AP BIOLOGY

Detailed explanation-1: -High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of Select one: O a. the specificity of enzymes for their substrates.

Detailed explanation-2: -High levels of citric acid inhibit glycolysis rate. Step one of the citric acid cycle is controlled by negative feedback and the amount of ATP available. If ATP levels increase, the rate of this reaction decreases. If ATP is in short supply, the rate increases.

Detailed explanation-3: -In glycolysis, phosphofructokinase (PFK) is a key regulator of the overall reactions. It exists as a tetramer and each subunit has two binding sites for ATP. This enzyme catalyzes the first unique step in glycolysis, converting fructose-6-phosphate to fructose-1, 6-bisphosphate.

Detailed explanation-4: -Citrate. Citrate, the first product of the citric acid cycle, can also inhibit PFK. If citrate builds up, this is a sign that glycolysis can slow down, because the citric acid cycle is backed up and doesn’t need more fuel.

Detailed explanation-5: -Allosteric inhibitors modify the active site of the enzyme so that substrate binding is reduced or prevented. In contrast, allosteric activators modify the active site of the enzyme so that the affinity for the substrate increases.