Anaerobic Respiration In Plants/fungi/yeast

Question 1

What are the steps of anaerobic respiration in plants/fungi/yeast?

Answer 1

• Ethanol fermentation
• In this pathway,reduced NAD transfers its hydrogen to ethanal to form ethanol
• the pathway pyruvate is carboxylated to ethanal
• produced carbon dioxide
• The ethanal is reduced to ethanol by the enzyme alcohol dehydrogenase
• Ethanal is the hydrogen acceptor
• Ethanol cannot be further metabolised, it is a waste product

Question 2

What happens when each pyruvate molecule loses a carbon dioxide?

Answer 2

• It forms ethanal
• it is catalysed by the enzyme pyruvate decarboxylase (which has a co-enzyme attached to it)
• ethanal then accepts the hydrogen atom to form the reduced NAD (which is re-oxidised) and the ethanal is reduced to ethanol using the enzyme ethanol dehydrogenase

Question 3

What does it mean by yest is a facultative anaerobe?

Answer 3

• It can live without oxygen
• However, if it continues for too long, it will die as the concentration for too long, it will die as the concentration of ethanol builds up (once it reaches 15%)

Question 4

What happens during the brewing process?

Answer 4

• Yeast is grown under aerobic conditions at first, then switches to anaerobic conditions for alcoholic fermentation to occur.