Enzymes, cofactors and coenzymes

Which of the following statements regarding enzyme is TRUE

• Enzyme decreases the free energy change of a reaction

• Enzyme changes the direction of chemical reaction

• Enzyme increase rate of reaction

• Enzyme prevents changes in substrate concentration

Tags

NGSS.HS-PS1-5

An enzyme catalyses a reaction by …

• lowering the energy of activation of a reaction

• supplying the energy to speed up a reaction.

• lowering the free energy of a reaction.

• changing the equilibrium of a spontaneous reaction.

Tags

NGSS.HS-PS1-4

What is the active site of an enzyme?

• A region that binds allosteric regulators of the enzyme

• A region that binds the products of the catalytic reaction

• A region that is inhibited by the presence of a coenzyme or a cofactor

• A region that is involved in the catalytic reaction of the enzyme

Zinc, an essential trace element for most organisms, is present in the active site of enzyme carboxypeptidase. The zinc most likely functions as

• a cofactor necessary for enzyme activity

• a competitive inhibitor of the enzyme

• a non-competitive inhibitor of the enzyme

• a coenzyme derived from a vitamin

Watch the animation and identify the hypothesis involved

• Lock and Key hypothesis

• Induced Fit hypothesis

• Enzyme-Substrate hypothesis

NAD⁺ is the example of

• metal ion activator

• coenzyme

• prosthetic group

What reduces the productivity of enzymes by preventing substrates from entering active sites?

• non competitive inhibitors

• competitive inhibitors

• coenzymes

• cofactors

According to the induced fit hypothesis of enzyme catalysis, which of the following is CORRECT?

• The binding of the substrate slightly changes the shape of the enzyme’s active site

• The binding of the substrate depends on the shape of the active site

• Some enzymes change their structure when activators bind to the enzyme

• A competitive inhibitor can outcompete the substrate for the active site

A series of enzymes catalyze the reaction A --> B --> C --> D. Product D binds to the enzyme that converts A to B at a position other than its active site. This binding decreases the activity of the enzyme. What is substance A?

• A substrate

• A coenzyme

• The product

• An allosteric inhibitor

Which of these are NOT characteristics of an enzyme.?

• Enzymes are highly specific

• Can be denatured at high pH

• Reusable

• Can be denatured at extreme pH