Metabolism: Anabolic and Catabolic Reactions

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What is the key difference between anabolic and catabolic reactions?

Anabolic reactions release energy

Anabolic reactions decrease entropy

Anabolic reactions are spontaneous

Anabolic reactions synthesize molecules with more bonds (correct)

Which concept describes the chemical energy available to do work?

Free energy (G) (correct)

Activation energy

Entropy

Enthalpy

What does a negative ∆G value for a reaction indicate?

The reaction is non-spontaneous

The reaction has high entropy

The reaction is exergonic (correct)

The reaction requires energy

Which term refers to the network of anabolic and catabolic reactions in a cell?

Metabolism (C) Signup and view all the answers

Why do enzymes reduce the activation energy of a reaction?

To speed up the reaction rate (D) Signup and view all the answers

Which of the following statements about allosteric regulation of enzymes is correct?

Allosteric effectors bind to a site other than the active site and alter the enzyme's shape to regulate its activity. (C) Signup and view all the answers

Which of the following statements accurately describes negative feedback regulation in metabolic pathways?

The product of a pathway inhibits an enzyme at the beginning of the pathway. (D) Signup and view all the answers

What is the primary mechanism by which positive $\Delta G$ reactions are accomplished in cells?

By coupling them with negative $\Delta G$ reactions to yield a net negative $\Delta G$. (A) Signup and view all the answers

Which of the following statements about ATP is correct in the context of reaction coupling?

ATP hydrolysis is the most common means of reaction coupling to generate phosphorylated intermediates. (A) Signup and view all the answers

Which of the following statements accurately describes the role of NADH (or NADPH) in metabolism?

NADH (or NADPH) is a high-energy electron carrier that captures electrons from organic molecules for later energy extraction. (A) Signup and view all the answers

Which of the following statements accurately describes the first law of thermodynamics?

Energy can be neither created nor destroyed, but can be transformed. (C) Signup and view all the answers

Which of the following statements accurately describes the relationship between enthalpy, entropy, and free energy in reactions?

Enthalpy is the total energy of a system, entropy is a measure of disorder, and free energy is the energy available to do work. (C) Signup and view all the answers

Which of the following statements accurately compares anabolic and catabolic reactions in terms of free energy change?

Anabolic reactions have a positive $\Delta G$ and are endergonic, while catabolic reactions have a negative $\Delta G$ and are exergonic. (C) Signup and view all the answers

Which of the following statements accurately describes the role of enzymes in negative $\Delta G$ reactions?

Enzymes lower the activation energy barrier for negative $\Delta G$ reactions, allowing them to proceed more rapidly. (B) Signup and view all the answers

Which of the following statements accurately describes the process of oxidation and reduction in the context of electron transfer?

Oxidation is the loss of electrons, and reduction is the gain of electrons. (D) Signup and view all the answers

What is the primary role of allosteric effectors in enzyme regulation?

Bind at a different site to alter the protein's shape and regulate enzyme activity (A) Signup and view all the answers

In a negative feedback loop in metabolic pathways, what inhibits an enzyme at the beginning of a pathway?

Product of the pathway (D) Signup and view all the answers

Which energy carrier captures high-energy electrons from organic molecules in metabolism?

NADH (B) Signup and view all the answers

What is the primary function of NADH (or NADPH) in cellular processes?

Act as an electron carrier (D) Signup and view all the answers

In reaction coupling, how are positive ∆G reactions made to work in living cells?

Through hydrolysis of ATP (B) Signup and view all the answers

Which reaction is used to accomplish positive ∆G reactions through reaction coupling?

$ADP + Pi \rightleftharpoons ATP$ (B) Signup and view all the answers

What type of reaction combines a positive ∆G reaction with a negative ∆G reaction to yield a net negative ∆G?

$ADP + Pi \rightleftharpoons ATP$ (A) Signup and view all the answers

What is the primary function of enzymes in negative ∆G reactions?

<ul> <li>Decrease energy required for the reaction (C)</li> </ul> Signup and view all the answers

$NAD^+$ is reduced to $NADH$ during which process?

$Reduction$ (D) Signup and view all the answers

Which of the following best describes the relationship between anabolic and catabolic reactions in a cell's metabolism?

Anabolic and catabolic reactions are connected in a network of reaction pathways that make up the cell's overall metabolism. (B) Signup and view all the answers

According to the Second Law of Thermodynamics, which of the following statements is true about the relationship between energy and entropy in chemical reactions?

Energy is transformed in many ways, but some energy is always lost through an increase in entropy. (D) Signup and view all the answers

What is the relationship between $\Delta G$, enthalpy, and entropy in chemical reactions?

Free energy ($\Delta G$) is the difference between enthalpy and entropy, and it determines the spontaneity of a reaction. (A) Signup and view all the answers

How do enzymes influence the activation energy of a chemical reaction?

Enzymes reduce the activation energy of a reaction, making it more likely to occur. (D) Signup and view all the answers

Which of the following best describes the mechanism by which enzymes interact with their substrates?

Enzymes and substrates form an enzyme-substrate complex through induced fit, which optimizes their interaction. (B) Signup and view all the answers

What is the primary function of ATP in the context of metabolic reactions?

ATP provides the energy required to drive anabolic reactions that have a positive $\Delta G$. (C) Signup and view all the answers

How do negative feedback mechanisms regulate metabolic pathways?

Negative feedback inhibits the activity of enzymes in a pathway when the final product is in excess, reducing the rate of the pathway. (B) Signup and view all the answers

What is the role of NADH (or NADPH) in cellular metabolism?

NADH and NADPH are high-energy electron carriers that provide the reducing power required for anabolic reactions. (A) Signup and view all the answers

Which term refers to the overall network of anabolic and catabolic reactions that make up a cell's metabolism?

Metabolic pathways (C) Signup and view all the answers