[12.4] anaerobic respiration

Question 1

what happens when oxygen becomes unavailable?

Answer 1

• krebs cycle and ETC cannot continue as all FAD and NAD will be reduced
• no FAD or NAD will be available to take up H⁺ produced during krebs so enzymes stop working
• this leaves only the anaerobic process of glycolysis as a potential source of ATP

Question 2

what are the 2 types of anaerobic respiration that will occur in eukaryotic cells?

Answer 2

• conversion of pyruvate to ethanol and carbon dioxide in plants
• convertion of pyruvate to lactate in animals

Question 3

describe the process of production of ethanol in plants via fermentation

Answer 3

• glucose -> 2 pyruvate (2 ATP released, 2 NAD -> 2NADH)
• 2 pyruvate -> 2 ethanal [2C] (2 CO₂ released)
• 2 ethanal -> 2 ethanol [2C], which is excreted

Question 4

describe the summary equation for fermentation

Answer 4

pyruvate + NADH ➞ ethanol + carbon dioxide + NAD⁺

Question 5

why does converting pryuvate to lactate allow the continued production of ATP?

Answer 5

• NAD is regenerated
• so glycolysis continues

Question 6

what must occur for glycolysis to continue?

Answer 6

• pyruvate and H must constantly be removed
• H must be released from NADH to regenerate NAD
• replenishment of NAD is achieved by pyruvate molecule from glycolysis accepting the H from reduced NADH
• oxidised NAD produced can then be used to further glycolysis

Question 7

describe anaerobic respiration in animals

Answer 7

• glucose -> pyruvate ((2 ATP released, 2 NAD -> 2NADH)
• 2 pryuvate -> 2 lactic acid (2 NAD+ -> 2 NADH)

Question 8

what happens to the lactic acid that is produced?

Answer 8

• enzyme in the liver converts lactic acid back to pyruvate
• the pryuvate can be sent to the mitochondria for the link reaction
• convertion of lactic acid -> pyruvate is an oxidation reaction
• this is called oxygen debt

Question 9

how is anaerobic respiration in animals a redox reaction?

Answer 9

• pyruvate is reduced
• 2 NADH is oxidised

Question 10

describe the summary equation for lactate production

Answer 10

pyruvate + reduced NAD ➞ lactate + oxidised NAD

Question 11

what are the 2 ways energy is derived from cellular respiration?

Answer 11

1. SLP in glycolysis and krebs
2. OP in ETC