DNA Structure MCQs | DNA Structure Multiple Choice Questions and Answers

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Questions
1 In a DNA double helix the bases are held together by hydrogen bonds. These hydrogen bonds are _________
A Ionic bonds
B Covalent bonds
C Non-covalent bonds
D Van der Waals forces

Answer: Non-covalent bonds
2 With respect to the importance of hydrogen bonding and DNA double helix stability, which of the following statements is false?
A Decreases the entropy
B Contributes to the thermodynamic stability
C Favorable tautomeric form of nucleotide bases
D Specificity of base pairing

Answer: Decreases the entropy
3 Levene investigated and found that the nucleic acid is composed of poly-nucleotides and each nucleotide is composed of one base, a sugar molecule and a phosphate. This was performed on the genome of________________
A Yeast
B Bacteria
C Fungi
D WBCs

Answer: Yeast
4 A nucleoside is composed of
A a base+ a sugar+ phosphate
B a base+ a phosphate
C a base+ a sugar
D none of these

Answer: a base+ a sugar
5 DNA is the genetic material in
A prokaryote and eukaryote
B viruses, prokaryote and eukaryote
C in some viruses, prokaryotes and eukaryotes
D only in eukaryotes

Answer: in some viruses, prokaryotes and eukaryotes
6 Chromatin is composed of
A Proteins Only
B Nucleic Acids Only
C Nucleic Acids And Protein
D None Of These

Answer: Nucleic Acids And Protein
7 Adjacent nucleotides are joined by
A Phosphodiester Bond
B Covalent Bond
C Ionic Bond
D none of the above

Answer: Phosphodiester Bond
8 The type of sugar in DNA are
A Hexose
B Pentose
C Tetrose
D Triose

Answer: Pentose
9 The length of DNA having 23 base pairs is
A 74.8 Ao
B 78 Ao
C 78.4 Ao
D 78.2 Ao

Answer: 74.8 Ao
10 Which of the following statements is incorrect about t RNA species?
A All t RNAs have between 10-20 nucleotides
B They make up 15% of the t RNA in the cell
C They have the smallest size of the three major species
D There is at least one specific t RNA molecule for each of the 20 amino acids

Answer: All t RNAs have between 10-20 nucleotides
11 When the B DNA is slightly dehydrated in the laboratory it takes on-
A A conformation
B Negative supercoils
C Positive supercoils
D Z conformation

Answer: A conformation
12 Which of the following nucleic acids has a left-handed helix?
A A-DNA
B B DNA
C m-RNA
D Z-DNA

Answer: Z-DNA
13 Which of the following processes would not lead to disruption of the nucleosomal structure?
A Carboxylation
B Acetylation
C Methylation
D None Of The Above

Answer: Methylation
14 Choose the incorrect statement about histones
A H2A and H2B form dimers
B H3 and H4 form a tetramer
C H2A, H2B, H3, and H4 form the core of a nucleosome
D H1 histones are tightly bound to chromatin

Answer: H1 histones are tightly bound to chromatin
15 Which of the following has the highest percentage of modified bases ?
A t-RNA
B hn RNA
C sn RNA
D m-RNA

Answer: t-RNA
16 Choose the incorrect statement about an RNA:
A Has a single stranded structure
B Instead of Uracil contains the ribonucleotides of thymine
C Does not obey Chargaff’s rule
D Does not exhibit Watson and crick’s base pairing

Answer: Instead of Uracil contains the ribonucleotides of thymine
17 An endonuclease is an enzyme that hydrolyzes:
A A phosphodiester bond located in the interior of a polynucleotide
B A nucleotide from only the 3’ end of an oligonucleotide
C A nucleotide from either terminal of an oligonucleotide
D A bond only in the specific sequence of nucleotides

Answer: A phosphodiester bond located in the interior of a polynucleotide
18 Which of the following RNAs contains both a 7-Methyl guanosine triphosphate cap and polyadenylate segment?
A m-RNA
B hn RNA
C t-RNA
D None of the above

Answer: m-RNA
19 The first X-ray diffraction patterns of DNA were taken in 1938 by ___________
A Rosalind Franklin
B Francis H. Crick
C William Asbury
D none of the above

Answer: William Asbury
20 In early 1950s high quality X-ray diffraction photographs of DNA suggesting the DNA being double helix and composed of two nucleotide strands. Who took those photographs?
A Rosalind Franklin and Maurice Wilkins
B Rosalind Franklin
C William Asbury
D Francis H. Crick and James D. Watson

Answer: Rosalind Franklin and Maurice Wilkins
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