Cellular Energy Flow, Metabolism, and Enzyme Regulation

All flashcards

What is a metabolic pathway?

An ordered series of enzyme-catalyzed reactions that modifies a starting molecule through intermediates into a final product.

How do ATP and glucose differ in cellular energy use?

ATP transfers energy for immediate cellular work; glucose is a molecule that stores energy cells can transfer to ATP.

What does the induced-fit model describe?

Substrate binding causes a slight enzyme shape change that improves binding and helps catalysis.

How do competitive and noncompetitive inhibitors differ?

Competitive inhibitors bind at the active site; noncompetitive inhibitors bind elsewhere and reduce enzyme activity.

What is feedback inhibition?

A pathway product inhibits an enzyme involved in making that product, slowing further production.

Quiz questions

1. An organism takes in energy and releases some energy to its surroundings as heat. What type of system is it?Answer: An open system that exchanges energy with its surroundings.
2. What does the first law of thermodynamics state about energy?Answer: Energy cannot be created or destroyed, but it can be transferred or transformed.
3. For a reaction with positive $\Delta G$, which description is correct?Answer: It is endergonic and requires net free-energy input unless coupled to an energy source.
4. How do enzymes affect a reaction's energetics?Answer: They lower activation energy without changing the reaction's overall $\Delta G$.
5. Which statement distinguishes a coenzyme from a cofactor?Answer: A coenzyme is an organic helper molecule; a cofactor is an inorganic helper, such as an ion.