Questions and Answers
Which reactions release energy?
Which reactions consume energy?
What type of reaction is photosynthesis?
What type of reaction is cellular respiration?
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Contrast kinetic energy with potential energy.
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Which type of energy does water behind a dam have?
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What is free energy and what is its symbol?
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The equation for the change in free energy is ∆G = __________.
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For an exergonic reaction, is ∆G negative or positive?
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Is cellular respiration an endergonic or exergonic reaction?
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Is photosynthesis endergonic or exergonic?
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What is energy coupling?
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What is a catalyst?
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What is activation energy (Ea)?
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What is meant by induced fit?
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Explain how temperature can affect the rate of enzyme action.
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Name a human enzyme that functions well at pH 2. Where is it formed?
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Distinguish between cofactors and coenzymes. Give examples of each.
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What is allosteric regulation?
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Study Notes
Metabolism Reactions
- Catabolic reactions release energy by breaking down larger molecules.
- Anabolic reactions consume energy to build up larger molecules.
- Photosynthesis is an anabolic reaction; it requires energy to synthesize glucose.
- Cellular respiration is a catabolic reaction that releases energy.
Energy Concepts
- Kinetic energy is the energy of motion; potential energy is stored due to an object's position or structure.
- Water behind a dam and a mole of glucose both possess potential energy.
Free Energy
- Free energy (symbol: G) indicates the portion of energy in a system that can perform work under uniform conditions.
- Change in free energy is represented by the equation: ∆G = ∆H - T∆S.
- In exergonic reactions, ∆G is negative; for cellular respiration, it is -686 kcal/mol.
Cellular Work Types
- Cells perform three main types of work:
- Chemical work: synthesizing polymers from monomers.
- Transport work: moving substances across membranes against their gradient.
- Mechanical work: activities like cilia beating and muscle contraction.
ATP and Energy Release
- The hydrolysis of ATP (ATP → ADP + Pi) releases -7.3 kcal/mol of energy, categorized as an exergonic reaction.
- Energy coupling refers to using the energy from exergonic processes to drive endergonic reactions.
Enzymatic Action
- Catalysts speed up reactions without being consumed.
- Activation energy (Ea) is the energy required to initiate a chemical reaction.
- Induced fit describes how enzymes adjust their shape to better catalyze reactions.
- Enzyme specificity is influenced by protein structure.
Factors Affecting Enzymes
- The rate of enzyme action can be affected by substrate concentration; more substrate can lead to increased reaction rates until saturation.
- Extreme pH levels and temperatures can denature enzymes, rendering them inactive.
- Pepsin, a digestive enzyme, functions at a pH of 2, found in the stomach.
Cofactors and Inhibitors
- Cofactors are inorganic, while coenzymes are organic; examples include zinc for cofactors and vitamins for coenzymes.
- Competitive inhibitors block substrates from binding to the active site, while noncompetitive inhibitors bind at a different site, altering enzyme shape and function.
Allosteric Regulation
- Allosteric regulation modifies enzyme activity, with regulatory molecules binding at sites other than the active site.
- Allosteric activators enhance enzyme activity, whereas allosteric inhibitors decrease it.
- Hemoglobin demonstrates cooperativity in O₂ binding, enhancing its efficiency in oxygen transport, particularly in the gills of fish.
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Description
Explore the fundamental concepts of metabolism with these flashcards from AP Biology Chapter 8. Learn about catabolic and anabolic reactions, their functions, and their relevance in biological processes such as photosynthesis. Perfect for students preparing for exams in biology.