3bio6

Question 1

Fermentation
-why it is done
-two types of fermentation

Answer 1

In the absence of oxygen the ETC does not happen. Without the ETC, NADH can’t lose its electrons and become NAD+ again. NAD+ is needed for glycolysis because it oxidizes G3P. The solutions are ethanol and lactic acid fermentation. ethanol fermentation has two steps. First the pyruvates are decarboxylated into acetaldehyde. In step two NADH is oxidized to NAD+ making ethanol. it is poisonous to yeast and must be eliminated. lactic acid fermentation happens in the cytosol. In it NADH is oxidized to make the waste product lactic acid. Both pathways yeild two atp per glucose, but since NAD+ is regenerated glycolysis can continue.

Question 2

Metabolic pathways for macromolecules besides sugars
-triglycerides
-proteins

Answer 2

Macromolecules are broken down into monomers and fed into respiration at different points. Triglycerides are broken down into the glycerol that becomes G3P and fatty acids that become acetyl coAs. Entering glycolysis as G3Ps bypasses only the consumption of atp. The process of turning fatty acids into acetyl coAs is called beta oxidation. Proteins are broken down into amino acids. The amino group from each is converted into urea. The rest enters respiration as a pyruvate, acetyl coA, or Krebs intermediate depending on the r group.