Enzymes and Their Action

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Questions and Answers

Which statement about enzymes is true?

Enzymes are primarily carbohydrates.

All enzymes have a rigid structure.

Most enzymes are proteins. (correct)

Enzymes do not require cofactors.

What distinguishes digestive enzymes from other enzymes?

They are less active at higher pH levels.

They only catalyze reactions involving carbohydrates.

They do not require specific temperatures.

They have names that end with -in. (correct)

At what temperature do most enzymes exhibit optimum activity?

37°C (correct)

25°C

100°C

10°C

What happens to enzyme activity at extremely high temperatures?

Activity is lost due to denaturation. Signup and view all the answers

What is the effect of pH on enzyme activity?

Most enzymes have peak activity at an optimum pH. Signup and view all the answers

Which model describes the enzyme's flexibility in binding to the substrate?

Induced fit model Signup and view all the answers

What occurs when substrate concentration is increased?

The rate stays constant after a point. Signup and view all the answers

Which statement about the active site of an enzyme is correct?

Only substrates with the same shape as the active site can bind. Signup and view all the answers

What happens to the enzyme's shape when a substrate binds according to the induced fit model?

The shape of the enzyme adapts to the shape of the substrate Signup and view all the answers

Which class of enzymes is responsible for transferring a group of atoms from one molecule to another?

Transferases Signup and view all the answers

In competitive inhibition, what is the primary action of the inhibitor?

It occupies the active site, preventing substrate binding Signup and view all the answers

Which of the following statements is true regarding noncompetitive inhibition?

The inhibitor binds to the enzyme but not at the active site Signup and view all the answers

What type of reaction do lyases typically catalyze?

Add/Remove atoms to form double bonds Signup and view all the answers

Which of these conditions would likely decrease the rate of an enzymatic reaction?

Changing pH to an extreme level Signup and view all the answers

What is a characteristic feature of oxidoreductases?

They remove hydrogen from a substrate Signup and view all the answers

Which enzyme classification does not involve the breaking or forming of bonds?

Isomerases Signup and view all the answers

Study Notes

Enzymes

Most enzymes are proteins.
Enzymes contain cofactors: metal ions and vitamins.
Enzyme names typically end with "-ase" (e.g., sucrase, lipase).
Examples of digestive enzymes include pepsin, trypsin, and chymotrypsin.

Enzyme Action

Lock and Key Model: A substrate fits into a specific active site on the enzyme, like a lock and key. Only specific substrates fit. The enzyme-substrate complex forms, and products are released.
Induced Fit Model: The enzyme's active site is flexible. It changes shape to accommodate the substrate, further enhancing the binding.
Factors Affecting Enzyme Activity:
- Temperature: Enzymes have optimal temperatures for activity (typically 37°C). Activity decreases at both higher and lower temperatures due to denaturation or insufficient kinetic energy.
- pH: Enzymes have optimal pH values. Activity decreases significantly above or below these values.
- Substrate Concentration: Increasing substrate concentration increases the reaction rate up to a point where all available enzymes are saturated.

Enzyme Inhibition

Competitive Inhibition: Inhibitors have a similar shape to the substrate, competing for the active site. Increasing substrate concentration can overcome this inhibition.
Noncompetitive Inhibition: Inhibitors bind to a different site (allosteric site) on the enzyme, changing its shape and reducing its activity. Increasing substrate concentration does not overcome this inhibition.

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Description

This quiz explores the fundamentals of enzymes, including their structure, examples, and how they function through the lock and key and induced fit models. It also covers factors influencing enzyme activity such as temperature and pH. Test your knowledge on these essential biological catalysts!