CH 6 enzyme and metabolism flashcards

Q: What are the two states of energy?

A: Kinetic energy (energy of motion) and potential energy (stored energy).

Q: What is the most convenient way of measuring energy?

Heat

Q: Define oxidation in a redox reaction.

A: Loss of electrons.

Q: Define reduction in a redox reaction.

A: Gain of electrons.

Q: What does the first law of thermodynamics state?

A: Energy cannot be created or destroyed, only transformed.

Q: What does the second law of thermodynamics state?

A: Entropy (disorder) is continuously increasing in the universe.

Q: What is free energy (G)?

A: The energy available to do work.

Q: What is the equation for free energy change (ΔG)?

A: ΔG = ΔH − TΔS.

Q: What type of reaction occurs when ΔG is positive?

A: Endergonic reaction (requires energy).

Q: What type of reaction occurs when ΔG is negative?

A: Exergonic reaction (releases energy).

Q: What is activation energy?

A: The extra energy required to initiate a chemical reaction.

Q: What is a catalyst?

A: A substance that lowers the activation energy of a reaction without being consumed.

Q: What is ATP composed of?

A: Ribose (sugar), adenine (base), and three phosphates.

Q: What happens when the bonds in ATP are broken?

A: Energy is released.

Q: What is the role of ATP in cells?

A: It is the primary energy currency for short-term energy storage.

Q: What is an enzyme?

A: A biological catalyst that speeds up chemical reactions by lowering activation energy.

Q: What is the active site of an enzyme?

A: The region where substrates bind and the reaction occurs.

Q: What is an enzyme–substrate complex?

A: The intermediate formed when a substrate binds to the enzyme's active site.

Q: What factors influence enzyme activity?

A: Temperature, pH, and substrate concentration.

Q: What are competitive inhibitors?

A: Substances that compete with the substrate for the enzyme’s active site.

Q: What are noncompetitive inhibitors?

A: Substances that bind to a site other than the active site, changing the enzyme’s shape.

Q: What is the function of an allosteric enzyme?

A: It can exist in active and inactive forms and is regulated by molecules binding at the allosteric site.

Q: What are cofactors?

A: Non-protein helpers, often metal ions, that assist enzyme function.

Q: What are coenzymes?

A: Organic cofactors, often derived from vitamins, that assist enzymes.

Q: Define metabolism.

A: The total of all chemical reactions occurring in an organism.

Q: What is the difference between anabolic and catabolic reactions?

A: Anabolic reactions build molecules and consume energy; catabolic reactions break down molecules and release energy.

Q: What is feedback inhibition?

A: A regulatory mechanism where the end product of a pathway inhibits an earlier step to prevent overproduction.

Q: How do enzymes speed up reactions?

A: By lowering the activation energy required for the reaction.

Q: Why is ATP not suitable for long-term energy storage?

A: Its phosphate bonds are too unstable; fats and carbohydrates are better for long-term storage.