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Questions and Answers
What is the optimal pH for pepsin activity?
What is the optimal pH for pepsin activity?
What happens to enzyme activity if the pH moves away from the optimum pH?
What happens to enzyme activity if the pH moves away from the optimum pH?
What is the consequence of continuously decreasing substrate concentration over time in an enzymatic reaction?
What is the consequence of continuously decreasing substrate concentration over time in an enzymatic reaction?
How do metal ion activators affect enzymatic reactions?
How do metal ion activators affect enzymatic reactions?
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Which statement is true about substrate concentration in enzymatic reactions?
Which statement is true about substrate concentration in enzymatic reactions?
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What is a potential effect of enzyme concentration on reaction rate?
What is a potential effect of enzyme concentration on reaction rate?
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What role do coenzymes play in enzymatic reactions?
What role do coenzymes play in enzymatic reactions?
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Which factor is least likely to affect enzyme activity?
Which factor is least likely to affect enzyme activity?
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What initiates the action of pancreatic enzymes on denatured proteins?
What initiates the action of pancreatic enzymes on denatured proteins?
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What term describes the saturation of an enzyme with substrate at its maximum reaction rate?
What term describes the saturation of an enzyme with substrate at its maximum reaction rate?
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What is the primary effect of increasing temperature on enzyme activity up to the optimum temperature?
What is the primary effect of increasing temperature on enzyme activity up to the optimum temperature?
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What occurs to the enzyme when the temperature exceeds the optimum range of 60-65 °C?
What occurs to the enzyme when the temperature exceeds the optimum range of 60-65 °C?
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Which of the following factors is NOT mentioned as affecting enzyme activity?
Which of the following factors is NOT mentioned as affecting enzyme activity?
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The optimum pH for most enzymes is generally in which range?
The optimum pH for most enzymes is generally in which range?
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What aspect of enzyme activity does the term 'optimum temperature' refer to?
What aspect of enzyme activity does the term 'optimum temperature' refer to?
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What is the effect of pH on enzyme structure?
What is the effect of pH on enzyme structure?
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How does the concentration of a substrate affect the reaction rate of enzymes with low Km?
How does the concentration of a substrate affect the reaction rate of enzymes with low Km?
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Which enzyme has an optimum pH of approximately 1.5 - 2?
Which enzyme has an optimum pH of approximately 1.5 - 2?
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What does the Michaelis constant (Km) specifically indicate?
What does the Michaelis constant (Km) specifically indicate?
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What role do coenzymes play in enzyme activity?
What role do coenzymes play in enzyme activity?
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In a Lineweaver-Burk plot, what does the Y-intercept represent?
In a Lineweaver-Burk plot, what does the Y-intercept represent?
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Which of the following statements about enzyme concentration is true?
Which of the following statements about enzyme concentration is true?
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What happens to the rate of reaction when a substrate's concentration is high enough to saturate the enzyme?
What happens to the rate of reaction when a substrate's concentration is high enough to saturate the enzyme?
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Which statement best describes competitive inhibitors?
Which statement best describes competitive inhibitors?
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Which factors are known to affect the rate of enzyme activity?
Which factors are known to affect the rate of enzyme activity?
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What is true about enzymes with a high Km?
What is true about enzymes with a high Km?
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Why is the Lineweaver-Burk plot advantageous for determining Vmax?
Why is the Lineweaver-Burk plot advantageous for determining Vmax?
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Enzyme kinetics primarily studies which of the following?
Enzyme kinetics primarily studies which of the following?
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What is the relationship between enzyme concentration and reaction rate?
What is the relationship between enzyme concentration and reaction rate?
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Which model of enzyme action does suggest that the enzyme's active site changes to fit the substrate?
Which model of enzyme action does suggest that the enzyme's active site changes to fit the substrate?
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Study Notes
Factors Affecting Enzyme Activity
- Enzyme activity is influenced by various factors
- Factors affecting enzyme activity include temperature, pH, time, concentration of coenzymes, concentration of ion activators, enzyme concentration, substrate concentration, and inhibitors.
Temperature Effects
- Reaction rate increases as temperature rises, up to a maximum at a specific temperature known as the optimum temperature
- Optimum temperature is when the maximum amount of substrate converts to products
- Optimal temperature for humans ranges between 37-40°C
- Increase in temperature initially increases the initial energy of the substrate, which decreases the activation energy, and increases the collision of molecules
- After the optimum temperature the reaction rate decreases due to enzyme denaturation (at 60-65°C)
pH Effects
- Each enzyme has an optimum pH at which its activity is highest
- Examples of enzymes and their optimum pH values:
- Pepsin: 1.5-2
- Pancreatic enzymes: 7.5-8
- Salivary amylase: 6.8
- Optimal pH for most enzymes is 7.35-7.45
- Change in pH above or below optimal pH reduces enzyme activity due to ionization state changes of the enzyme and substrate active sites, potentially leading to denaturation
Time Effects
- In an enzymatically catalyzed reaction, the reaction rate decreases over time
- This can be due to:
- Substrate depletion (exhaustion of substrate)
- Accumulation of end products (which can cause feedback inhibition)
- Change in pH away from the optimum pH
Coenzymes and Ion Activators
- Coenzymes: Increase in coenzyme concentration will increase the reaction rate in conjugated enzymes requiring coenzymes.
- Ion activators: An increase in metal ion activator concentration will increase the reaction rate
Enzyme Concentration
- The rate of an enzyme-catalyzed reaction is directly proportional to the enzyme concentration, given sufficient substrate and constant conditions
Substrate Concentration
- Reaction rate increases as substrate concentration rises until a maximum rate (Vmax) is reached
- At Vmax, the enzyme is saturated with substrate, and any further increase in substrate concentration does not affect the reaction rate
Enzyme Kinetics
- Enzyme kinetics studies the rate at which an enzyme acts
- Key concepts:
- Michaelis constant (Km): The substrate concentration producing half the maximum velocity of the enzyme
- High Km: low affinity of the enzyme for the substrate. The enzyme reaches maximum velocity only at high substrate concentrations
- Low Km: high affinity for the substrate. The enzyme reaches maximum velocity even at low substrate concentrations
Enzyme Inhibitors
- Enzyme inhibitors reduce or stop enzyme activity.
- Types of enzyme inhibitors:
- Competitive inhibitors
- Non-competitive inhibitors
Summary of Factors Affecting Enzyme Activity
- Temperature, pH, time, coenzyme concentration, ion activator concentration, enzyme concentration, substrate concentration, and inhibitors all affect enzyme activity.
- Understanding these factors is crucial to controlling enzymatic reactions in biological systems
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Description
Explore the critical factors that influence enzyme activity, including temperature and pH levels. Understand how these environmental conditions impact the reaction rates and the efficiency of enzymes. This quiz covers specific examples and optimal conditions for various enzymes.
