Enzymes: Biological Catalysts Quiz

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Questions and Answers

What is a catalyst?

A catalyst is a substance that speeds up the rate of a chemical reaction, without entering the reaction itself.

Catalysts can be inorganic or organic.

True (A)

What are enzymes?

Enzymes are organic catalysts made of protein.

Most enzymes end in the suffix -ase.

True (A) Signup and view all the answers

How do enzymes work?

Enzymes lower the activation energy needed to start a chemical reaction. Signup and view all the answers

What does the lock and key model explain?

The lock and key model explains how enzymes fit into their substrates. Signup and view all the answers

What are the steps of enzyme action? (Select all that apply)

Enzyme joins with its substrate (A), The enzyme is unchanged and can be reused (B), Enzyme and substrate form an enzyme-substrate complex (C), Enzyme action takes place (D), Enzyme and products separate (E) Signup and view all the answers

The induced fit model describes a rigid enzyme that does not change shape.

False (B) Signup and view all the answers

What are coenzymes and cofactors?

Enzyme helpers (C) Signup and view all the answers

Enzymes can operate under any conditions.

False (B) Signup and view all the answers

Which of the following factors affect enzyme action? (Select all that apply)

Concentration of enzymes (A), Temperature (B), Concentration of substrates (C), pH (D) Signup and view all the answers

What is the optimal pH for pepsin, an enzyme in the stomach?

2 Signup and view all the answers

What is the optimal pH for amylase, an enzyme found in the mouth?

6.8 Signup and view all the answers

What is the optimal temperature for enzymes in humans?

37°C Signup and view all the answers

Enzymes can change shape when the temperature gets too high.

True (A) Signup and view all the answers

What happens to an enzyme when it is denatured?

It cannot bind with its substrate. Signup and view all the answers

Changes in pH can also denature enzymes.

True (A) Signup and view all the answers

How does the concentration of enzymes and substrates affect enzyme action?

It increases the rate of enzyme action to a certain point, and then levels off. Signup and view all the answers

What is the difference between a substrate and an active site?

A substrate is the molecule that an enzyme acts on, while the active site is the region on the enzyme where the substrate binds. Signup and view all the answers

What type of biological molecule is an enzyme considered?

A protein Signup and view all the answers

Why is enzyme action similar to the action of a key fitting into a lock?

The enzyme's active site has a specific shape that matches the shape of its substrate. Signup and view all the answers

Why are changes in pH and temperature critical to the proper functioning of an enzyme?

They can denature enzymes. Signup and view all the answers

Study Notes

Enzymes: Biological Catalysts

Enzymes are biological catalysts
Catalysts speed up chemical reactions without being consumed
Most catalysts are organic, meaning they contain carbon
Enzymes are organic catalysts made of protein
Enzyme names typically end in -ase
Enzymes lower the activation energy of a reaction, allowing for faster reactions

How Catalysts Work

Catalysts speed up chemical reactions by lowering the activation energy
Activation energy is the minimum energy required to initiate a chemical reaction
Enzymes do not change the overall energy released or consumed during the reaction
Enzymes function by binding to substrates at the active site
The active site is a specific region on an enzyme

Enzyme Structure and Function

Enzymes typically have a larger structure than their substrates
Enzymes fit into their substrates like a key fits into a lock (lock-and-key model)
Another model is the induced fit model where the enzyme changes shape slightly upon binding with substrate
Enzymes participate in reactions by joining with substrates
The enzyme and substrate form an enzyme-substrate complex
Enzyme action takes place within the complex
The resulting products separate from the enzyme, leaving the enzyme unchanged and reusable

Enzyme Factors

Enzymes are sensitive to factors such as pH and temperature
Each enzyme has a specific pH range in which it works optimally (e.g., pepsin in the stomach works best at a low pH, amylase in the mouth works best at a neutral pH)
Each enzyme has an optimal temperature range, above which the enzyme's shape changes (denatures) and it loses its activity.
The rate of enzyme activity increases as both the enzyme and substrate concentration increase up until a certain point. Above that point, if there’s excess enzyme, or substrate, the rate won’t increase further.

Denaturation

Extreme temperatures or pH changes cause enzymes to denature
Denaturation changes the enzyme's shape
As a result, the enzyme can no longer bind with its substrate
The enzyme can no longer perform its catalytic function.

Coenzymes and Cofactors

Coenzymes are organic molecules that aid enzymes
Organic molecules typically include vitamins
Cofactors are inorganic molecules that assist enzymes
Inorganic molecules typically include metal ions such as iron

Summary Questions

Enzymes are proteins.
Enzyme action is similar to a key fitting into a lock.
The active site is the binding site on the enzyme.
Substrates are the molecules the enzyme acts on.
pH and temperature affect enzyme function.

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Description

Test your knowledge on enzymes, the biological catalysts that speed up chemical reactions in living organisms. This quiz covers enzyme structure, function, and the mechanisms by which they operate. Dive into the fascinating world of biochemistry and discover how enzymes are essential for life.