Question 1

Which level of protein structure is primarily responsible for the sequence of amino acids in a polypeptide chain?

Accepted Answer

Primary structure

Question 2

What type of interaction is most important in stabilizing the tertiary structure of a protein?

Accepted Answer

Ionic and hydrophobic interactions among side chains

Question 3

Which amino acid can form an ion pair with glutamic acid at pH 7?

Accepted Answer

Arginine

Question 4

Enzymes speed up chemical reactions by:

Accepted Answer

Lowering the activation energy required for the reaction

Question 5

Which equation best represents the effect of an enzyme on activation energy ($$E_a) $$for a reaction?

Accepted Answer

$$E_{a,enzyme} \u003c E_{a,uncatalyzed}$$

Question 6

A patient’s blood contains an enzyme that converts CO$$_2$$ and H$$_2O $$into HCO$$_3^-$$ and H$$^+. $$What is the role of this enzyme in the body?

Accepted Answer

It speeds up the conversion, helping regulate blood pH

Question 7

Which enzyme classification catalyzes the transfer of a functional group from one molecule to another?

Accepted Answer

Transferases

Question 8

During the hydrolysis of sucrose by sucrase, which type of enzyme is sucrase?

Accepted Answer

Hydrolase

Question 9

What happens to an enzyme when it is denatured by heat?

Accepted Answer

Its secondary and tertiary structures are disrupted

Question 10

Which of the following best describes the specificity of an enzyme’s active site?

Accepted Answer

It binds only substrates with a complementary 3D shape and chemical properties

Question 11

A mutation changes a hydrophobic amino acid in the active site of an enzyme to a hydrophilic one. What is the most likely effect?

Accepted Answer

The enzyme’s substrate specificity may decrease

Question 12

Which of the following is an example of negative allosteric regulation?

Accepted Answer

A product binds to the enzyme’s allosteric site, reducing its activity

Question 13

If the optimum temperature for an enzyme is 37°C, what happens to the reaction rate at 60°C?

Accepted Answer

It decreases due to denaturation

Question 14

Which of the following best explains why enzymes are effective in biological systems?

Accepted Answer

They lower the activation energy, allowing reactions to occur rapidly at body temperature

Question 15

Which of the following is NOT a way to denature a protein?

Accepted Answer

Adding a substrate

Question 16

A patient is exposed to a heavy metal that binds to the active site of an enzyme. What is the most likely outcome?

Accepted Answer

The enzyme will be denatured and lose its function

Question 17

Which of the following statements about quaternary structure is correct?

Accepted Answer

It involves the interaction of two or more polypeptide chains

Question 18

Which enzyme classification catalyzes the joining of two molecules using ATP?

Accepted Answer

Ligase

Question 19

A metabolic pathway is regulated by feedback inhibition. Which molecule typically acts as the inhibitor?

Accepted Answer

The end product of the pathway

Question 20

Which of the following best describes the role of pH in enzyme activity?

Accepted Answer

Each enzyme has an optimum pH, and deviation can lead to denaturation

CH 19+20 STUDY NOTES

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