mod 4 Anaerobic Metabolism

Pyruvate is the branch point for aerobic and anaerobic catabolism of glucose. (diagram)

Glycolysis can function to create pyruvate under both anaerobic and aerobic conditions, but what happens to pyruvate next depends on the presence or lack of oxygen. Under aerobic conditions, pyruvate is converted to acetyl-CoA and continues to the citric acid cycle and cellular respiration. Under anaerobic conditions, pyruvate is converted to lactate via fermentation, and enters the Cori cycle. If the cell has plenty of ATP, pyruvate will be converted back to glucose for storage as glycogen.

The formation of lactate regenerates the

NAD+ that was used during glycolysis, thus allowing glycolysis to continue making small amounts of ATP for the cell.

anaerobic

Process that does not require oxygen

Gluconeogenesis

formation of glucose from noncarbohydrate sources a reaction that iss essentially the opposite of glycolysis Gluconeogenesis takes excess pyruvate and converts it back into glucose for transport or storage.

RBCs must rely on _________ as their sole pathway for producing ATP.

glycolysis because they lack a mitochondria and therefore the citric acid cycle and the electron transport chain

Fermentation

pyruvate is reduced via an anaerobic pathway by the addition of two hydrogen atoms to form lactic acid (lactate).

What does the liver cell do

take up the lactate from the blood and use the gluconeogenesis pathway to convert two molecules of lactate back to glucose

This anaerobic production of ATP is important to ensuring

that the oxygen bound to hemoglobin in the RBC is not consumed before it is delivered to the tissues.

In the Cori cycle, lactate produced by fermentation leaves

the cell and enters the blood.

Some of the lactate produced as a result of fermentation can be converted back to pyruvate and enter cellular respiration. However, this process can only happen when

the cell is no longer anaerobic, and it cannot happen in RBCs, which lack mitochondria

how many molecules are needed for gluconeogenesis to occur

6 molecules of ATP only 2 are produced by glycolysis

under anaerobic conditions in most cells, or continually in RBCs, the lactate is eventually converted back to glucose in a process known as the

Cori cycle