Biology: Respiration and Fermentation

Review RESPIRATION AEROBIC ANAEROBIC Uses O2 Doesn’t use O2 Good for cardio exercises Good for short bursts of energy Happens in body cells Happens in muscle cells Also called Kreb’s Cycle Also called fermentation

Types of Fermentation Two common types are alcohol fermentation and lactic acid fermentation Alcohol is produced by plant cells Lactic acid is produced by animal cells Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Alcohol Fermentation In plant cells without oxygen, the pyruvate is broken down by fermentation. (Pyruvate is the output from the metabolism of glucose) This process produces CO2 and alcohol, along with a small amount of ATP This process is used in baking and to produce alcoholic beverages.

Fermentation in Plants produces Ethanol (Alcohol) Without O2 present, pyruvate produced in plant cells will ferment. It will give off CO2 (which causes bread to rise) and ethanol (alcohol).

Fermentation in Animal Cells produces Lactic Acid Without O2 present in animal cells, pyruvate will be broken down to form lactate (lactic acid). This is the substance that makes muscles burn during intense exercise. Humans can break down the lactic acid further to produce a little more ATP when O2 is scarce.

Lactic Acid Fermentation in Some Yeasts and Bacteria Some yeasts and bacteria also produce lactic acid from fermentation. Lactic acid from these sources produces yogurt and cheese.

Comparing Fermentation and Aerobic Cellular Respiration Both processes break down glucose to release energy. Fermentation produces 2 ATP per glucose, Aerobic Cellular Respiration produces 38 ATP Electrons from glucose go to either lactic acid or alcohol in fermentation Electrons from glucose go to Oxygen in Cellular Respiration.