Pyruvate Dehydrogenase: Covalent Regulation

The video explains the covalent regulation of the pyruvate dehydrogenase complex, a key enzyme linking glycolysis and the TCA cycle. It discusses how pyruvate is converted to acetyl CoA, the importance of regulating this enzyme due to its role in various metabolic pathways, and the mechanisms of covalent regulation through phosphorylation. The video also covers higher-level regulation involving allosteric control by molecules like ATP and NADH, and the role of calcium in activating the enzyme.

What is the primary role of the pyruvate dehydrogenase complex?

• To convert ATP to ADP

• To convert glucose to pyruvate

• To convert pyruvate to acetyl CoA

• To convert acetyl CoA to pyruvate

Why is it important to regulate the pyruvate dehydrogenase complex?

• Because glycolysis does not produce pyruvate

• Because pyruvate is not a significant source of energy

• Because acetyl CoA has multiple fates, including lipid biosynthesis

• Because acetyl CoA is only used in the TCA cycle

What happens to pyruvate dehydrogenase when it is phosphorylated?

• It converts acetyl CoA to pyruvate

• It becomes inactive

• It becomes active

• It starts glycolysis

Which enzyme is responsible for reactivating pyruvate dehydrogenase by removing a phosphate group?

• PDH kinase

• PDH phosphatase

• Citrate synthase

• Alpha-ketoglutarate dehydrogenase

What effect do high levels of ATP have on pyruvate dehydrogenase?

• They activate pyruvate dehydrogenase

• They inhibit pyruvate dehydrogenase

• They have no effect on pyruvate dehydrogenase

• They convert pyruvate to glucose

How do high levels of calcium affect pyruvate dehydrogenase phosphatase?

• They activate the phosphatase

• They convert acetyl CoA to pyruvate

• They have no effect on the phosphatase

• They inhibit the phosphatase

Which of the following molecules allosterically activates PDH kinase?

• NADH

• Calcium

• Glucose

• ADP