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Factors Affecting Enzyme Activity
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Factors Affecting Enzyme Activity

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@DistinctiveDrama

Questions and Answers

What are the four factors that affect enzyme activity?

Temperature, pH, enzyme concentration, substrate concentration.

What happens when the temperature is increased?

The rate of an enzyme-controlled reaction increases.

What does more heat mean for the molecules in an enzyme-controlled reaction?

More kinetic energy, so the molecules move faster.

If the molecules move faster, what is more likely to happen?

<p>Enzymes are more likely to collide with the substrate molecules.</p> Signup and view all the answers

What also increases as a result of more heat?

<p>Energy of the collisions also increases.</p> Signup and view all the answers

If the energy of the collisions increases, what are the collisions more likely to result in?

<p>Collisions are more likely to result in a reaction.</p> Signup and view all the answers

What happens if the temperature gets too high?

<p>The reaction stops.</p> Signup and view all the answers

Explain why if the temperature gets too high the reaction stops.

<p>A rise in temperature makes enzyme molecules vibrate more, breaking bonds that hold the structure.</p> Signup and view all the answers

What does the enzyme become if the active site changes shape and the enzyme and substrate no longer fit?

<p>The enzyme becomes denatured.</p> Signup and view all the answers

What does the enzyme no longer function as if it becomes denatured?

<p>No longer functions as a catalyst.</p> Signup and view all the answers

What does every enzyme have?

<p>An optimum temperature.</p> Signup and view all the answers

What is the optimum temperature of most human enzymes?

<p>37 degrees Celsius.</p> Signup and view all the answers

What is the optimum temperature for some enzymes, such as those used in biological washing powders?

<p>60 degrees Celsius.</p> Signup and view all the answers

What shows how the rate of reaction changes with temperature?

<p>Temperature coefficient - Q10.</p> Signup and view all the answers

What does the temperature coefficient value show?

<p>How much the rate of reaction changes when the temperature is raised by 10 degrees Celsius.</p> Signup and view all the answers

At temperatures before the optimum, what does a Q10 value of 2 mean?

<p>That the rate doubles when the temperature is raised by 10 degrees Celsius.</p> Signup and view all the answers

What does a Q10 value of 3 mean?

<p>The rate trebles when the temperature is raised by 10 degrees Celsius.</p> Signup and view all the answers

What is the Q10 value of most enzyme-controlled reactions?

<p>Around 2.</p> Signup and view all the answers

What does pH affect?

<p>Enzyme activity.</p> Signup and view all the answers

What do all enzymes have?

<p>An optimum pH value.</p> Signup and view all the answers

What pH do most human enzymes work best at?

<p>pH 7 - but there are exceptions.</p> Signup and view all the answers

What pH does pepsin work best at?

<p>Acidic pH 2.</p> Signup and view all the answers

What bonds hold the enzyme's tertiary structure in place?

<p>Ionic bonds and hydrogen bonds.</p> Signup and view all the answers

What happens above and below the optimum pH?

<p>The H+ ions and OH- ions can disrupt the ionic and hydrogen bonds.</p> Signup and view all the answers

What happens to the enzyme's active site if the ionic and hydrogen bonds are affected?

<p>The active site changes shape.</p> Signup and view all the answers

What does the enzyme become if the active site changes shape?

<p>Denatured.</p> Signup and view all the answers

What does enzyme concentration affect?

<p>Rate of reaction.</p> Signup and view all the answers

What is more likely to happen if there are more enzyme molecules in a solution?

<p>The more enzyme molecules in a solution, the more likely a substrate molecule is to collide and form an enzyme-substrate complex.</p> Signup and view all the answers

Therefore, what does increasing the concentration of the enzyme increase also?

<p>Also increases the rate of reaction.</p> Signup and view all the answers

What happens if the amount of substrate is limited and you keep adding more enzyme molecules?

<p>It comes to a point where there’s more than enough enzyme molecules, so adding more has no effect.</p> Signup and view all the answers

What does substrate concentration affect?

<p>Substrate concentration affects the rate of the reaction up until a point.</p> Signup and view all the answers

What happens if the substrate concentration is increased?

<p>The rate of reaction increases.</p> Signup and view all the answers

Why does the rate of reaction increase if the substrate concentration is higher?

<p>More substrate molecules means a collision between substrate and enzyme molecules is more likely.</p> Signup and view all the answers

When does the rate of reaction stop increasing?

<p>When the 'saturation' point is reached.</p> Signup and view all the answers

Why does the rate of reaction stop increasing after the saturation point is reached?

<p>Because there are so many substrate molecules that all the active sites are full.</p> Signup and view all the answers

What happens to substrate concentration over time during a reaction?

<p>Substrate concentration decreases over time during a reaction.</p> Signup and view all the answers

If the substrate concentration decreases over time and no other variables are changed in the reaction, what will happen to the rate of reaction?

<p>The rate of reaction will decrease over time too.</p> Signup and view all the answers

What is the highest rate of reaction during the reaction?

<p>The initial rate of reaction.</p> Signup and view all the answers

Name two ways you can measure the rate of an enzyme-controlled reaction.

<p>Measure how fast the product appears or the disappearance of the substrate.</p> Signup and view all the answers

What enzyme would you use to measure how fast a product appears?

<p>Catalase.</p> Signup and view all the answers

Why would catalase be a good example?

<p>It is easy to collect the oxygen produced and measure how fast it's given off.</p> Signup and view all the answers

How would you measure the appearance of a product using catalase?

<p>Fill a large beaker with water, place an upside-down measuring cylinder inside, connect a delivery tube, and measure the oxygen produced.</p> Signup and view all the answers

What enzyme would you use to measure the disappearance of the substrate?

<p>Amylase.</p> Signup and view all the answers

What solution would you use to detect starch?

<p>Solution of potassium iodide and iodine.</p> Signup and view all the answers

How would you time how long it takes for the starch to disappear?

<p>By regularly sampling the starch solution.</p> Signup and view all the answers

Why would you alter the conditions of the reaction?

<p>To compare reaction rates.</p> Signup and view all the answers

Describe how you would use amylase to measure the disappearance of a substrate.

<p>Place starch solution in a test tube, add amylase, sample regularly, add iodine, and time until color change.</p> Signup and view all the answers

Study Notes

Factors Affecting Enzyme Activity

  • Four main factors influencing enzyme activity: temperature, pH, enzyme concentration, and substrate concentration.

Temperature Effects

  • Increased temperature raises the rate of enzyme-controlled reactions.
  • Higher temperatures provide more kinetic energy, causing molecules to move faster.
  • Faster-moving molecules lead to a higher likelihood of collisions between enzymes and substrates.
  • Increased kinetic energy also boosts the energy of collisions, making reactions more probable.
  • If temperatures exceed a certain threshold, enzyme activity halts; excessive heat denatures enzymes.
  • High temperatures cause vibrations in enzyme molecules, breaking bonds that maintain their shape, altering the active site.
  • An altered active site renders the substrate unable to bind, resulting in a denatured enzyme.

Optimum Temperature

  • Every enzyme has an optimum temperature; for most human enzymes, this is approximately 37 degrees Celsius.
  • Some enzymes, like those in biological washing powders, may have an optimum temperature of around 60 degrees Celsius.

Temperature Coefficient (Q10)

  • Q10 indicates how much the reaction rate changes with a 10-degree Celsius increase.
  • A Q10 value of 2 means the rate doubles; a value of 3 signifies a tripling in reaction rate.

pH Effects

  • pH significantly affects enzyme activity as each enzyme has an optimum pH level.
  • Most human enzymes function best at pH 7, though there are exceptions.
  • Pepsin, an enzyme in the stomach, operates optimally at a highly acidic pH of 2.
  • Ionic and hydrogen bonds maintain the enzyme's tertiary structure; deviations in pH can disrupt these bonds.
  • Changes in pH can deform the active site, leading to enzyme denaturation.

Enzyme Concentration

  • Enzyme concentration directly impacts reaction rates. More enzyme molecules heighten Collision likelihood with substrate, increasing reaction rates.
  • If substrate availability is limited, adding excess enzymes eventually yields no additional effect, as all active sites may be occupied.

Substrate Concentration

  • Higher substrate concentrations generally lead to increased reaction rates until reaching a saturation point.
  • Once saturation is hit, adding more substrate won't enhance the rate since all active sites are engaged.
  • During reactions, substrate concentration declines over time, causing the reaction rate to drop.

Measuring Reaction Rates

  • Initial reaction rate is the fastest during the process.
  • Two methods for measuring enzyme activity include quantifying product formation and substrate depletion.
  • Catalase is effective for measuring product appearance, particularly oxygen production.
  • For substrate disappearance, amylase can be used to break down starch into maltose; starch presence can be monitored using iodine solution.

Experimental Methods

  • For catalase, use water displacement in a measuring cylinder to collect produced oxygen.
  • For amylase assays, periodically sample the reaction mixture and add iodine to detect starch breakdown, noting when the blue-black color disappears.

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Description

Explore the key factors influencing enzyme activity including temperature, pH, enzyme concentration, and substrate concentration. This quiz delves into how temperature changes can affect the rate of enzyme-controlled reactions and the concept of optimum temperature for enzymes.

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