Enzymes and Catalysts Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a catalyst?

A catalyst speeds up a reaction without itself being used up by the reaction.

What is the biological name for a catalyst?

Enzyme

Most enzymes are water-soluble.

True

Which of these options are true about enzymes? (Select all that apply)

Enzymes are not used up by the reaction. Signup and view all the answers

The name of most enzymes end in the suffix '-______'.

ase Signup and view all the answers

Give an example of a digestive enzyme that does not end in the suffix '-ase'.

Pepsin Signup and view all the answers

What is the chemical reaction catalyzed by sucrase?

The reaction of sucrose with water to form glucose and fructose. Signup and view all the answers

What is the name given to the complex that is formed when an enzyme binds with its substrate?

Enzyme-substrate complex Signup and view all the answers

The rate of a reaction can be increased by a factor of 10^6 - 10^12 when an enzyme is present.

True Signup and view all the answers

What molecule provides energy for the activation of chemical reactions?

Adenosine triphosphate (ATP) Signup and view all the answers

What is the term for the complicated folding that forms 'clefts' on the surface of the enzyme?

Active site Signup and view all the answers

Why does only one substrate fit into the active site?

The substrate has a particular geometry that fits the active site, and forms intermolecular interactions with the amino acid side chains. Signup and view all the answers

Describe the 'Lock and Key' model of enzyme action.

The shape of the substrate is complementary to the active site, where the substrate binds and the enzyme undergoes a catalyzed reaction. Signup and view all the answers

Describe the 'Induced-Fit' model of enzyme action.

The active site of the enzyme recognizes the substrate and then changes shape to completely surround it. Signup and view all the answers

What are the three factors that affect enzyme activity?

Interaction with other molecules Signup and view all the answers

What is the effect of increasing temperature on the activity of an enzyme?

As temperature increases, enzyme activity increases up to an optimal temperature. Signup and view all the answers

What is the effect of pH on the activity of an enzyme?

Most enzymes have an optimal pH, where the activity is highest, and activity can be reduced at higher or lower pH values, and may even denature the enzyme. Signup and view all the answers

Pepsin has an optimum pH close to that of salivary amylase.

False Signup and view all the answers

Study Notes

Enzymes

Enzymes are biological catalysts, speeding up reactions without being consumed.
They provide an alternative pathway with lower activation energy.
Living systems use enzymes as catalysts.
Most enzymes are water-soluble, globular proteins.
Enzymes function as biological catalysts.
Most enzymes are highly specific, recognizing only one specific substrate or type of substrate.

Intended Learning Outcomes

Students will describe the structure of enzymes.
Students will explain activation energy.
Students will describe factors affecting enzyme action.
Students will recognise enzyme function in different areas of the human body.

Catalysts

A catalyst accelerates a reaction without being used up by the reaction.
Catalysts offer an alternative reaction pathway with reduced activation energy.

Enzyme Names

Enzyme names typically end in "-ase."
Common digestive enzyme names end in "-in" (e.g., pepsin, trypsin).
Some enzyme names incorporate the substrate (e.g., sucrase).
Enzyme names can also describe their function (e.g., oxidase, hydrolase).

Enzymes Lower Activation Energies

Enzymes function by forming complexes with substrates, stabilizing them and decreasing activation energy.
E + S → ES → P (Enzyme + Substrate → Enzyme-Substrate complex → Product).
Reaction rates can increase by a factor of 10⁶ - 10¹² with enzymes.

Energy for Activation

Energy for reactions comes from the hydrolysis of adenosine triphosphate (ATP).
ATP + H₂O → ADP + P_i + energy

Enzyme Shape and Reactivity

The active site is a specific region on an enzyme's surface with a unique shape.
Enzyme recognition occurs when a substrate fits the active site shape.
Intermolecular interactions between the substrate and amino acid side chains within the active site are crucial.

Fischer “Lock and Key” Model

Substrate-enzyme binding resembles a key fitting into a lock.
Only one type of substrate fits into an enzyme's active site.
An enzyme-substrate complex forms, mediating the catalyzed reaction.

Induced-Fit Model

A more advanced model.
The active site's shape changes slightly when a substrate binds.
The conformational change enhances the fit of the substrate.
A more perfect substrate-enzyme fit is achieved.
Substrate binds to active site and enzyme changes shape.

Catalytic Cycle of an Enzyme

Substrates bind to the active site, creating an enzyme-substrate complex.
The complex undergoes internal rearrangements, forming products.
The enzyme releases the reaction's products.

Factors Affecting Enzyme Activity

Enzyme activity depends on three factors:
- The enzyme's three-dimensional structure (anything affecting structure affects function).
- Substrate and enzyme concentration.
- Interactions with other molecules (inhibition or regulation occurring at the active site or elsewhere on the protein surface).

Enzyme Activity - Enzyme Structure

Enzyme structure is governed by weak intermolecular interactions controlling tertiary structure.
Changes affecting tertiary structure affect enzyme activity.

Enzyme Activity - Effect of Temperature

Low temperatures result in slow enzyme activity.
Molecules collide less frequently due to lower speeds.
Insufficient energy to overcome activation energy.
Activity increases up to an optimum temperature.
Molecules move faster and collide more.
Above the optimum temperature (over 40°C), many enzymes denature.

Enzyme Activity - Effect of pH

Most enzymes operate within a narrow pH range.
Large changes in pH can denature enzymes.
Disrupt the precise three-dimensional arrangements of proteins.
Smaller pH changes affect substrate and/or enzyme side chain ionization.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on enzymes, their structure, and function as biological catalysts. This quiz covers key concepts like activation energy, enzyme specificity, and factors affecting enzyme action in the human body. Perfect for students learning about biochemistry and enzymology.