1. Cellular Respiration Chemical Pathways Section 9-1 Allen Biology I

2. Chemical Energy and Food Lots of energy present in food (glucose/other compounds) – Ex: 1 gram glucose = 3811 calories – Calorie – amount of energy required to raise one gram of water, one Celsius degree – Cells release the energy in glucose and other food compounds

3. Overview of Cellular Respiration “reverse photosynthesis” – 6O 2 + C 6 H 12 O 6 → 6CO 2 + 6H 2 O + energy Cellular respiration – process of breaking down glucose and other food molecule in the presence of “oxygen” Figure 9-2 (page 222)

4. Cellular Respiration

5. Glycolysis Glycolysis – one molecule of glucose is broken in half, producing two molecules of pyruvic acid and a 3-carbon compound See figure 9-3(page 223)

6. Glycolysis Key concepts: – Occurs in the cytoplasm of cell – No oxygen required for glycolysis to occur – Glucose is broken down into two 3-carbon pyruvates (pyruvic acid) – Net production of 2 ATP, 2 NADH, and 2 pyruvate molecules

7. Fermentation Cellular respiration will NOT occur (Krebs and ETC) if oxygen is not present If oxygen is not present, fermentation will occur Fermentation – releasing of energy from food molecules by producing ATP in the absence of oxygen

9. 2 Types of Fermentation Alcoholic Lactic acid

10. Alcoholic Fermentation Pyruvic acid + NADH → alcohol + CO 2 + NAD Causes bread to rise “anaerobic” – no oxygen present

11. Lactic Acid Fermentation Pyruvic acid is converted into lactic acid Pyruvic acid + NADH → lactic acid + NAD Ex: muscle cells – Not enough ATP produced to lack of oxygen – Cells begin to produce ATP by lactic acid fermentation