33 Questions
What is the key difference between anabolic and catabolic reactions?
Anabolic reactions synthesize molecules with more bonds
Which concept describes the chemical energy available to do work?
Free energy (G)
What does a negative ∆G value for a reaction indicate?
The reaction is exergonic
Which term refers to the network of anabolic and catabolic reactions in a cell?
Metabolism
Why do enzymes reduce the activation energy of a reaction?
To speed up the reaction rate
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.
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.
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 $\Delta G$.
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.
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.
Which of the following statements accurately describes the first law of thermodynamics?
Energy can be neither created nor destroyed, but can be transformed.
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.
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.
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.
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.
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
In a negative feedback loop in metabolic pathways, what inhibits an enzyme at the beginning of a pathway?
Product of the pathway
Which energy carrier captures high-energy electrons from organic molecules in metabolism?
NADH
What is the primary function of NADH (or NADPH) in cellular processes?
Act as an electron carrier
In reaction coupling, how are positive ∆G reactions made to work in living cells?
Through hydrolysis of ATP
Which reaction is used to accomplish positive ∆G reactions through reaction coupling?
$ADP + Pi \rightleftharpoons ATP$
What type of reaction combines a positive ∆G reaction with a negative ∆G reaction to yield a net negative ∆G?
$ADP + Pi \rightleftharpoons ATP$
What is the primary function of enzymes in negative ∆G reactions?
- Decrease energy required for the reaction
$NAD^+$ is reduced to $NADH$ during which process?
$Reduction$
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.
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.
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.
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.
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.
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 $\Delta G$.
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.
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.
Which term refers to the overall network of anabolic and catabolic reactions that make up a cell's metabolism?
Metabolic pathways
Learn about the concept of metabolism, which involves anabolic reactions that build molecules with more bonds and store energy, as well as catabolic reactions that degrade molecules to release energy. Understand how these reactions are interconnected in cellular pathways.
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