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Questions and Answers
Which of these options is correct regarding enzymes?
Which of these options is correct regarding enzymes?
- Enzymes speed up the rate of the reaction without changing the ΔG for the reaction. (correct)
- All of the listed responses are correct.
- Enzymes are consumed during the reaction.
- Enzymes decrease the reaction rate.
What is the most reasonable explanation for the low velocity of an enzyme at 10°C?
What is the most reasonable explanation for the low velocity of an enzyme at 10°C?
- There is too little activation energy available. (correct)
- The substrate becomes a competitive inhibitor at lower temperature.
- The enzyme was denatured.
- The hydrogen bonds that define the structure of the enzyme's active site are unstable.
- The cofactors required by the enzyme system lack the thermal energy required to activate the enzyme.
Which of the following statements about enzymes is incorrect?
Which of the following statements about enzymes is incorrect?
- An enzyme is consumed during the reaction it catalyzes. (correct)
- An enzyme is very specific in terms of which substrate it binds to.
- Enzymes can be used to accelerate both anabolic and catabolic reactions.
- An enzyme lowers the activation energy of a chemical reaction.
- Most enzymes are proteins.
Which of the following statements about the active site of an enzyme is correct?
Which of the following statements about the active site of an enzyme is correct?
What does the term 'induced fit' of an enzyme mean?
What does the term 'induced fit' of an enzyme mean?
Which statements correctly describe the roles of heat in biological reactions?
Which statements correctly describe the roles of heat in biological reactions?
Above a certain substrate concentration, the rate of an enzyme-catalyzed reaction drops as the enzymes become saturated. What would lead to a faster conversion of substrate into product under these conditions?
Above a certain substrate concentration, the rate of an enzyme-catalyzed reaction drops as the enzymes become saturated. What would lead to a faster conversion of substrate into product under these conditions?
Which of the following environments or actions would not affect the rate of an enzyme reaction?
Which of the following environments or actions would not affect the rate of an enzyme reaction?
Enzyme activity is affected by pH because _____
Enzyme activity is affected by pH because _____
Which of these statements about enzyme inhibitors is true?
Which of these statements about enzyme inhibitors is true?
What best explains the observation that succinylcholine decreases the rate of acetylcholine hydrolysis?
What best explains the observation that succinylcholine decreases the rate of acetylcholine hydrolysis?
The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of _____
The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule is an example of _____
Which of the following statements about allosteric proteins is/are true?
Which of the following statements about allosteric proteins is/are true?
The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. What best explains why this decrease occurs?
The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. What best explains why this decrease occurs?
Under most conditions, the supply of energy by catabolic pathways is regulated by the demand for energy by anabolic pathways. Considering the role of ATP formation and hydrolysis in energy coupling, which of the following statements is most likely to be true?
Under most conditions, the supply of energy by catabolic pathways is regulated by the demand for energy by anabolic pathways. Considering the role of ATP formation and hydrolysis in energy coupling, which of the following statements is most likely to be true?
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______.
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _______ is to _______.
Most cells cannot harness heat to perform work because:
Most cells cannot harness heat to perform work because:
Which of the following metabolic processes can occur without a net influx of energy from some other process?
Which of the following metabolic processes can occur without a net influx of energy from some other process?
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to:
If an enzyme in solution is saturated with substrate, the most effective way to obtain a faster yield of products is to:
Some bacteria are metabolically active in hot springs because:
Some bacteria are metabolically active in hot springs because:
If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?
If an enzyme is added to a solution where its substrate and product are in equilibrium, what will occur?
Which of the following correctly states the relationship between anabolic and catabolic pathways?
Which of the following correctly states the relationship between anabolic and catabolic pathways?
Which of the following situations does not represent an energy transformation?
Which of the following situations does not represent an energy transformation?
Organisms are described as thermodynamically open systems. Which of the following statements is consistent with this description?
Organisms are described as thermodynamically open systems. Which of the following statements is consistent with this description?
Consider the growth of a farmer's crop over a season. Which of the following correctly states a limitation imposed by the first or second law of thermodynamics?
Consider the growth of a farmer's crop over a season. Which of the following correctly states a limitation imposed by the first or second law of thermodynamics?
Which of the following states the relevance of the first law of thermodynamics to biology?
Which of the following states the relevance of the first law of thermodynamics to biology?
Which is the most abundant form of energy in a cell?
Which is the most abundant form of energy in a cell?
Which of the following is an example of the second law of thermodynamics as it applies to biological reactions?
Which of the following is an example of the second law of thermodynamics as it applies to biological reactions?
According to the second law of thermodynamics, which of the following is true?
According to the second law of thermodynamics, which of the following is true?
If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?
If the entropy of a living organism is decreasing, which of the following is most likely to be occurring simultaneously?
Which of the following has the most free energy per molecule?
Which of the following has the most free energy per molecule?
The electronic arrangement in which of the following molecules means that this (these) molecule(s) has/have greater free energy than the others?
The electronic arrangement in which of the following molecules means that this (these) molecule(s) has/have greater free energy than the others?
Which part of the equation ΔG = ΔH - TΔS tells you if a process is spontaneous?
Which part of the equation ΔG = ΔH - TΔS tells you if a process is spontaneous?
If, during a process, the system becomes more ordered, then _____.
If, during a process, the system becomes more ordered, then _____.
When one molecule is broken down into six component molecules, which of the following will always be true?
When one molecule is broken down into six component molecules, which of the following will always be true?
From the equation ΔG = ΔH - TΔS it is clear that _____.
From the equation ΔG = ΔH - TΔS it is clear that _____.
An exergonic (spontaneous) reaction is a chemical reaction that _____.
An exergonic (spontaneous) reaction is a chemical reaction that _____.
Which of the following reactions would be endergonic?
Which of the following reactions would be endergonic?
Molecules A and B contain 110 kcal/mol of free energy and molecules B and C contain 150 kcal/mol of energy. A and B are converted to C and D. What can be concluded?
Molecules A and B contain 110 kcal/mol of free energy and molecules B and C contain 150 kcal/mol of energy. A and B are converted to C and D. What can be concluded?
Which of the following determines the sign of ΔG for a reaction?
Which of the following determines the sign of ΔG for a reaction?
Metabolic pathways in cells are typically far from equilibrium. Which of the following processes tend(s) to keep these pathways away from equilibrium?
Metabolic pathways in cells are typically far from equilibrium. Which of the following processes tend(s) to keep these pathways away from equilibrium?
Which of the following is an example of the cellular work accomplished with the free energy derived from the hydrolysis of ATP, involved in the production of electrochemical gradients?
Which of the following is an example of the cellular work accomplished with the free energy derived from the hydrolysis of ATP, involved in the production of electrochemical gradients?
In general, the hydrolysis of ATP drives cellular work by _____.
In general, the hydrolysis of ATP drives cellular work by _____.
Which of the following statements correctly describes some aspect of ATP hydrolysis being used to drive the active transport of an ion into the cell against the ion's concentration gradient?
Which of the following statements correctly describes some aspect of ATP hydrolysis being used to drive the active transport of an ion into the cell against the ion's concentration gradient?
Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because _____.
Much of the suitability of ATP as an energy intermediary is related to the instability of the bonds between the phosphate groups. These bonds are unstable because _____.
When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heat is given off as when 1 mole of ATP is hydrolyzed in a cell. Which of the following best explains these observations?
When 1 mole of ATP is hydrolyzed in a test tube without an enzyme, about twice as much heat is given off as when 1 mole of ATP is hydrolyzed in a cell. Which of the following best explains these observations?
What best characterizes the role of ATP in cellular metabolism?
What best characterizes the role of ATP in cellular metabolism?
The formation of glucose-6-phosphate from glucose is an endergonic reaction and is coupled to which of the following reactions or pathways?
The formation of glucose-6-phosphate from glucose is an endergonic reaction and is coupled to which of the following reactions or pathways?
A chemical reaction is designated as exergonic rather than endergonic when _____.
A chemical reaction is designated as exergonic rather than endergonic when _____.
Which of the following is changed by the presence of an enzyme in a reaction?
Which of the following is changed by the presence of an enzyme in a reaction?
What do the sign and magnitude of the ΔG of a reaction tell us about the speed of the reaction?
What do the sign and magnitude of the ΔG of a reaction tell us about the speed of the reaction?
How do enzymes lower activation energy?
How do enzymes lower activation energy?
All enzymes increase the rate of a reaction by raising the activation energy for reactions.
All enzymes increase the rate of a reaction by raising the activation energy for reactions.
In biological systems, processes that involve a decrease in entropy are often accompanied by an increase in _____ in the surroundings.
In biological systems, processes that involve a decrease in entropy are often accompanied by an increase in _____ in the surroundings.
What characterizes the relationship between exergonic and endergonic reactions?
What characterizes the relationship between exergonic and endergonic reactions?
Study Notes
Catabolism vs. Anabolism
- Catabolism involves breaking down molecules and releasing energy, while anabolism involves building complex molecules and requires energy input.
- Exergonic reactions release energy, while endergonic reactions absorb energy.
Enzymatic Activity
- Enzymes increase reaction rates without altering ΔG (Gibbs free energy) values.
- Reaction rate can be increased by adding more enzyme when substrate saturation occurs.
- Enzymes are specific and create an enzyme-substrate complex, facilitating chemical reactions.
Metabolic Processes
- Cellular respiration (C6H12O6 + 6 O2 → 6 CO2 + 6 H2O) is exergonic and does not require external energy input.
- The first and second laws of thermodynamics dictate energy flow and metabolism in organisms.
- Organisms are thermodynamically open systems, exchanging energy with their surroundings.
Thermodynamics in Biology
- ATP hydrolysis releases free energy, which can drive endergonic reactions through energy coupling.
- The increase in organization (decrease in entropy) in living systems requires constant energy input.
- Endergonic reactions, like forming glucose-6-phosphate from glucose, often couple with ATP hydrolysis.
Energy Transformations
- Enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) are critical in understanding reaction spontaneity and metabolic pathways.
- Exergonic reactions have a lower potential energy in products compared to reactants.
- Energy derived from glucose breakdown releases energy as heat.
Active Sites and Enzyme Function
- The active site of enzymes allows specific substrate binding and typically resembles a groove on the enzyme's surface.
- Temperature affects enzyme activity; low temperatures may limit the activation energy necessary for reactions to occur.
Misconceptions about Enzymes
- Enzymes are not consumed during the reactions they catalyze and can be reused.
- Enzymatic reactions can be saturated, meaning an increase in substrate won't increase the rate further.
Overall Metabolism
- ATP's instability in phosphate bonds makes it effective as an energy intermediary.
- Metabolic pathways are usually far from equilibrium, maintained by regular substrate removal and external energy input.### Induced Fit of Enzymes
- Enzymes change shape slightly when substrate binds, optimizing the fit between them and enhancing catalytic activity.
Role of Heat in Biological Reactions
- Heat is necessary for substrates to overcome activation energy barriers.
- Increased heat raises kinetic energy of substrates, which speeds up enzyme-catalyzed reactions.
Enzyme Saturation and Reaction Rate
- Above a certain substrate concentration, reaction rates may drop due to enzyme saturation.
- Increasing enzyme concentration or slightly raising temperature can enhance substrate conversion under saturation.
Factors Affecting Enzyme Activity
- pH, temperature, and substrate concentration all significantly influence enzyme activity.
- No environmental factor listed can be considered unaffected in their impact on enzyme reactions.
pH and Enzyme Activity
- High or low pH can disrupt hydrogen bonding and ionic interactions, altering the shape of the enzyme's active site, thus affecting its function.
Enzyme Inhibitors
- Competitive inhibitors may bind reversibly or irreversibly to the active site, decreasing enzyme activity.
- Noncompetitive inhibitors affect enzyme function but do not hinder substrate binding.
Succinylcholine as a Competitive Inhibitor
- Succinylcholine competes with acetylcholine at the active site, reducing acetylcholine hydrolysis rates until more acetylcholine is present.
Allosteric Regulation
- Allosteric regulation stabilizes the active form of enzymes via molecule binding, either enhancing or inhibiting activity.
Characteristics of Allosteric Proteins
- Allosteric proteins can be inhibited and are impacted by environmental changes, existing in both active and inactive forms.
Impact of Allosteric Inhibitors
- Allosteric inhibitors induce structural changes in enzymes, preventing substrate binding at the active site and reducing product formation.
Energy Regulation in Metabolic Pathways
- The balance of ATP and ADP levels regulates energy supply and demand in catabolic and anabolic pathways.
- High ADP levels activate catabolic pathways, promoting energy production.
Studying That Suits You
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Description
Test your knowledge on key concepts from Chapter 6 of AP Biology. This quiz includes questions related to catabolism, anabolism, and energy transformation in cells. Engage with flashcards designed to reinforce your understanding of biochemical processes.
