Anaerobic Respiration

Question 1

What happens if there is not enough oxygen for respiration?

Answer 1

• Anaerobic respiration occurs
• No final electron acceptor
• Electron transport chain doesn’t work
• So no ATP produced via oxidative phosphorylation
• No FADH2 or NADH oxidised
• Kreb’s cycle stops

Question 2

How does Ethanol Fermentation work?

Answer 2

• Yeast and microbes use this
• Pyruvate decarboxylated to ethanal (pyruvate decarboxylase)
• Ethanal reduced to ethanol H+ accepted from NADH (ethanol dehydrogenase)
• NADH oxidised to NAD so glycolysis can continue (where 2 ATP molecules are produced per glucose)
• Ethanol cannot be further metabolised so is a waste product

Question 3

How does Lactate Fermentation Work?

Answer 3

• NADH transfers H to pyruvate reducing it to lactate
• Lactate dehydrogenase catalyses
• Lactate gets metabolised
• Either oxidised back to pyruvate, then channeled to Kreb’s cycle for ATP production (requires oxygen (creating oxygen debt))
• Or converted to glycogen for storage in liver