Structure And Properties Of Peptides(Biochemistry ) Questions and Answers

Question 1. Hydrogen bonds in a-helices are
  1.    more numerous than Vander Waals interactions
  2.    roughly parallel to the helix axis
  3.    not present at Phe residues
  4.    analogous to the steps in a spiral staircase
Explanation:-
Answer: Option B. -> roughly parallel to the helix axis
Question 2. The molecular formula for glycine is C2H5O2N. What would be the molecular formula for a linear oligomer made by linking ten glycine molecules together by condensation synthesis?
  1.    C20H32O11N10
  2.    C20H68O29N10
  3.    C20H50O20N10
  4.    C20H40O10N10
Explanation:-
Answer: Option A. -> C20H32O11N10
Question 3. The peptide, Val-Lys-Glu-Met-Ser-Trp-Arg-Ala, was digested with cyanogen bromide (CNBr) to produce:
  1.    Val-Lys-Glu-Met + Ser-Trp-Arg-Ala
  2.    Val-Lys + Glu-Met-Ser + Trp-Arg-Ala
  3.    Val-Lys-Glu + Met-Ser-Trp-Arg-Ala
  4.    Val-Lys-Glu-Met-Ser-Trp + Arg-Ala
Explanation:-
Answer: Option A. -> Val-Lys-Glu-Met + Ser-Trp-Arg-Ala
Question 4. The peptide bond in proteins is
  1.    usually trans unless proline is the next amino acid
  2.    only found between proline residues
  3.    usually cis unless proline is the next amino acid
  4.    is planar because of steric hinderance
Explanation:-
Answer: Option A. -> usually trans unless proline is the next amino acid
Question 5. Which of the following is an example of tertiary structure in a protein?
  1.    An a-helix
  2.    A multimeric protein
  3.    A globular domain
  4.    A P-pleated sheet
Explanation:-
Answer: Option C. -> A globular domain
Question 6. In deoxy hemoglobin (Hb), the Fe (II) is coordinated to
  1.    four nitrogens of heme and to a water molecule
  2.    four nitrogens of heme, the proximal His, and a water molecule
  3.    two nitrogens of heme and to three water molecules
  4.    two nitrogens of heme and to three His residues in Hb
Explanation:-
Answer: Option B. -> four nitrogens of heme, the proximal His, and a water molecule
Question 7. The Ramachandran Plot illustrates the fact that
  1.    the peptide bond is planar
  2.    the F & Y angles can assume approximately three different values
  3.    the F & Y angles can assume only a single value in a protein
  4.    the F & Y angles can assume any value in a peptide
Explanation:-
Answer: Option B. -> the F & Y angles can assume approximately three different values
Question 8. The major element of secondary structure in myoglobin and hemoglobin is
  1.    All of these
  2.    the a-helix
  3.    the P-strand
  4.    the reverse turn
Explanation:-
Answer: Option B. -> the a-helix
Question 9. The resonance structures that can be drawn for the peptide bond indicate that the peptide bond
  1.    has partial double bond character
  2.    both (a) and (b)
  3.    is still not completely understood
  4.    is stronger than an ordinary single bond
Explanation:-
Answer: Option B. -> both (a) and (b)
Question 10. In the β-pleated sheet
  1.    the polypeptide chain is fully extended
  2.    adjacent polypeptide chains can either be parallel or antiparallel
  3.    hydrogen bonds are formed between the peptide bonds
  4.    All of these
Explanation:-
Answer: Option D. -> All of these
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