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Questions and Answers
What happens to the reaction velocity when the substrate concentration is increased?
What happens to the reaction velocity when the substrate concentration is increased?
- It remains constant
- It fluctuates randomly
- It decreases
- It increases until a saturation point is reached (correct)
What is the effect of extreme pH levels on enzyme activity?
What is the effect of extreme pH levels on enzyme activity?
- It denatures the enzyme, changing its structure (correct)
- It increases the reaction rate
- It has no effect on the reaction rate
- It only affects the substrate molecules
What is the Q10 temperature coefficient?
What is the Q10 temperature coefficient?
- A measure of the decrease in reaction rate with a 10°C rise in temperature
- A measure of the increase in reaction rate with a 10°C rise in temperature (correct)
- A measure of the substrate concentration required for enzyme saturation
- A measure of the optimum pH for an enzyme-controlled reaction
Why does the reaction velocity change when the enzyme concentration is altered?
Why does the reaction velocity change when the enzyme concentration is altered?
What happens to the enzyme's active site at extreme pH levels?
What happens to the enzyme's active site at extreme pH levels?
What is the effect of a small change in pH on enzyme activity?
What is the effect of a small change in pH on enzyme activity?
What is the balance that determines the optimum temperature for an enzyme-controlled reaction?
What is the balance that determines the optimum temperature for an enzyme-controlled reaction?
What is the effect of increasing the enzyme concentration on the Vmax?
What is the effect of increasing the enzyme concentration on the Vmax?
Why do enzyme-controlled reactions follow the Q10 rule?
Why do enzyme-controlled reactions follow the Q10 rule?
What happens to the enzyme structure at high temperatures?
What happens to the enzyme structure at high temperatures?
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Study Notes
Enzymes and Catalysis
- Enzymes are proteins with catalytic properties that increase reaction rates without raising temperature.
- They lower the activation energy, creating an alternative reaction pathway.
Activation Energy
- Activation energy is the initial energy required for a chemical reaction to proceed.
- Molecules enter a transition state during this stage of the reaction.
Reaction Rate Enhancement
- Increasing temperature accelerates molecular movement; however, biological systems are sensitive to temperature changes.
- Enzymes can increase reaction speed by factors of 10^8 to 10^11 compared to non-enzymatic reactions.
Enzyme Structure
- Enzymes possess a globular shape and a complex three-dimensional structure.
- Human pancreatic amylase is an example of an enzyme.
Enzyme Activity Hypotheses
- Lock and Key Hypothesis: Describes enzyme specificity and results in loss of activity due to denaturation.
- Induced Fit Hypothesis: Enzyme shape changes upon substrate binding, optimizing the environment for the reaction and lowering activation energy further.
Factors Affecting Enzyme Activity
- Substrate Concentration:
- In enzymatic reactions, increased substrate concentration increases reaction velocity until a saturation point is reached (all enzyme active sites occupied).
- Altering enzyme concentration can change maximum reaction velocity (Vmax).
- pH:
- Each enzyme has an optimum pH for maximum activity; extreme pH levels can denature enzymes, distorting their active sites.
- Small changes in pH near the optimum can affect substrate binding due to ionization alterations.
- Temperature:
- The Q10 coefficient indicates reaction rate increases by 2 to 3 for every 10°C temperature rise in chemical reactions.
- Enzyme reactions obey this rule, but excessive heat can lead to protein denaturation; the optimum temperature is a balance between activity and stability.
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