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Ch. 6 Cellular Respiration. 6.14 – 6.15. Review: Each molecule of glucose yields many molecules of ATP. Where do glycolysis & Krebs cycle take place & how much ATP do they make? Cytoplasm & mitochondrial matrix, 2 ATP each= 4 total What energy source carries energy to the ETC? NADH & FADH2
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Ch. 6 Cellular Respiration 6.14 – 6.15
Review: Each molecule of glucose yields many molecules of ATP • Where do glycolysis & Krebs cycle take place & how much ATP do they make? • Cytoplasm & mitochondrial matrix, 2 ATP each= 4 total • What energy source carries energy to the ETC? • NADH & FADH2 • Because most ATP is generated from ETC which depends heavily on O2, if there was no O2 what would happen to cell? • It would starve from lack of energy and may die.
Fermentation is an anaerobic alternative to aerobic respiration • How can yeast survive in an anaerobic environment? • Glycolysis, uses no O2, provides 2 ATP, enough energy to survive • How does the yeast replenish the NAD+ used in glycolysis? • Alcohol fermentations is the process that regenerates NAD+ • How do humans use this process to their advantage? • CO2 makes bubbles for beer, sparkling wine & ethanol from glucose. • How does this keep glycolysis working? • CO2 is removed, NADH is oxidized, recharging the cell with NAD+ and forming ethanol (energy rich)
What is another type of fermentation that happens in many cells (including fast muscle fibers of animals)? • Lactic Acid Fermentation • How does this happen? • lactic acid is produced when NADH is oxidized back to NAD+ • What happens to the CO2? • The ATP production is the same (from glycolysis) but no CO2 is given off & lactic acid retains all 3 carbons from pyruvic acid. • What happens to the lactic acid? • Converted back to pyruvic acid when O2 is present. (Dairy industry uses lactic acid fermentation from bacteria to make cheese and yogurt)
What is a strict anaerobe? • Not a mean bacteria but a bacterial that must live in stagnant ponds or deep in soil (for them oxygen is poison) • What is a facultative anaerobe? • Yeast, E. coli or other bacteria that can make ATP by chemiosmosis or fermentation, depending if O2 is available. • How is pyruvic acid special? • If O2 is available yeast will use this more efficient process (aerobic respiration), that is why to make beer & wine yeast must be grown anaerobically, to ferment sugars & make ethanol (see gas valves venting off excess CO2 & keeping air out.