This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Biochemistry Tough Questions and Answers”.
1. Which of the following is not true about secondary protein structure?
a) The hydrophilic/hydrophobic character of amino acid residues is important to secondary structure
b) The ability of peptide bonds to form intramolecular hydrogen bonds is important to secondary structure
c) The alpha helix, beta pleated sheet and beta turns are examples of protein secondary structure
d) The steric influence of amino acid residues is important to secondary structure
View Answer
Explanation: The hydrophilic/hydrophobic character of amino acid residues is important to protein tertiary structure rather than to secondary structure. In secondary structure, it is the steric size of the residues that are important and residues are positioned to minimize interactions between each other and the peptide chain.
2. A structure that has hydrogen bonds between polypeptide chains arranged side by side is ____________
a) Primary structure
b) α-helix
c) β-pleated sheets
d) Tertiary structure
View Answer
Explanation: A structure that has hydrogen bonds between polypeptide chains arranged side by side is β-pleated sheets.
3. The enzyme of E.coli is a nuclease that initiates the repair of double stranded DNA breaks by homologous recombination is?
a) DNA glycosylase
b) DNA ligase
c) DNA polymerase
d) RNA polymerase
View Answer
Explanation: DNA glycosylase catalyzes the first step of base excision repair in DNA.
4. Which of the statements is false about multiple sequence alignment?
a) Both protein and nucleic acid secondary structures can be used
b) More useful in RNA
c) These alignments can be made more accurate by the inclusion of secondary structure information
d) A significant increase in accuracy
View Answer
Explanation: Less useful in RNA. This is because base pairing is highly conserved than sequence.
5. Which of the following serves as a bactericidal agent?
a) Ribonuclease
b) Lysozyme
c) Cytochrome c
d) Myoglobin
View Answer
Explanation: Lysozyme can lyse, or degrade, bacterial cell walls, so it serves as a bactericidal agent.
6. Which of the following enzyme is secreted by the pancreas?
a) Ribonuclease
b) Lysozyme
c) Cytochrome c
d) Myoglobin
View Answer
Explanation: Ribonuclease is secreted by the pancreas into small intestine, where it catalyzes the hydrolysis of certain bonds in ribonucleic acids present in the ingested food.
7. Which of the following statement is false?
a) Lysozyme has S-S linkage
b) Ribonuclease has S-S linkage
c) Heme group in cytochrome c is covalently linked to the protein on two sides
d) Ribonuclease has SH-SH linkage
View Answer
Explanation: Lysozyme and ribonuclease have disulfide linkages.
8. Which of the following is first determined as oligomer?
a) Myoglobin
b) Collagen
c) Keratin
d) Hemoglobin
View Answer
Explanation: Hemoglobin contains four polypeptide chains and four heme prosthetic groups in which iron atoms are present in Fe+2 state.
9. Which of the following is abundantly found in collagen?
a) Glycine
b) Serine
c) Alanine
d) Tryptophan
View Answer
Explanation: Each three amino acids of the collagen peptide chain is a glycine. It is thus an abundant amino acid that is important for collagen structure.
10. Which of the following are important for white blood cell recognition?
a) Glycosaminoglycans
b) Proteoglycans
c) Glycoproteins
d) Glycolipids
View Answer
Explanation: Especially in mammals glycoproteins are essential for white blood cell recognition.
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