first stage of cellular respiration

B. Stage One: Breakdown of Glucose – 1. Aerobic and Anaerobic Respiration a. The second stage of cellular respiration is either 1. aerobic respiration (in the presence of oxygen) or 2. anaerobic respiration (in the absence of oxygen). 3. A large amount of ATP is made during aerobic respiration. 4. NAD+ is recycled during the anaerobic process of fermentation. 2. Glycolysis- Glucose is broken down to pyruvate during glycolysis, making some ATP.

C. Stage Two: Production of ATP – 1. Krebs Cycle- is a series of reactions that produce energy- storing molecules during aerobic respiration. – 2. Electron Transport Chain- During aerobic respiration, large amounts of ATP are made in an electron transport chain.

D. Fermentation in the Absence of Oxygen – 1. Fermentation When oxygen is not present, fermentation follows glycolysis, regenerating NAD+ needed for glycolysis to continue. – 2. Lactic Acid Fermentation a. Pyruvate is converted to lactate. – 3. Alcoholic Fermentation- pyruvate is broken down to ethanol, releasing carbon dioxide. – 4. Production of ATP although a small amount of ATP is made during fermentation, most of a cell’s ATP is made during aerobic respiration.