Lecture 23

What is the primary function of enzymes?

To serve as structural components
To act as catalysts in biochemical reactions (correct)
To provide energy for metabolic processes
To transport molecules across membranes

What is a co-factor?

A type of enzyme
A small molecule required for enzyme activity (correct)
A substrate for biochemical reactions
A product of enzymatic reactions

Which of the following is an example of an inorganic co-factor?

NAD
Vitamin C
Zinc (correct)
Coenzyme A

What is the term for an enzyme without its co-factor?

Apoenzyme (B) Signup and view all the answers

What does the term "turnover number" (kcat) refer to?

The rate at which substrate is converted to product (B) Signup and view all the answers

Which of the following factors can affect the catalytic constant of an enzyme?

Temperature and pH (A) Signup and view all the answers

The "lock and key" model of enzyme action was proposed by which scientist?

Emil Fischer (A) Signup and view all the answers

What does the induced fit model propose about enzyme-substrate interaction?

The substrate causes the active site to change shape upon binding. (B) Signup and view all the answers

What type of interactions stabilize the enzyme-substrate (ES) complex?

Non-covalent interactions (C) Signup and view all the answers

Which of the following is NOT a basic principle of enzyme catalysis?

Oxidative phosphorylation (D) Signup and view all the answers

What role do metal ions play in enzyme function?

They can serve as co-factors that facilitate reactions. (B) Signup and view all the answers

What type of enzyme is chymotrypsin?

Hydrolase (B) Signup and view all the answers

Which enzyme cleaves peptide bonds at the C-terminal side of aromatic amino acids?

Chymotrypsin (D) Signup and view all the answers

Which of the following statements is true regarding enzyme specificity?

Some enzymes can differentiate between isomers. (B) Signup and view all the answers

What does the term "active site" refer to in an enzyme?

The part of the enzyme that binds the substrate (B) Signup and view all the answers

What type of catalysis involves a molecule other than water acting as a proton donor or acceptor?

General acid-base catalysis (B) Signup and view all the answers

Which enzyme is involved in the conversion of fibrinogen to fibrin in blood coagulation?

Thrombin (C) Signup and view all the answers

Which of the following enzymes would function best in an acidic environment?

Pepsin (B) Signup and view all the answers

How does temperature affect enzyme activity?

Enzymes have an optimal temperature range. (C) Signup and view all the answers

What is the effect of a high concentration of substrate on enzyme activity, according to the Michaelis-Menten model?

It eventually reaches a maximum velocity (Vmax). (C) Signup and view all the answers

In the induced fit model, what happens when the substrate binds to the enzyme?

The enzyme undergoes a conformational change. (C) Signup and view all the answers

Which of the following best describes the role of chymotrypsin in digestion?

It hydrolyzes peptide bonds. (B) Signup and view all the answers

What does the term "catalysis by approximation" mean?

The enzyme brings substrates close together to facilitate a reaction. (B) Signup and view all the answers

Which method is commonly used to measure enzyme activity?

Spectrophotometry (A) Signup and view all the answers

What is the significance of weak non-covalent interactions in the enzyme-substrate complex?

They stabilize the transition state. (B) Signup and view all the answers

Which of the following is a characteristic of enzymes?

They are highly specific for their substrates. (C) Signup and view all the answers

What is the function of trypsin in the digestive system?

It cleaves proteins at the carboxyl side of basic amino acids. (B) Signup and view all the answers

Lecture 23 – Enzymes

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