1. Peptide bond is a _________
a) Covalent bond
b) Ionic bond
c) Metallic bond
d) Hydrogen bond
Explanation: Two amino acids are covalently joined through a substituted amide linkage called a peptide bond.
2. A tripeptide has ________
a) 3 amino acids and 1 peptide bond
b) 3 amino acids and 2 peptide bonds
c) 3 amino acids and 3 peptide bonds
d) 3 amino acids and 4 peptide bonds
Explanation: Monopeptide is a peptide containing single amino acid, dipeptide contains two amino acids joined by one peptide bond and tripeptide contains three amino acids joined by two peptide bonds.
3. The factor which does not affect pKa value of an amino acid is _________
a) The loss of charge in the α-carboxyl and α-amino groups
b) The interactions with other peptide R groups
c) Other environmental factors
d) Molecular weight
Explanation: The loss of charge in the α-carboxyl and α-amino groups, the interactions with other peptide R groups and other environmental factors can affect the pKa.
4. Which of the following is a 39-residue hormone of the anterior pituitary gland?
a) Corticotropin
b) Glucagon
c) Insulin
d) Bradykinin
Explanation: Corticotropin is a 39-residue hormone of the anterior pituitary gland that stimulates the adrenal cortex.
5. The average molecular weight of an amino acid residue in a protein is about _________
a) 128
b) 118
c) 110
d) 120
Explanation: The average molecular weight of an amino acid residue is nearer to 128. Because a molecule of water is removed to create each peptide bond, average molecular weight is 128 – 18 = 110.
6. Which of the following is not the classified form of conjugated proteins?
a) Lipoproteins
b) Glycoproteins
c) Metalloproteins
d) Complete proteins
Explanation: On the basis of the chemical nature of their prosthetic groups conjugated proteins are classified into lipoproteins, glycoproteins and metalloproteins.
7. Which part of the amino acid gives it uniqueness?
a) Amino group
b) Carboxyl group
c) Side chain
d) None of the mentioned
Explanation: Different amino acids contain different side chains which make them unique.
8. Which of the following information is responsible to specify the three-dimensional shape of a protein
a) The protein’s peptide bond
b) The protein’s amino acid sequence
c) The protein’s interaction with other polypeptides
d) The protein’s interaction with molecular chaperons
Explanation: The amino acid sequence of a protein determines its three-dimensional shape.
9. Unfolding of a protein can be termed as _________
a) Renaturation
b) Denaturation
c) Oxidation
d) Reduction
Explanation: The proteins lose their quaternary, tertiary, secondary structure and return to its native state by denaturation process.
10. What are the following is not a factor responsible for the denaturation of proteins?
a) pH change
b) Organic solvents
c) Heat
d) Charge
Explanation: pH change, organic solvents and heat are the factors responsible for the denaturation of proteins.