7.3

Question 1

Define feedback inhibition

Answer 1

The most common mechanism for metabolic control. end product binds to allosteric site on enzyme in the pathway

Question 2

Identify the two key control points for regulation of respiration

Answer 2

• In glycolysis
   Phosphofructokinase is allosterically inhibited by ATP and/or citrate
• In pyruvate-oxidation/Citric acid cycle
   Pyruvate dehydrogenase inhibited by high levels of NADH

Question 3

aerobic respiration

Answer 3

use of oxygen as final electron acceptor

• Glycolysis, citric acid cycle & oxidative phosphorylation
• NAD+ and FAD accept electrons
• Electrons are transferred to the ETC
• PRODUCES 32 ATP PER GLUCOSE MOLECULE

Question 4

anaerobic respiration

Answer 4

 Use of inorganic molecules (other than oxygen) as a final electron acceptor
 Many prokaryotes use sulfur, nitrate, carbon dioxide or even inorganic metals

Question 5

define fermentation

Answer 5

• Use of organic molecules as final electron acceptor
• Consists of GLYCOLYSIS plus reactions that regenerate NAD+, which can be reused by glycolysis
• 2 types
  -ethanol and lactic acid fermentation
• Glycolysis
• NAD+ accepts electrons during glycolysis
• Organic molecule is final electron acceptor
• PRODUCES 2 ATP PER GLUCOSE MOLECULE

Question 6

Ethanol fermentation

Answer 6

 Pyruvate is converted to ethanal in 2 steps
* Releases carbon dioxide
* Produces ethanol
 Found in yeast
 Used in brewing, winemaking & baking

Question 7

Lactic acid fermentation

Answer 7

 PYRUVATE IS REDUCED BY NADH TO REGENERATE NAD+, forming lactate as an end product with no release of carbon dioxide
 Found in
* Some fungi and bacteria
 Used to make cheese and yogurt
 Human muscle cells when oxygen is scarce

Question 8

Use examples to identify the interactions of other macromolecules with glycolysis and the citric acid cycle