Biochemistry: Enzymes and Their Functions

Questions and Answers

What is the primary function of enzymes in the body?

To slow down chemical reactions

To expedite chemical reactions (correct)

To change the energy levels of reactions

To act as substrates for reactions

What do we call the model that describes how a substrate fits into an enzyme's active site like a key into a lock?

The Induced Fit Model

The Enzyme-Substrate Model

The Lock and Key Model (correct)

The Catalytic Model

Which stage occurs after the enzyme-substrate complex forms?

The substrate is released unchanged

The products are produced (correct)

The reaction slows down

The enzyme is recycled

What type of molecules can serve as cofactors for enzymes?

Both organic and inorganic molecules Signup and view all the answers

What happens to an enzyme after it catalyzes a reaction?

It is recovered unchanged Signup and view all the answers

Which model states that the binding of a substrate induces a change in the active site of the enzyme?

The Induced Fit Model Signup and view all the answers

What is the name given to the complex formed when the enzyme and substrate bind?

Enzyme-Substrate Complex Signup and view all the answers

What is a shared characteristic of enzymes?

They are very specific to certain reactions Signup and view all the answers

What suffix is commonly added to the name of an enzyme based on its substrate?

-ase Signup and view all the answers

Which of the following factors does not influence enzyme action?

Presence of spirits Signup and view all the answers

What is the correct order for the enzyme classification system?

Enzyme class, Subclass, Sub-sub class, Particular enzyme Signup and view all the answers

Which of the following enzymes is responsible for breaking down proteins?

Protease Signup and view all the answers

Which of the following represents the sub-sub class 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

Study Notes

Importance of Enzymes

Enzymes are complex organic compounds crucial for speeding up chemical reactions in the body without changing themselves.
Specificity is a key feature; each enzyme catalyzes one specific chemical reaction, enhancing reaction rates significantly.

Structure and Function

Enzymes consist of active sites, where substrates bind, forming an enzyme-substrate complex.
The reaction proceeds, transforming substrates into products, which are then released while the enzyme remains unchanged.

Models of Enzyme Action

Lock and Key Model: Proposed by Emil Fischer, suggesting a rigid fit between substrate and enzyme, like a key in a lock.
Induced Fit Model: Proposed by Daniel E. Koshland Jr., indicating that substrate binding induces conformational changes in the enzyme, facilitating the reaction.

Coenzymes and Cofactors

Coenzymes are organic molecules that assist enzymes and bind loosely to them.
Cofactors can be inorganic or organic and assist in substrate recruitment without permanent binding.

Enzyme Nomenclature

Enzyme names often end in -ase, derived from either the substrate (e.g., lactase from lactose) or the type of reaction (e.g., oxidase).
The systematic nomenclature includes the EC number, indicating enzyme class, subclass, and specific enzyme identity.

Biological Enzyme Examples

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

Factors Influencing Enzyme Action

Concentration of substrates and enzymes affect reaction rates.
Temperature and pH levels can optimize or hinder enzyme effectiveness.
Presence of accelerators can enhance enzyme action, while inhibitors can slow it down or stop it.
Environmental hazards may negatively impact enzyme function.