AP BIOLOGY

Detailed explanation-1: -PFK1 is allosterically inhibited by high levels of ATP but AMP reverses the inhibitory action of ATP. Therefore, the activity of the enzyme increases when the cellular ATP/AMP ratio is lowered. Glycolysis is thus stimulated when energy charge falls.

Detailed explanation-2: -AMP activates the reaction. Thus, when energy is required, glycolysis is activated. When energy is plentiful, the reaction is slowed down.

Detailed explanation-3: -rise in AMP increases metabolism through pathways to restore energy (i.e. glycolysis, citric acid cycle etc.). Hexokinase: Catalyzes the phosphorylation of hexoses in general and is found in all cells that metabolize glucose.

Detailed explanation-4: -Because of the adenylate kinase reaction (2ADP ↔ ATP + AMP), AMP rises whenever the ATP:ADP ratio falls, and a high cellular ratio of AMP:ATP is a signal that the energy status of the cell is compromised.

Detailed explanation-5: -Activation of AMPK by AICAR in resting muscle results in increased glucose uptake [119], an effect that is lost when 2 or 3-AMPK expression is deficient [5; 85; 126]. Thus, it is logical to assume that AMPK activation during exercise is responsible for the observed increase in muscle glucose uptake (Figure 3).