1. Michael Slemp

2. Review of Cellular Respiration 1.Where does glycolysis happen? Is it aerobic or anaerobic process? 3. Where does cellular respiration happens? Is it aerobic or anaerobic process? 2. What is the final product of glycolysis? 4. Name the 2 steps of cellular respiration? Where does each step happen? 5. What are the final products of each step? Cytoplasm, anaerobic process Two 3-carbon molecules (pyruvate), 2 ATP Mitochondria, aerobic process 1. Krebs cycle – matrix of mitochondria. 2- electron transport – inner membrane of mitochondria 1- small amounts of ATP, other energy-carrying molecules, co2 2-large number of ATP, water, heat

3. Glycolysis glucose Two 3-carbon molecules 2 ATP molecules Oxygen present Cellular Respiration Large amount of ATP produced. aerobic Oxygen NOT present anaerobic Fermentation

4. In order to understand fermentation we need to look at glycolysis a little bit closer We said that the final product of glycolysis are two 3-carbon molecules and 2 molecules of ATP During the splitting of glucose more energy is released that 2 molecules of ATP can capture Remember ? ATP = $1.00 bill This extra energy is captured into other energy-carrying molecule (NAD+) Remember ? During Krebs cycle, energy-carrying molecules were also formed. These were our $20.00 bills which entered electron transport for creation of ATP?

5. Glycolysis glucose Two 3-carbon molecules (2 pyruvates) + 2 ATP + extra energy Packed into NAD+ molecule NAD+ + extra energy = NADH Energy-poor molecule (pennies) Energy-rich molecule ($20.00), too large for cell use

6. Cellular respiration only happens during the presence of oxygen. So what would happen in anaerobic conditions, when products of glycolysis cannot enter process of cellular respiration ? Finally, all NAD+ would be used up, cell could not produce no more ATP in glycolysis and would die. That is why, in anaerobic conditions, cell enters process of fermentation!

7. FERMENTATION Anaerobic process Does not produce more ATP Recycles NAD+ (which makes possible for glycolysis to continue) Without fermentation, glycolysis would stop Different cells (like yeast, plants) use different type s of fermentations. Why is this important? Think of cheese, bread, yogurt, wine, alcohol… The taste and texture of fermented food is based on the final product of fermentation. E.g. alcohol fermentation = alcohol

8. For example: Lactic acid fermentation Glucose Two 3-carbon molecules (pyruvates ) 2 ATP NAD+ + energy = NADH 2 lactic acid molecules NADH = energy + NAD+ Glycolysis Fermentation This process is used by our muscle cell during strenuous exercise (when not enough O2). Lactic acid causes muscle burning. energy Waste product = lactic acid (sour taste in milk and yogurt)

9. Another example: Alcoholic fermentation 2 alcohol molecules Glycolysis Fermentation Waste product: alcohol and carbon dioxide Pyruvate + 2 CO2 (carbon dioxide) Yeast use alcoholic fermentation during the production of bread. CO2 causes the dough to puff up and rise. During baking, CO2 evaporates into air and yeast is killed by heat of baking.