Chapter 9: Cellular Respiration

1. Chapter 9: Cellular Respiration Ferguson This is a summary of what is needed to explain the overall processes. For in depth descriptions of the stages in the process, refer to section 9.2 notes from the text.

2. Chemical Energy and Food • We eat because food provides our bodies with energy. • Calorie = amount of energy needed to raise 1 gram of water 1 degree Celsius. • Cells don’t actually “burn” calories from molecules like glucose. • Instead, they gradually release the energy.

3. Overview of Cellular Respiration • Process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. • 6O2 + C6H12O6  6CO2+ 6H2O + Energy • How does this compare to Photosynthesis??

4. Overview of Cellular Respiration • There are 3 main stages: • Glycolysis • Krebs Cycle • Electron Transport Chain • Each stage captures some chemical energy in the cell, and uses it to produce ATP.

5. Glycolysis • Process in which one molecule of glucose is broken in half, producing two molecules of pyruvic acid. • Occurs in the cytoplasm. • Uses the energy from 2 ATP molecules to produce 4 ATP molecules. • What is the net gain of ATP?

6. Glycolysis • Uses the electron carrier NAD+ , which becomes NADH. • Can produce thousands of ATP a seconds. • Does NOT require oxygen. (Anaerobic)

7. Fermentation • Releases energy from food molecules in the absence of oxygen. • Alcoholic Fermentation – used by yeasts • Pyruvic Acid + NADH  alcohol + CO2 + NAD+ • Lactic Acid Fermentation – muscle cells, bacteria used in dairy products. • Pyruvic Acid + NADH  lactic acid + NAD+ • Both types of fermentation regenerate NAD+ that can be used in Glycolysis.

8. Instead of Fermentation… • At the end of Glycolysis, about 90% of the energy in glucose is still unused, locked away in the bonds of pyruvic acid. • To release the remaining energy, cells must use oxygen. • The next 2 steps of cellular respiration are said to be aerobic.

9. The Krebs Cycle • Pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. • Begins when a molecule of pyruvic acid enters the mitochondria. • After many reactions, the pyruvic acid becomes CO2, NADH is formed, ATP is formed, and another electron carrier, FADH2 is formed.

10. The Krebs Cycle • CO2 is released when we exhale. • ATP is used to power the cell’s activities. • In the presence of oxygen, the electron carriers NADH and FADH2 are used to create even greater amounts of ATP.

11. Electron Transport Chain • Uses high-energy electrons from the Krebs cycle to convert ADP to ATP. • The chain is composed of a series of proteins throughout the membranes of the mitrochondria. • These proteins pump H+ ions through the membrane, which powers ATP Synthase to convert ADP to ATP.

12. Electron Transport Chain

13. The Totals • Glycolysis alone can only produce 2 net ATP. • In the presence of oxygen, Cellular Respiration can produce 36 molecules of ATP.

14. Energy and Exercise • Quick Energy • When athletes only need energy for a quick burst (~90 seconds), they resort to the energy from Glycolysis and Lactic Acid Fermentation. • Long-Term Energy • When athletes need energy for an extended period of time, cellular respiration is the only way to provide continuous energy.

16. Make your own concept map: • Using the following terms, create a concept map that describes the process of cellular respiration. 2 ATP2 ATP36 ATP6 NADH2 FADHElectron transport chainMitochondrionCytoplasmFermentationGlycolysisGlucosePyruvateLactic acidKreb's Cycle

17. Book Review • Answer the following questions on page 237: • 1-10 • 12, 13, 14, 19, 20, 22.