What does a competitive inhibitor do?

• Binds the active site, raising substrate need without changing the maximum rate
• Destroys the enzyme permanently at any dose
• Adds extra ATP to the reaction

What is metabolic flux?

• The temperature of the cell
• The number of genes for one enzyme
• The rate at which material flows through a pathway

Calling a single enzyme the rate-limiting step is usually an approximation.

Circle one:   True   False

Two proposed routes send a labelled atom to different products. The label appears in product B. What follows?

• Both routes run equally
• The label proves nothing
• The route leading to product B is the one used

Doubling one enzyme barely changes pathway flow. What does that show?

• The enzyme is completely broken
• Control is shared with other steps
• The pathway runs backward

How do you predict where a label ends up on a proposed route?

• Follow the atom through each reaction to its product position
• Count the total atoms in the cell
• Measure the cell temperature first

Studying all regulated points of respiration together beats crowning one valve, because control is distributed.

Circle one:   True   False

A student finds an inhibitor that lowers the maximum rate and calls it competitive. What is wrong?

• Inhibitors never bind enzymes
• Competitive inhibition leaves the maximum rate unchanged
• Maximum rate cannot be measured