Q1. What’s the difference between kinetic energy and potential energy?

Background

Topic: Energy in Biological Systems

This question tests your understanding of the two main types of energy relevant to biological processes: kinetic and potential energy.

Key Terms:

• Kinetic energy: Energy of motion.

• Potential energy: Stored energy due to position or structure.

Step-by-Step Guidance

1. Recall that kinetic energy is associated with movement. Think about examples in biology, such as molecules moving across a membrane.

2. Potential energy is stored, often in chemical bonds or gradients. Consider how a molecule like glucose stores energy in its bonds.

3. Compare the two by considering how energy can be transformed from one type to another during cellular processes.

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Q2. What’s the relationship between kinetic energy and potential energy?

Background

Topic: Energy Transformations

This question explores how kinetic and potential energy are interrelated in biological systems.

Key Terms:

• Energy transformation: The process of converting one form of energy to another.

Step-by-Step Guidance

1. Think about how potential energy can be released and converted into kinetic energy, such as ATP hydrolysis powering movement.

2. Consider examples where kinetic energy is used to build up potential energy, like pumping ions to create a gradient.

3. Reflect on the principle of conservation of energy: energy is not created or destroyed, but transformed.

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Q3. Which would be considered to have more potential energy: a molecule that has a lot of O-H bonds, or a molecule that has a lot of C-H bonds? Why?

Background

Topic: Chemical Bond Energy

This question tests your understanding of how the type of chemical bond affects the amount of potential energy stored in a molecule.

Key Terms:

• C-H bond: Carbon-hydrogen bond, typically high in potential energy.

• O-H bond: Oxygen-hydrogen bond, typically lower in potential energy.

Step-by-Step Guidance

1. Recall that the energy stored in a bond depends on the electronegativity of the atoms involved.

2. Consider that C-H bonds are less polar than O-H bonds, meaning electrons are more evenly shared and thus higher in energy.

3. Think about how molecules with more C-H bonds are often used as energy sources in metabolism.

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Q4. During a chemical reaction, what does “transition state” refer to?

Background

Topic: Chemical Reactions and Activation Energy

This question is about the concept of the transition state in chemical reactions, which is crucial for understanding how enzymes work.

Key Terms:

• Transition state: The high-energy, unstable state during a reaction when old bonds are breaking and new bonds are forming.

• Activation energy: The energy required to reach the transition state.

Step-by-Step Guidance

1. Recall that the transition state is the point at which reactants are transformed into products.

2. Understand that this state is temporary and has higher energy than either reactants or products.

3. Consider how enzymes lower the activation energy needed to reach the transition state.

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Q5. What do enzymes do? What are enzymes made of? How do enzymes make it easier for a reaction to reach its transition state?

Background

Topic: Enzyme Structure and Function

This question tests your understanding of enzyme function, composition, and their role in catalyzing reactions.

Key Terms:

• Enzyme: Biological catalyst, usually a protein.

• Transition state: High-energy intermediate in a reaction.

• Activation energy: Energy required to reach the transition state.

Step-by-Step Guidance

1. Recall that enzymes speed up reactions by lowering activation energy.

2. Enzymes are typically made of proteins, though some RNA molecules can act as enzymes (ribozymes).

3. Enzymes bind substrates and stabilize the transition state, making it easier for the reaction to proceed.

4. Think about how the active site of an enzyme is specifically shaped to facilitate this process.

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Q6. What’s the relationship between enzyme, active site, and substrate?

Background

Topic: Enzyme Mechanism

This question is about how enzymes interact with substrates at their active sites to catalyze reactions.

Key Terms:

• Enzyme: Protein catalyst.

• Active site: Region on the enzyme where substrate binds.

• Substrate: The molecule upon which the enzyme acts.

Step-by-Step Guidance

1. Recall that the substrate is the molecule that the enzyme acts upon.

2. The active site is a specific region of the enzyme where the substrate binds.

3. Binding at the active site allows the enzyme to catalyze the reaction, often by stabilizing the transition state.

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Q7. What are cofactors and coenzymes? What do they do?

Background

Topic: Enzyme Regulation and Function

This question tests your understanding of molecules that assist enzymes in catalysis.

Key Terms:

• Cofactor: Non-protein molecule or ion required for enzyme activity (often metal ions).

• Coenzyme: Organic molecule that assists enzyme function (often vitamins).

Step-by-Step Guidance

1. Recall that some enzymes require additional molecules to function properly.

2. Cofactors are often inorganic ions, like Mg2+ or Fe2+.

3. Coenzymes are organic molecules, often derived from vitamins, that help transfer chemical groups or electrons.

4. Think about how these molecules help enzymes catalyze reactions by stabilizing substrates or participating in the reaction.

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Q8. Compare and contrast: Competitive inhibitor vs. Non-competitive inhibitor. What is a regulatory/allosteric site?

Background

Topic: Enzyme Regulation

This question is about how enzyme activity can be regulated by inhibitors and allosteric sites.

Key Terms:

• Competitive inhibitor: Molecule that binds to the active site, blocking substrate binding.

• Non-competitive inhibitor: Molecule that binds elsewhere (allosteric site), changing enzyme shape and reducing activity.

• Allosteric site: Regulatory site on enzyme, distinct from active site.

Step-by-Step Guidance

1. Recall that competitive inhibitors compete with the substrate for the active site.

2. Non-competitive inhibitors bind to a different site (allosteric site), causing a conformational change.

3. Think about how allosteric regulation can either inhibit or activate enzyme activity.

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Q9. What’s the difference between endergonic and exergonic reactions?

Background

Topic: Thermodynamics in Biology

This question tests your understanding of energy changes in chemical reactions.

Key Terms:

• Endergonic reaction: Requires energy input; .

• Exergonic reaction: Releases energy; .

Step-by-Step Guidance

1. Recall that is the change in free energy for a reaction.

2. Endergonic reactions absorb energy, while exergonic reactions release energy.

3. Think about examples: ATP hydrolysis is exergonic; photosynthesis is endergonic.

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Q10. What’s the general structure of ATP? What makes ATP a high energy molecule?

Background

Topic: ATP Structure and Function

This question is about the molecular structure of ATP and why it is considered high energy.

Key Terms:

• ATP: Adenosine triphosphate, the cell's energy currency.

• Phosphate groups: Linked by high-energy bonds.

Step-by-Step Guidance

1. Recall that ATP consists of adenine, ribose, and three phosphate groups.

2. The bonds between the phosphate groups are high energy due to repulsion between negative charges.

3. When ATP is hydrolyzed, energy is released for cellular work.

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Q11. How is ATP used to make proteins inside cells move (change shape)?

Background

Topic: ATP and Cellular Movement

This question is about how ATP powers movement and shape changes in proteins, such as motor proteins.

Key Terms:

• ATP hydrolysis: Breaking down ATP to ADP and Pi, releasing energy.

• Motor proteins: Proteins that move along cytoskeletal filaments.

Step-by-Step Guidance

1. Recall that ATP hydrolysis releases energy.

2. Motor proteins (like myosin, kinesin) use this energy to change shape and move.

3. Think about how conformational changes in proteins are driven by ATP binding and hydrolysis.

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Q12. What is a phosphorylation reaction?

Background

Topic: Phosphorylation in Cell Biology

This question is about the process of adding a phosphate group to a molecule, which is important in signaling and metabolism.

Key Terms:

• Phosphorylation: Addition of a phosphate group to a molecule.

• Kinase: Enzyme that catalyzes phosphorylation.

Step-by-Step Guidance

1. Recall that phosphorylation involves transferring a phosphate group, often from ATP, to another molecule.

2. This process is catalyzed by kinases.

3. Phosphorylation can activate or deactivate proteins, or change their function.

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