Question

high levels of pyruvate: group of answer choices inhibit pyruvate dehydrogenase kinase and therefore increase the activity of the pyruvate dehydrogenase complex. activate pyruvate dehydrogenase phosphatase and hence inhibit the activity of pyruvate dehydrogenase complex. activate pyruvate dehydrogenase kinase and consequently activate the pyruvate dehydrogenase complex. activate pyruvate dehydrogenase phosphatase and therefore promote phosphorylation of the pyruvate dehydrogenase complex. inhibit pyruvate dehydrogenase phosphatase and therefore enhance the activity of pyruvate dehydrogenase complex.

Answer 1

High levels of pyruvate inhibit pyruvate dehydrogenase kinase and activate pyruvate dehydrogenase phosphatase, leading to an increase in the activity of the pyruvate dehydrogenase complex, which is essential for ATP production during high energy demands.

Step-by-step explanation:

High levels of pyruvate lead to an increase in the activity of the pyruvate dehydrogenase complex. This occurs because the accumulated pyruvate inhibits pyruvate dehydrogenase kinase, which is responsible for phosphorylating and inactivating the complex. Conversely, high levels of pyruvate activate pyruvate dehydrogenase phosphatase, which causes dephosphorylation of the pyruvate dehydrogenase complex, thereby activating it. These regulatory mechanisms are crucial for cellular energy production, as the conversion of pyruvate into acetyl CoA by the pyruvate dehydrogenase complex is an important step in the cellular respiration process, including the Citric Acid Cycle. Hence, when energy demands are high, the regulation of these enzymes ensures that more pyruvate is funneled into the Citric Acid Cycle for ATP production.

Answer 2

The correct option from the given choices would be: activate pyruvate dehydrogenase kinase and therefore increase the activity of the pyruvate dehydrogenase complex.

High levels of pyruvate would typically activate pyruvate dehydrogenase kinase (PDK) and consequently inhibit the pyruvate dehydrogenase complex (PDC).

Option A (correct): Activating pyruvate dehydrogenase kinase (PDK) inhibits the pyruvate dehydrogenase complex (PDC) by phosphorylating it. This is a regulatory mechanism to slow down the conversion of pyruvate to acetyl-CoA when there is an excess of pyruvate.

In summary, high pyruvate levels activate PDK, which inhibits the PDC, and this helps to regulate the metabolic pathway and maintain cellular homeostasis.