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Anaerobic Pathways

Anaerobic Pathways. Organisms use these pathways in oxygen-poor environments such as Wet environments Human digestive tract Deep underground. Organisms in these environments can obtain energy from glycolysis in a limited way Step 6 (G3P to BPG) reduces NAD + to NADH.

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Anaerobic Pathways

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  1. Anaerobic Pathways

  2. Organisms use these pathways in oxygen-poor environments such as • Wet environments • Human digestive tract • Deep underground

  3. Organisms in these environments can obtain energy from glycolysis in a limited way • Step 6 (G3P to BPG) reduces NAD+ to NADH. • If no oxidation of NADH occurs due to lack of oxygen, NAD+ will be limited thus stopping glycolysis. • Some organisms have a different route of oxidizing NADH called fermentation. • Bacteria have many different routes • Eukaryotes have 2 methods

  4. Fermentation in Eukaryotes • The two methods of fermentation in Eukaryotes are: • Ethanol fermentation • Lactic Acid Fermentation (Lactate fermentation)

  5. Ethanol Fermentation = alcohol fermentation. • Glucose undergoes glycolysis to produce 2 pyruvates, 2NADH + 2H+ and 2 ATP net. • The 2 pyruvates are decarboxylated and form 2 acetalaldedydes. • The two acetalaldedydes are reduced by 2NADH from glycolysis forming 2 ethanols and 2 NAD+ • CO2 and ethanol are waste products • Example of an organism that carry out ethanol fermentation is yeast.

  6. Alcohol Fermentation One of main function is to resupplies glycolysis with NAD+

  7. Uses of alcohol Fermentation • Humans use alcohol fermentation to make breads, pastries, beers, wines, liquor and soy sauce. • These are products of fermentation. • Accumulation of ethanol in an organism can cause death.

  8. Lactate Fermentation • During exercise, muscles respire faster than the body can supply oxygen. • Oxidative respiration slows down and lactic acid fermentation begins • Glucose undergoes glycolysis to produce 2 pyruvates, 2NADH + 2H+ and 2 ATP net. • The 2 pyruvates are reduced by 2NADH from glycolysis forming 2 lactates and 2 NAD+ • NAD+ generated goes back to glycolysis • Lactate accumulates

  9. Lactate Fermentation

  10. Accumulation of lactate causes stiffness, soreness and fatigue • This reaction is reversible • When exercises cease, andoxygen is present: • Lactate is shuttled to liverto be oxidized. • Pyruvate and NADH are replenished • Pyruvate gets into the mitochondria where it undergoes aerobic cellular respiration.

  11. Homework • Pg. 194: # 1-4, 6, 7

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