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Biochemistry

biomolecules

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Questions

Question 1 Multiple Choice (Single Answer)

Which of the following features are associated with cysteine amino acid?

  1. A. Aliphatic, B. 2 methyl groups and C. Sulphur atom
  2. A. Aliphatic, B. 3 methyl groups and C. Carboxylic acid functional group
  3. A. Aliphatic, B. 2 methyl groups and C. Hydroxyl functional group
  4. A. Aromatic, B. 2 methyl groups and C. Hydroxyl functional group
  5. A. Aliphatic, B. 5 methyl groups and C. No functional group
Question 2 Multiple Choice (Single Answer)

Which of the following amino acids have these given features?
a. It has got an aliphatic carbon chain.
b. It has sulphur atom.
c. It has 5 carbon.
d. It has 1 nitrogen atom in its structure.

  1. Methionine
  2. Histidine
  3. Tryptophan
  4. Proline
  5. Threonine
Question 3 Multiple Choice (Single Answer)

Which of the following Posttranslational Modifications (PTM) leads to highest increase in molecular weight?

  1. Phosphorylation
  2. Hydroxylation
  3. Myristylation
  4. Glycosylation
  5. Acetylation
Question 4 Multiple Choice (Single Answer)

Which of the following atoms is replaced by selenium in cysteine amino acid to form selenocysteine?

  1. Sulphur
  2. Nitrogen
  3. Oxygen
  4. Phosphorus
  5. Chlorine
Question 5 Multiple Choice (Single Answer)

The imidazole group of amino acid A and the guanidino group of amino acid B exist as resonance hybrids with positive charge distributed between both nitrogens in form A or all three nitrogens in form B. Write the names of the amino acids A and B.

  1. A. Histidine, B. Asparagine
  2. A. Asparagine, B. Histidine
  3. A. Valine, B. Asparagine
  4. A. Valine, B. Alanine
  5. A. Leucine, B. Isoleucine
Question 6 Multiple Choice (Single Answer)

Given: pK1 = 2.0, pK2 = 9.9 and pK3 = 3.9
From the information, calculate the isoelectric pH (pI) of Aspartic acid.

  1. 2.95
  2. 15.8
  3. 7.9
  4. 19.8
  5. 11.9
Question 7 Multiple Choice (Single Answer)

Given: pK1 (alpha-COOH) = 2.4 and pK2 (alpha-NH2+) = 9.8
From the information, calculate the isoelectric pH (pI) of Glycine.

  1. 2.4
  2. 9.8
  3. 6.1
  4. 7.4
  5. 23.52
Question 8 Multiple Choice (Single Answer)

Which of the following statements is/are correct?

  1. Both L-amino acids and D-amino acids occur in nature.
  2. Only D-alpha-amino acids are present in proteins.
  3. All amino acids possess at least two weakly acidic functional groups, R-NH3+ and R-COOH.
  4. Amino acids do not possess any type of additional weakly acidic functional groups.
  1. None of these
  2. Only 1
  3. Only 3
  4. Only 2 and 4
  5. All of these
Question 9 Multiple Choice (Single Answer)

Which of the following statements is/are correct?

  1. The pKa values of all functional groups of an amino acid dictate its net molecular at a given pH.
  2. pI is the pH at which an amino acid bears only negative charge and thus moves towards cathode in applied electrical field.
  3. Of the biochemical reactions of amino acids, the most important is the formation of peptide bonds.
  1. None of these
  2. Only I
  3. Only 2
  4. Only 3
  5. Only 1 and 3
Question 10 Multiple Choice (Single Answer)

What is the expected order of bond energy of the following bong types?
O-O, S-S, C-N, S-H, C=C, C=N, C=O

  1. O-O < S-S < C-N < S-H < C=C = C=N < C=O
  2. S-S < O-O < C-N < S-H < C=C = C=O < C=N
  3. C-N < S-S < O-O< S-H < C=C < C=N = C=O
  4. S-S < O-O < C-N < S-H < C=C < C=N < C=O
  5. O-O < S-S < C-N < S-H < C=N < C=C < C=O
Question 11 Multiple Choice (Single Answer)

Which of the following statements is/are correct?

  1. Amino acids are classified based on the properties of their R groups.
  2. Peptides are named for the number of amino acid residues present, and as derivatives of the carboxyl terminal residue.
  3. The partial double-bond character of the bond restricts the number of possible peptide conformations.
  1. Only I
  2. Only II
  3. Only III
  4. All of these
  5. None of these
Question 12 Multiple Choice (Single Answer)

Which of the following statements is/are correct about stationary phase in column chromatography?
1. In column chromatography of proteins, cellulose is used as stationary phase.
2. The stationary phase is packed in a metallic column.
3. The stationary phase matrices interaction is hydrophobic.

  1. Only 1 and 2
  2. Only 2 and 3
  3. Only 1 and 3
  4. All of these
  5. None of these
Question 13 Multiple Choice (Single Answer)

Which is correct regarding partition chromatography?
1. Association between each protein and the matrix is very strong.
2. Proteins that interact more strongly with the stationary phase are retained longer.
3. The time of protein association with the stationary phase depend only on mobile phases.

  1. Only 1
  2. Only 2
  3. Only 3
  4. 2 and 3
  5. 1 and 3
Question 14 Multiple Choice (Single Answer)

Which of the following amino acids have 5 methyl groups, no functional group and no aromatic chain?

  1. Isoleucine
  2. Histidine
  3. Phenylalanine
  4. Tyrosine
  5. Tryptophan
Question 15 Multiple Choice (Single Answer)

On the basis of this fact, what is the correct decreasing order of the pKa range of various dissociating groups?

The acid strengths of weak acids are expressed as their pKa. The net charge on an amino acid is the algebraic sum of all the positively and negatively charged groups present.

  1. Guanidinium of Arg > α - Amino > OH of Tyr > Imidazole of Histidine > α - Carboxyl
  2. Guanidinium of Arg > α - Amino > α - Carboxyl > Imidazole of Histidine > OH of Tyr
  3. Guanidinium of Arg > Imidazole of Histidine > OH of Tyr > α - Amino > α - Carboxyl
  4. Guanidinium of Arg > α-Amino > α - Carboxyl > OH of Tyr > Imidazole of Histidine
  5. Guanidinium of Arg > Imidazole of Histidine > α - Amino > OH of Tyr > α - Carboxyl
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