Fermentation Sections 6.13-6.16

6.13 Fermentation Fermentation is a way of harvesting chemical energy that does not require oxygen. Fermentation takes advantage of glycolysis, produces two ATP molecules per glucose, and reduces NAD+ to NADH. Fermentation must provide an anaerobic path for recycling NADH back to NAD+. © 2012 Pearson Education, Inc. 2

6.13 Lactic acid Fermentation Your muscle cells (when?) and certain bacteria can oxidize NADH through lactic acid fermentation, in which NADH is oxidized to NAD+ and pyruvate is reduced to lactate. © 2012 Pearson Education, Inc. 3

Glucose 2 ADP 2 NAD 2 P Glycolysis 2 ATP 2 NADH 2 Pyruvate 2 NADH Figure 6.13A Glucose 2 ADP 2 NAD 2 P Glycolysis 2 ATP 2 NADH 2 Pyruvate 2 NADH Figure 6.13A Lactic acid fermentation: NAD+ is regenerated as pyruvate is reduced to lactate. 2 NAD 2 Lactate 4

6.13 Lactic Acid Fermentation Lactate is carried by the blood to the liver, where it is converted back to pyruvate and oxidized in the mitochondria of liver cells. Bacteria: What foods are produced by lactic acid fermentation? © 2012 Pearson Education, Inc. 5

In this process yeasts (single-celled fungi) 6.13 Fermentation Alcohol Fermentation In this process yeasts (single-celled fungi) oxidize NADH back to NAD+ and convert pyruvate to CO2 and ethanol. What foods are produced by alcohol fermentation? © 2012 Pearson Education, Inc. 6

Glucose 2 ADP 2 NAD Glycolysis 2 P 2 ATP 2 NADH 2 Pyruvate 2 NADH Figure 6.13B Glucose 2 ADP 2 NAD 2 P Glycolysis 2 ATP 2 NADH 2 Pyruvate Figure 6.13B Alchohol fermentation: NAD is regenerated as pyruvate is broken down to CO2 and ethanol. 2 NADH 2 CO2 2 NAD 2 Ethanol 7

Facultative anaerobes 6.13 Fermentation Obligate anaerobes Facultative anaerobes © 2012 Pearson Education, Inc. 8

The ancient history of glycolysis is supported by its 6.14 EVOLUTION CONNECTION: Glycolysis evolved early in the history of life on Earth The ancient history of glycolysis is supported by its occurrence in all the domains of life and Uses pathways that do not involve any membrane-bounded organelles. © 2012 Pearson Education, Inc. 9

6.15 Cells use many kinds of organic molecules as fuel for cellular respiration Although glucose is considered to be the primary source of sugar for respiration and fermentation, ATP is generated using carbohydrates, fats, and proteins. © 2012 Pearson Education, Inc. 10

Pyruvate Oxidation Acetyl CoA Oxidative Phosphorylation Figure 6.15 Food, such as peanuts Carbohydrates Fats Proteins Sugars Glycerol Fatty acids Amino acids Amino groups Figure 6.15 Pathways that break down various food molecules Citric Acid Cycle Pyruvate Oxidation Acetyl CoA Oxidative Phosphorylation Glucose G3P Pyruvate Glycolysis ATP 11