This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Protein Sequences and Evolution”.
1. Amino acids sequence in DNA can be determined by the order of their
Explanation: By the order of nucleotides, amino acids sequence in DNA can be determined.
2. Which of the following is a Sanger’s reagent?
a) 1-fluoro-2, 4-dinitrobenzene
b) 1-fluoro-2, 3-dinitrobenzene
c) 1-fluoro-2, 4-trinitrobenzene
d) 1-fluoro-2, 3-trinitrobenzene
Explanation: To identify the amino-terminal amino acid residue, Sanger developed the reagent 1-fluoro-2, 4-dinitrobenzene (FDNB).
3. The amino acid sequences of thousands of different proteins from many species have been determined using principles first developed by
d) Watson and Crick
Explanation: The amino acid sequences of thousands of different proteins from many species have been determined using principles first developed by Frederick Sanger.
4. Which of the following compound is not involved in Edman degradation?
b) CF3 COOH
Explanation: FDNB is involved in Sanger’s method.
5. Which of the following statements is false?
a) Oxidation of cysteine residue with performic acid is done to break disulfide bond in proteins
b) Reduction of cysteine residue with dithiothreitol is done to break disulfide bond in proteins
c) Reduction of cysteine residue with performic acid is done to break disulfide bond in proteins
d) Reduced cysteine is further acetylated by iodoacetate
Explanation: Oxidation of cysteine residue with performic acid is done to break disulfide bond in proteins.
6. Cleaving of peptide chain is done by
Explanation: Trypsin is a digestive enzyme that fragments polypeptide chain.
7. Which of the following is the correct order of sequencing?
a) Cleaving, sequencing and ordering
b) Sequencing, ordering and cleaving
c) Ordering, cleaving and sequencing
d) Ordering, sequencing and cleaving
Explanation: First fragmenting of a peptide is done followed by sequencing and ordering the peptide fragments.
8. Edman degradation is used for
a) Identifying N-terminal amino acids
d) Identifying C-terminal amino acids
c) Identifying amino acid
d) Identifying carbohydrates
Explanation: Edman degradation is used for identifying N-terminal amino acids.
9. What best summarizes the MALDI method by which gas phase ions are produced for mass spectrometry?
a. Sample is hit by a low energy xenon beam.
b. Sample is forced through a narrow capillary tube and solvent rapidly evaporates.
c. Sample is embedded in a crystalline matrix and bombarded by laser beams.
d. Sample is heated and then bombarded by electrons
Explanation: MALDI, the term itself is an abbreviation for Matrix Assisted Laser Desorption or Ionization.
10. Which of the following is Edman reagent?
b) CF3 COOH
Explanation: The Edman reagent, phenylisothiocyanate reacts with the amine group of the N-terminal amino acid.
Sanfoundry Global Education & Learning Series – Biochemistry.
To practice all areas of Biochemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.