This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Nucleic Acid Structure”.
1. Number of hydrogen bonds between adenine and thymine?
Explanation: A = T is the notation for bonding between A and T.
2. Number of hydrogen bonds between guanine and cytosine?
Explanation: G≡C is the notation for bonding between G and C.
3. Which ratio is constant for DNA?
a) A + G / T + C
b) A + T / G + C
c) A + C / U + G
d) A + U / G + C
Explanation: The molar concentration of purine bases A and G is equal to the molar concentration of pyrimidine bases T and C because one of each type makes up a base pair. Because of base pairing rules, A = T and G = C. The specific A – T and G – C content varies from species to species. But in any one species the ratio is constant.
4. According to Chargaff’s rule, in a DNA molecule ____________
a) The amount of adenine and thymine is equal to the amount of guanine and cytosine
b) The amount of adenine and guanine is equal to the amount of thymine and cytosine
c) The amount of adenine and uracil is equal to the amount of guanine and cytosine
d) The amount of adenine and guanine is equal to the amount of uracil and cytosine
Explanation: According to Chargaff’s rule, whatever the amount of adenine, it is equal to the amount of thymine and same is the case with guanine and cytosine.
5. Arrangement of nucleotides in DNA can be seen by ____________
b) X-Ray crystallography
c) Light microscope
d) Electron microscope
Explanation: It is a scientific method used to determine the arrangement of atoms of a crystalline solid in a three dimensional space.
6. Which of the following leads to disruption of nucleosomal structure?
Explanation: Methylation denatures nucleosomal structure.
7. Which one of the following nucleic acids has a left handed helix?
Explanation: Z-DNA is left handed and B-DNA is right handed helix.
8. Which of the following statements is not true about RNA?
a) Does not have a double stranded structure
b) Thymine is present
c) Does not obey Chargaff’s rule
d) The sugar contained in RNA is a ribose
Explanation: Thymine is present in DNA.
9. Which of the following is true about Z-DNA helix?
a) It has alternating GC sequences
b) It is a permanent conformation of DNA
c) It tends to be found at the 3’ end of the genes
d) It has fewer base pairs per turn than B-DNA
Explanation: It is a temporary conformation of DNA
It has more base pairs per turn than B-DNA.
10. Which of the following statements is true?
a) The template strand matches the sequence of the RNA transcript
b) The two strands of DNA run parallel to each other
c) G-C bonds are much more resistant to denaturation than A-T rich regions
d) The common form of DNA is left handed
Explanation: The two strands of DNA run antiparallel to each other.
The common form of DNA is B-DNA which is right handed.
Sanfoundry Global Education & Learning Series – Biochemistry.
To practice all areas of Biochemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.