Exam 8: An Introduction to Metabolism

A series of enzymes catalyse the reactions in the metabolic pathway X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme. What is substance X?

Which of the following statements about enzyme function is true?

How do cells use the ATP cycle illustrated in the figure?

Which of the following conditions may be overcome by increasing the substrate concentration in an enzymatic reaction with a fixed amount of enzyme?

Some bacteria are metabolically active in hot springs because

Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localisation?

In a metabolic pathway, succinate dehydrogenase catalyses the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect of malonic acid. What role does malonic acid play with respect to succinate dehydrogenase?