Q1. What is anabolism?

Background

Topic: Metabolism – Anabolism

This question tests your understanding of the two main types of metabolic pathways: anabolism and catabolism. Anabolism refers to the set of metabolic pathways that construct molecules from smaller units.

Key Terms:

• Anabolism: The biosynthetic phase of metabolism, where smaller molecules are built up into larger, more complex molecules.

Step-by-Step Guidance

1. Recall that metabolism is divided into two main categories: anabolism and catabolism.

2. Think about the processes in the body that require energy input to build complex molecules (e.g., protein synthesis, DNA replication).

3. Consider the role of ATP in providing energy for these biosynthetic reactions.

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Q2. What is catabolism?

Background

Topic: Metabolism – Catabolism

This question is about the breakdown phase of metabolism, where larger molecules are degraded into smaller ones, releasing energy.

Key Terms:

• Catabolism: The degradative phase of metabolism, where complex molecules are broken down into simpler ones, releasing energy.

Step-by-Step Guidance

1. Recall that catabolism is the opposite of anabolism.

2. Think about examples of catabolic processes (e.g., glycolysis, fatty acid oxidation).

3. Consider how catabolic reactions release energy, often captured in the form of ATP or reduced coenzymes (NADH, FADH2).

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Q3. Why is ATP such a high energy molecule?

Background

Topic: ATP Structure and Function

This question tests your understanding of why ATP (adenosine triphosphate) is considered the energy currency of the cell.

Key Terms and Concepts:

• ATP: Adenosine triphosphate, a molecule that stores and transfers energy in cells.

• Phosphoanhydride bonds: The bonds between phosphate groups in ATP, which are high-energy bonds.

Step-by-Step Guidance

1. Recall the structure of ATP: adenine, ribose, and three phosphate groups.

2. Think about the repulsion between the negatively charged phosphate groups.

3. Consider what happens when ATP is hydrolyzed to ADP and inorganic phosphate (Pi).

4. Reflect on how the energy released from breaking these bonds is used in cellular processes.

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Q4. Write the overall equation for the combined reaction of glucose phosphorylation and ATP hydrolysis including the net energy change.

Background

Topic: Coupled Reactions in Metabolism

This question tests your ability to combine two biochemical reactions and calculate the net energy change.

Key Terms and Formulas:

• Glucose phosphorylation:

• ATP hydrolysis:

• Net reaction: Add the two reactions and sum the energy changes.

Step-by-Step Guidance

1. Write the equation for glucose phosphorylation and note the energy required (+3.3 kcal/mol).

2. Write the equation for ATP hydrolysis and note the energy released (−7.3 kcal/mol).

3. Add the two reactions, canceling out Pi as an intermediate.

4. Sum the energy changes to find the net energy change for the coupled reaction.

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Q5. What does the structure of NAD+ look like? What types of reactions can NAD+ participate in?

Background

Topic: Coenzymes in Metabolism

This question is about the structure and function of NAD+ (nicotinamide adenine dinucleotide), a key electron carrier in metabolism.

Key Terms:

• NAD+: An oxidized coenzyme that accepts electrons during redox reactions.

• Redox reactions: Reactions involving the transfer of electrons.

Step-by-Step Guidance

1. Recall that NAD+ consists of two nucleotides joined through their phosphate groups: one with an adenine base, the other with nicotinamide.

2. Think about the role of NAD+ in accepting electrons (as a hydride ion, H−) during oxidation reactions.

3. Consider the types of metabolic pathways where NAD+ is reduced to NADH (e.g., glycolysis, TCA cycle).

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Q6. What vitamin is a precursor for NAD+?

Background

Topic: Vitamins as Coenzyme Precursors

This question tests your knowledge of the vitamins required for coenzyme synthesis.

Key Term:

• Niacin (Vitamin B3): The vitamin precursor for NAD+.

Step-by-Step Guidance

1. Recall which B vitamin is converted into NAD+ in the body.

2. Think about dietary sources of this vitamin and its importance in metabolism.

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Q7. Is NAD+ in an oxidized or reduced state? What is the formula for NAD+ after a redox reaction?

Background

Topic: Redox States of Coenzymes

This question is about recognizing the oxidized and reduced forms of NAD+ and their roles in metabolism.

Key Terms:

• Oxidized state: NAD+

• Reduced state: NADH

Step-by-Step Guidance

1. Recall that NAD+ is the oxidized form and accepts electrons to become NADH.

2. Write the redox reaction:

3. Identify the formula for the reduced form after the reaction.

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Q8. What does the structure of FAD look like? What types of reactions can FAD participate in?

Background

Topic: Coenzymes in Metabolism

This question is about the structure and function of FAD (flavin adenine dinucleotide), another important electron carrier.

Key Terms:

• FAD: A coenzyme involved in redox reactions, especially in the citric acid cycle and electron transport chain.

Step-by-Step Guidance

1. Recall that FAD consists of a riboflavin (vitamin B2) moiety linked to an adenine nucleotide.

2. Think about the types of reactions FAD participates in (e.g., dehydrogenation reactions).

3. Consider where FAD is reduced to FADH2 in metabolism.

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Q9. What vitamin is a precursor for FAD?

Background

Topic: Vitamins as Coenzyme Precursors

This question tests your knowledge of the vitamin required for FAD synthesis.

Key Term:

• Riboflavin (Vitamin B2): The vitamin precursor for FAD.

Step-by-Step Guidance

1. Recall which B vitamin is converted into FAD in the body.

2. Think about the importance of this vitamin in energy metabolism.

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Q10. Is FAD in an oxidized or reduced state? What is the formula for FAD after a redox reaction?

Background

Topic: Redox States of Coenzymes

This question is about recognizing the oxidized and reduced forms of FAD and their roles in metabolism.

Key Terms:

• Oxidized state: FAD

• Reduced state: FADH2

Step-by-Step Guidance

1. Recall that FAD is the oxidized form and accepts two electrons and two protons to become FADH2.

2. Write the redox reaction:

3. Identify the formula for the reduced form after the reaction.

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Q11. Label each step of glycolysis with the type of reaction that is taking place.

Background

Topic: Glycolysis – Reaction Types

This question asks you to identify the type of chemical reaction occurring at each step of glycolysis. Understanding these helps you see how glucose is converted to pyruvate.

Key Terms:

• Phosphorylation: Addition of a phosphate group.

• Isomerization: Rearrangement of atoms within a molecule.

• Cleavage: Splitting of a molecule into two smaller molecules.

• Dehydrogenation: Removal of hydrogen atoms (oxidation).

• Substrate-level phosphorylation: Direct transfer of a phosphate group to ADP to form ATP.

Step-by-Step Guidance

1. Review the glycolysis pathway and identify the enzyme for each step.

2. For each step, determine if it is a phosphorylation, isomerization, cleavage, oxidation, or substrate-level phosphorylation.

3. Use the provided diagram to match each reaction with its type.

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Q12. Label each step of the last 5 reactions in glycolysis with the type of reaction that is taking place.

Background

Topic: Glycolysis – Energy-Generating Reactions

This question focuses on the second half of glycolysis, where ATP and NADH are produced.

Key Terms:

• Oxidation: Loss of electrons (often as hydrogen atoms).

• Phosphorylation: Addition of a phosphate group.

• Dehydration: Removal of water.

• Substrate-level phosphorylation: Direct formation of ATP from ADP and a phosphorylated substrate.

Step-by-Step Guidance

1. Review the last five steps of glycolysis using the provided diagram.

2. Identify the enzyme and reaction type for each step (e.g., oxidation, phosphorylation, dehydration, substrate-level phosphorylation).

3. Label each step accordingly.

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Q13. Label each step of the citric acid cycle with the type of reaction that is taking place.

Background

Topic: Citric Acid Cycle – Reaction Types

This question asks you to identify the type of chemical reaction at each step of the citric acid cycle (Krebs cycle).

Key Terms:

• Condensation: Joining of two molecules with the loss of a small molecule (often water).

• Isomerization: Rearrangement of atoms within a molecule.

• Oxidative decarboxylation: Removal of a carboxyl group as CO2 with oxidation.

• Substrate-level phosphorylation: Formation of GTP or ATP from GDP or ADP.

• Hydration: Addition of water.

Step-by-Step Guidance

1. Review the citric acid cycle diagram and identify the enzyme for each step.

2. For each step, determine if it is a condensation, isomerization, oxidative decarboxylation, substrate-level phosphorylation, or hydration reaction.

3. Label each step accordingly using the diagram.

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Q14. Label the ketogenic and glucogenic amino acids.

Background

Topic: Amino Acid Metabolism

This question is about classifying amino acids based on whether their carbon skeletons can be converted to glucose (glucogenic) or ketone bodies (ketogenic).

Key Terms:

• Glucogenic amino acids: Amino acids whose carbon skeletons can be converted to glucose via gluconeogenesis.

• Ketogenic amino acids: Amino acids whose carbon skeletons are converted to acetyl-CoA or acetoacetate, leading to ketone body formation.

Step-by-Step Guidance

1. Review the metabolic fates of amino acids using the provided diagram.

2. Identify which amino acids are exclusively glucogenic, exclusively ketogenic, or both.

3. Label each amino acid accordingly on the diagram.

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