Enzymes BIO 024 Lesson 9

Questions and Answers

What is the main function of an enzyme in the body?

To store energy

To provide structural support

To act as a genetic material

To speed up chemical reactions (correct)

What is the relationship between a substrate and an enzyme?

Substrates change the shape of the enzyme

Enzymes can bind with multiple substrates at once

Enzymes and substrates do not interact

Substrates fit into the active site of enzymes (correct)

In the enzyme action process, what forms after the substrate binds to the enzyme?

Cofactor

Enzyme-substrate complex (correct)

Product

Active site

Which model suggests that the shape of the enzyme and substrate are rigid and fixed?

Lock and Key Model Signup and view all the answers

What occurs during the Induced Fit Model of enzyme action?

The active site adjusts to fit the substrate Signup and view all the answers

What are coenzymes classified as?

Organic molecules that may bind to enzymes Signup and view all the answers

What is the process called when products are released after an enzyme-substrate interaction?

Release Signup and view all the answers

What happens to the enzyme after the reaction takes place?

It is recycled and remains unchanged Signup and view all the answers

How do strong reaction rates typically proceed in the absence of an enzyme?

Reactions may hardly proceed at all Signup and view all the answers

Which of the following statements about enzyme specificity is correct?

Enzymes are highly specific to their substrates Signup and view all the answers

What suffix is commonly added to the name of enzymes to indicate their function?

-ase Signup and view all the answers

In the EC nomenclature system, what does the first digit represent?

Enzyme class Signup and view all the answers

Which enzyme is responsible for breaking down lactose?

Lactase Signup and view all the answers

Which of the following factors does NOT influence enzyme action?

Color of the enzyme Signup and view all the answers

What is the EC number for an enzyme acting on the CH-OH group of donors with NADP+ as an acceptor?

1.1.1.2 Signup and view all the answers

Which enzyme is responsible for the breakdown of fibers?

Cellulase Signup and view all the answers

If an enzyme's activity decreases due to the presence of a substance, what is that substance called?

Inhibitor Signup and view all the answers

Which of the following is an example of a coloring enzyme?

None of the above Signup and view all the answers

Which enzyme catalyzes the breakdown of starch?

Amylase Signup and view all the answers

What is a common method of encoding enzyme functions in the EC system?

Listing numbers in a sequence Signup and view all the answers

Study Notes

Importance and Definition of Enzymes

Enzymes are complex organic compounds crucial for speeding up chemical reactions in the body without being consumed.
They exhibit high specificity, catalyzing only one specific reaction and can be recycled.

Structure of Enzymes

Enzymes interact with substrates at an active site, forming an enzyme-substrate complex.
The substrate can either break down or combine to create products.

Mode of Enzyme Action

Substrate contacts the enzyme's active site, leading to the formation of an enzyme-substrate complex.
After transformation, products are formed and released, allowing the unchanged enzyme to catalyze further reactions.

Enzyme Models

Lock and Key Model: Proposed by Emil Fischer (1894), suggests that the enzyme and substrate fit together like a key in a lock.
Induced Fit Model: Proposed by Daniel E. Koshland Jr. (1958), indicates the substrate induces a conformational change in the enzyme, enhancing binding.

Cofactors and Coenzymes

Cofactors can be organic or inorganic and aid in substrate recruitment; they may bind loosely to enzymes.
Coenzymes are organic molecules that assist enzymes in their functions.

Nomenclature of Enzymes

Enzymes are named by adding the suffix -ase to the substrate (e.g., lactase for lactose) or to the reaction catalyst (e.g., oxidase).
A systematic nomenclature includes an EC (enzyme class) number, with four digits representing class, subclass, sub-subclass, and specific enzyme number.

Examples of Biological Enzymes

Lipase: Breaks down fats.
Protease: Breaks down proteins.
Cellulase: Breaks down cellulose (fiber).
Amylase: Breaks down starch.
Sucrase: Breaks down sucrose.
Maltase: Breaks down maltose.
Lactase: Breaks down lactose.

Factors Influencing Enzyme Action

Substrate concentration affects enzyme activity.
Enzyme concentration, along with temperature and pH, also influences performance.
Presence of accelerators can enhance, while inhibitors can hinder enzyme action.
Environmental hazards can impact enzyme functionality.

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Description

This quiz covers key aspects of enzymes including their definition, importance, structure, and classification. Students will explore how enzymes function in the body and the factors influencing their activities. Understanding these concepts is essential for mastering biological processes.