Enzyme Basics and Specificity

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Questions and Answers

What is the independent variable plotted on the x-axis in enzyme rate experiments?

Enzyme concentration

Rate of reaction

Substrate concentration (correct)

Temperature

Enzyme rate experiments can only measure how much product is produced.

False

Name one factor that can be changed in enzyme rate experiments.

Temperature, pH, enzyme concentration, or substrate concentration

A _____ of best fit can be used to interpret or extrapolate data from enzyme rate graphs.

line Signup and view all the answers

What is the primary function of enzymes?

To speed up chemical reactions without being consumed Signup and view all the answers

Enzymes can only function inside cells.

False Signup and view all the answers

What is one method of measuring the rate of a reaction in enzyme experiments?

Using a gas cylinder to collect oxygen Signup and view all the answers

What is the role of the active site in an enzyme?

It is where the substrate binds. Signup and view all the answers

Match the following enzyme concentration factors with their effect on reaction rate:

Increasing temperature = Increases rate up to a point Decreasing pH = Can denature the enzyme Increasing substrate concentration = Increases rate until saturation Increasing enzyme concentration = Accelerates the reaction rate Signup and view all the answers

What conclusion can be made using extrapolation from a graph?

Predictions can be made beyond the range of existing data points. Signup and view all the answers

Enzymes are classified as __________ proteins.

globular Signup and view all the answers

Match the following terms with their descriptions:

Intracellular enzymes = Function inside the cell Extracellular enzymes = Secreted by cells to act outside Biological catalyst = Substance that speeds up reactions Metabolic pathways = Series of chemical reactions controlled by enzymes Signup and view all the answers

Line graphs are not suitable for presenting the results of enzyme rate experiments.

False Signup and view all the answers

Which of the following statements about enzymes is true?

Enzymes are essential for nearly every metabolic reaction in living organisms. Signup and view all the answers

Enzymes can only function at specific temperatures and pH levels.

True Signup and view all the answers

Name one example of an extracellular enzyme.

Digestive enzymes in the gut. Signup and view all the answers

What is the independent variable in an enzyme rate experiment that investigates the effect of temperature?

Temperature Signup and view all the answers

The initial rate of reaction is represented by the final gradient of the lines on the graph.

False Signup and view all the answers

What should be included when labeling the axes of a graph?

Units Signup and view all the answers

In enzyme rate experiments, a line of best-fit should be ______ and should have a balance of data points above and below it.

smooth Signup and view all the answers

Match the following aspects of graph creation with their descriptions:

Plot data points accurately = Ensure reliability of the graph Choose appropriate scales = Data fits within the graph area Label axes = Provide information about variables Draw a line of best-fit = Identify trends in the data Signup and view all the answers

When is it necessary to plot more than one set of data on the same graph?

When comparing rates at different temperatures Signup and view all the answers

When creating graphs for enzyme experiments, the scales on the axes can be arbitrary.

False Signup and view all the answers

What must be done if the concentration of enzyme or substrate is 0?

The reaction cannot occur. Signup and view all the answers

What happens to enzymes at extremes of pH?

They denature. Signup and view all the answers

All enzymes work best at a neutral pH of 7.

False Signup and view all the answers

What is the optimum pH for pepsin?

pH 2 Signup and view all the answers

Enzyme-substrate complexes form less easily when the shape of the ____________ is altered.

active site Signup and view all the answers

Match the following terms related to enzyme activity:

Optimum pH = pH at which an enzyme operates best Denaturation = Loss of enzyme structure and function Active site = Region where substrate binds to enzyme Hydrogen bonds = Types of bonds that help maintain enzyme structure Signup and view all the answers

What effect do excess H+ ions in acidic solutions have on enzymes?

They can break ionic and hydrogen bonds in the enzyme. Signup and view all the answers

Once an enzyme is denatured, it can regain its original function.

False Signup and view all the answers

What are the two types of ions in alkaline solutions that can affect enzyme structure?

OH- ions Signup and view all the answers

Which statement is true regarding competitive inhibitors?

They compete with the substrate for the active site. Signup and view all the answers

Non-competitive inhibitors can be overcome by increasing substrate concentration.

False Signup and view all the answers

What is the effect of increasing inhibitor concentration on the rate of reaction?

It reduces the rate of reaction and can stop it completely. Signup and view all the answers

The shape of the active site is altered by __________ inhibitors.

non-competitive Signup and view all the answers

What happens to the amount of product produced by a competitive inhibitor compared to the reaction without the inhibitor?

It remains the same at maximal rates. Signup and view all the answers

Match the type of inhibitor to its effect on enzyme activity:

Competitive Inhibitor = Initial rate lowered but maximal rate unchanged Non-competitive Inhibitor = Both initial and maximal rates lowered Signup and view all the answers

Increasing the concentration of a __________ can sometimes compensate for a competitive inhibitor.

substrate Signup and view all the answers

What is the role of an inhibitor in an enzyme-catalysed reaction?

To slow down or stop enzyme activity. Signup and view all the answers

What does the lock and key model suggest about enzyme action?

The active site and substrate fit together perfectly. Signup and view all the answers

The induced fit model suggests that the active site of the enzyme is rigid.

False Signup and view all the answers

What technique provides 3D images that confirm changes in enzyme shape?

X-ray diffraction Signup and view all the answers

The ___ movement of an enzyme occurs when a substrate binds to it.

larger Signup and view all the answers

Match the following models of enzyme action with their descriptions:

Lock and Key Model = Active site shape is a perfect fit for the substrate Induced Fit Model = Active site changes shape to fit the substrate Rigid Model = Suggests that proteins do not change shape Flexible Model = Allow for movements in enzyme structure Signup and view all the answers

What was a primary limitation of the lock and key model?

It doesn't account for the dynamic nature of enzyme structure. Signup and view all the answers

New research has disproven the lock and key model in favor of the induced fit model.

True Signup and view all the answers

What is the primary change in an enzyme when its substrate binds to it according to the induced fit model?

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

Study Notes

Enzyme Basics

Enzymes are biological catalysts, speeding up reactions without being changed
They are globular proteins
Active sites are crucial for substrate binding
Enzymes are specific due to the complementary shapes of active sites and substrates

Enzyme Specificity

Active sites have a precise shape to fit a specific substrate.
Extreme changes in temperature or pH can denature enzymes, altering active site shape.
This prevents substrate binding and thus, halts the reaction

Enzyme Action

The lock-and-key model describes enzymes as rigid structures that fit precisely into substrates.
The induced-fit model is the more current model. It suggests the enzyme's active site changes shape slightly to accommodate substrate.
This improves binding and facilitates the reaction.

Enzyme Rate Experiments

Enzyme reactions can be studied by measuring product formation or substrate disappearance.
Factors influencing enzyme activity are often investigated, such as temperature, pH, enzyme concentration, substrate concentration and inhibitors.
Precise measurements are integral and need to account for uncertainty.

Limiting Factors

Temperature: Higher temperatures increase reaction rates, but very high temps lead to enzyme denaturation.
pH: Enzymes have an optimal pH; deviations can cause denaturation.
Enzyme concentration: Increasing the enzyme concentration increases the reaction rate at first until the substrate becomes the limiting factor.
Substrate concentration: Increasing the substrate concentration initially increases the reaction rate, but will plateau when all enzyme active sites are saturated.
Inhibitors: Inhibitors (competitive and noncompetitive) bind to the enzyme and decrease reaction rates. Enzyme inhibitors can be either reversible or irreversible.

Practical Skills

Controlling variables: Researchers must carefully hold many aspects of an experiment constant to ensure only the one independent variable being studied affects the reaction rate.
Calculating uncertainty: Determining the margin of error in measurements is important for reliable results.

Studying That Suits You

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Description

This quiz covers the fundamentals of enzyme action, including enzyme specificity and the mechanisms by which they function. You'll explore the lock-and-key and induced-fit models, as well as factors affecting enzyme activity. Test your knowledge and deepen your understanding of these vital biological catalysts.

Enzyme Basics and Specificity

Choose a study mode

Podcast

Questions and Answers

What is the independent variable plotted on the x-axis in enzyme rate experiments?

Enzyme rate experiments can only measure how much product is produced.

Name one factor that can be changed in enzyme rate experiments.

A _____ of best fit can be used to interpret or extrapolate data from enzyme rate graphs.

What is the primary function of enzymes?

Enzymes can only function inside cells.

What is one method of measuring the rate of a reaction in enzyme experiments?

What is the role of the active site in an enzyme?

Match the following enzyme concentration factors with their effect on reaction rate:

What conclusion can be made using extrapolation from a graph?

Enzymes are classified as __________ proteins.

Match the following terms with their descriptions:

Line graphs are not suitable for presenting the results of enzyme rate experiments.

Which of the following statements about enzymes is true?

Enzymes can only function at specific temperatures and pH levels.

Name one example of an extracellular enzyme.

What is the independent variable in an enzyme rate experiment that investigates the effect of temperature?

The initial rate of reaction is represented by the final gradient of the lines on the graph.

What should be included when labeling the axes of a graph?

In enzyme rate experiments, a line of best-fit should be ______ and should have a balance of data points above and below it.

Match the following aspects of graph creation with their descriptions:

When is it necessary to plot more than one set of data on the same graph?

When creating graphs for enzyme experiments, the scales on the axes can be arbitrary.

What must be done if the concentration of enzyme or substrate is 0?

What happens to enzymes at extremes of pH?

All enzymes work best at a neutral pH of 7.

What is the optimum pH for pepsin?

Enzyme-substrate complexes form less easily when the shape of the ____________ is altered.

Match the following terms related to enzyme activity:

What effect do excess H+ ions in acidic solutions have on enzymes?

Once an enzyme is denatured, it can regain its original function.

What are the two types of ions in alkaline solutions that can affect enzyme structure?

Which statement is true regarding competitive inhibitors?

Non-competitive inhibitors can be overcome by increasing substrate concentration.

What is the effect of increasing inhibitor concentration on the rate of reaction?

The shape of the active site is altered by __________ inhibitors.

What happens to the amount of product produced by a competitive inhibitor compared to the reaction without the inhibitor?

Match the type of inhibitor to its effect on enzyme activity:

Increasing the concentration of a __________ can sometimes compensate for a competitive inhibitor.

What is the role of an inhibitor in an enzyme-catalysed reaction?

What does the lock and key model suggest about enzyme action?

The induced fit model suggests that the active site of the enzyme is rigid.

What technique provides 3D images that confirm changes in enzyme shape?

The ___ movement of an enzyme occurs when a substrate binds to it.

Match the following models of enzyme action with their descriptions:

What was a primary limitation of the lock and key model?

New research has disproven the lock and key model in favor of the induced fit model.

What is the primary change in an enzyme when its substrate binds to it according to the induced fit model?

Study Notes

Enzyme Basics

Enzyme Specificity

Enzyme Action

Enzyme Rate Experiments

Limiting Factors

Practical Skills

Studying That Suits You

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