Question 1

Which of the following best describes the general structure of an alpha amino acid used in protein synthesis?

Accepted Answer

A central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a variable R group.

Question 2

At physiological pH ($$\approx 7$$), what is the net charge of the side chain of glutamic acid?

Accepted Answer

$$-1$$

Question 3

Which amino acid is most likely to form a disulphide bond, stabilizing protein structure?

Accepted Answer

Cysteine

Question 4

A mutation replaces a hydrophobic amino acid buried in a protein core with a hydrophilic one. What is the most likely consequence?

Accepted Answer

The protein may misfold or lose function.

Question 5

Which of the following amino acids is basic and carries a $$+1$$ charge at neutral pH?

Accepted Answer

Arginine

Question 6

What type of bond is formed between the carboxyl group of one amino acid and the amino group of another during polypeptide synthesis?

Accepted Answer

Peptide bond

Question 7

Which property of histidine makes it especially useful in enzyme active sites?

Accepted Answer

It can be both protonated and unprotonated near physiological pH due to its side chain pKa.

Question 8

Using the CORN rule, which configuration do naturally occurring amino acids in proteins have?

Accepted Answer

L-configuration

Question 9

Which of the following is true about the pKa of the alpha amino group in amino acids?

Accepted Answer

It is typically between $$8.8$$ and $$9.7.$$

Question 10

Which amino acid side chain is most likely to participate in hydrogen bonding with water molecules on the protein surface?

Accepted Answer

Serine

Question 11

A patient is treated with a drug that only works if a specific amino acid in a protein is mutated. What does this illustrate about the importance of amino acid sequence?

Accepted Answer

A single amino acid change can dramatically alter protein function and disease outcome.

Question 12

Which of the following best explains why proteins must adopt the correct 3D shape?

Accepted Answer

To perform their specific cellular functions such as catalysis, binding, and movement.

Question 13

Which amino acid is most likely to be found on the surface of a protein interacting with the aqueous environment?

Accepted Answer

Serine

Question 14

What is the main role of ionic bonds between amino acid side chains in proteins?

Accepted Answer

To stabilize the folded structure of proteins.

Question 15

Which of the following amino acids is hydrophobic and typically buried in the protein core?

Accepted Answer

Valine

Question 16

Which statement about the pKa of amino acid side chains is most accurate?

Accepted Answer

If the pKa is close to physiological pH ($$\approx 7$$), the side chain can be protonated or deprotonated in cells.

Question 17

Which amino acid is most likely to participate in catalysis due to its ability to switch between charged and uncharged states at physiological pH?

Accepted Answer

Histidine

Question 18

What is the consequence of a single amino acid mutation in a protein sequence?

Accepted Answer

It can render the protein non-functional and lead to diseases such as cancer or neurodegenerative disorders.

Question 19

Which of the following is NOT a function carried out by proteins in cells?

Accepted Answer

Genetic information storage

Question 20

Which of the following best describes a zwitterion?

Accepted Answer

A molecule with both positive and negative charges, resulting in a net neutral charge.

Amino Acids, Peptides, and Proteins – Structure, Properties, and Stereochemistry

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