Untitled Quiz

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 heat means more kinetic energy, so the molecules move faster.

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

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

What also increases as a result of more heat?

Energy of the collisions also increases. Signup and view all the answers

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

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

What happens if the temperature gets too high?

The reaction stops. Signup and view all the answers

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

A rise in temperature makes the enzyme molecules vibrate more, which can break bonds that hold the enzyme in shape, changing the active site's shape. 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?

The enzyme becomes denatured. Signup and view all the answers

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

No longer functions as a catalyst. Signup and view all the answers

What does every enzyme have?

An optimum temperature. Signup and view all the answers

What is the optimum temperature of most human enzymes?

37 degrees Celsius. Signup and view all the answers

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

60 degrees Celsius. Signup and view all the answers

What shows how the rate of reaction changes with temperature?

Temperature coefficient - Q10. Signup and view all the answers

What does the temperature coefficient value show?

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

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

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

What does a Q10 value of 3 mean?

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

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

Around 2. Signup and view all the answers

What does pH affect?

Enzyme activity. Signup and view all the answers

What do all enzymes have?

An optimum pH value. Signup and view all the answers

What pH do most human enzymes work best at?

pH 7 - but there are exceptions. Signup and view all the answers

What pH does pepsin work best at?

Acidic pH 2 - useful because it's in the stomach. Signup and view all the answers

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

Ionic bonds and hydrogen bonds. Signup and view all the answers

What happens above and below the optimum pH?

The H+ ions and OH- ions found in acids and alkalis can mess up the ionic bonds and hydrogen bonds that hold the tertiary structure in place. Signup and view all the answers

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

The active site changes shape. Signup and view all the answers

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

Denatured. Signup and view all the answers

What does enzyme concentration affect?

Rate of reaction. Signup and view all the answers

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

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

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

Also increases the rate of reaction. Signup and view all the answers

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

It comes to a point when there's more than enough enzyme molecules to deal with the available substrate, so adding more enzymes has no effect. Signup and view all the answers

What does substrate concentration affect?

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

What happens if the substrate concentration is increased?

The rate of reaction increases. Signup and view all the answers

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

More substrate molecules mean a collision between substrate and enzyme molecules is more likely, so more active sites will be used. Signup and view all the answers

When does the rate of reaction stop increasing?

When the 'saturation' point is reached. Signup and view all the answers

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

Because there are so many substrate molecules that all the active sites are full, so adding more substrate makes no difference to the rate of reaction. Signup and view all the answers

What happens to substrate concentration over time during a reaction?

Substrate concentration decreases over time during a reaction. 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?

Rate of reaction will decrease over time too. Signup and view all the answers

What is the highest rate of reaction during the reaction?

The initial rate of reaction. Signup and view all the answers

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

You can measure how fast the product of the reaction appears or the disappearance of the substrate to compare the reaction under different conditions. Signup and view all the answers

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

Catalase. Signup and view all the answers

Why would catalase be a good example?

Easy to collect the oxygen produced and measure how fast it's given off. Signup and view all the answers

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

Fill a large beaker with water and place an upside-down measuring cylinder inside, place one end of a delivery tube inside the upside-down measuring cylinder, place the hydrogen peroxide solution and catalase into a test tube, quickly place the other end of the delivery tube over the top of the test tube and measure how much oxygen is produced using the upside-down measuring cylinder. Signup and view all the answers

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

Amylase - catalyses the breakdown of starch into maltose. Signup and view all the answers

What solution would you use to detect starch?

Solution of potassium iodide and iodine. Signup and view all the answers

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

By regularly sampling the starch solution. Signup and view all the answers

Why would you alter the conditions of the reaction?

To compare rates. Signup and view all the answers

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

Place the starch solution in a test tube and add amylase, every minute sample the mixture by using a pipette to take a sample and place it on the spotting tile, add the iodine in potassium iodide to the sample, time when the iodine solution no longer turns blue-black to note that starch has been broken down. 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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Untitled Quiz

Questions and Answers

What are the four factors that affect enzyme activity?

What happens when the temperature is increased?

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

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

What also increases as a result of more heat?

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

What happens if the temperature gets too high?

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

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

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

What does every enzyme have?

What is the optimum temperature of most human enzymes?

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

What shows how the rate of reaction changes with temperature?

What does the temperature coefficient value show?

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

What does a Q10 value of 3 mean?

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

What does pH affect?

What do all enzymes have?

What pH do most human enzymes work best at?

What pH does pepsin work best at?

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

What happens above and below the optimum pH?

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

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

What does enzyme concentration affect?

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

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

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

What does substrate concentration affect?

What happens if the substrate concentration is increased?

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

When does the rate of reaction stop increasing?

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

What happens to substrate concentration over time during a reaction?

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

What is the highest rate of reaction during the reaction?

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

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

Why would catalase be a good example?

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

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

What solution would you use to detect starch?

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

Why would you alter the conditions of the reaction?

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

Study Notes

Factors Affecting Enzyme Activity

Temperature Effects

Optimum Temperature

Temperature Coefficient (Q10)

pH Effects

Enzyme Concentration

Substrate Concentration

Measuring Reaction Rates

Experimental Methods

Studying That Suits You

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