anaerobic respiration

Question 1

consequences of not enough oxygen for respiration

Answer 1

1. there is no final electron acceptor in the electron transport chain
2. the electron transport chain stops functioning
3. no more atp is produced via oxidative phosphorylation
4. reduced NAD and FAD are not oxidised by an electron carrier
5. oxidised NAD and FAD are not available for dehydrogenation in krebs cycle
6. krebs cycle stops

Question 2

two pathways

Answer 2

1. ethanol fermentation
2. lactate fermentation

Question 3

ethanol fermentation

Answer 3

in this pathway reduced NAD transfers its hydrogens to ethanal to form ethanol.
in the first step of the pathway pyruvate is decarboxylated to ethanal: producing co2.
then ethanal is reduced to ethanol by the enzyme alcohol dehydrogenase.
ethanal is the hydrogen acceptor.
ethanol can not be further metabolised; it is a waste product.

Question 4

lactate fermentation

Answer 4

in this pathway reduced NAD transfers its hydrogens to pyruvate to form lactate.
pyruvate is reduced to lactate by enzyme lactate dehydrogenase.
pyruvate is the hydrogen acceptor.
the final product lactate can be further metabolised.

Question 5

metabolization of lactate

Answer 5

after lactate is produced 2 things can happen:
1. it can be oxidised back to pyruvate which is tjen chanelled into the krebs cycle for atp production.
2. it can be converted into glycogen for storage in the liver.

Question 6

oxygen debt

Answer 6

the oxidation of lactate back to pyruvate needs extra oxygen.
this extra oxygen is referred to as an oxygen debt.
it explains why animals breath deeper and faster after exercise.