Nucleic acids Knowledge-Based Download PDF

Questions

1. 1.

   In the secondary structure of double-stranded DNA, how many intermolecular hydrogen bonds specifically stabilize the complementary base pair formed between guanine and cytosine?

   • A) Three
   • B) Two
   • C) One
   • D) Four
2. 2.

   Which of the following pairs represents the purine nitrogenous bases found in naturally occurring nucleic acids?

   • A) Cytosine and thymine
   • B) Cytosine and uracil
   • C) Adenine and guanine
   • D) Thymine and adenine
3. 3.

   Which chemical group is bonded to the $2'$ position of the pentose sugar ring in ribonucleic acid (RNA) nucleotides, but is replaced by a hydrogen atom in deoxyribonucleic acid (DNA) nucleotides?

   • A) An amino group ($-\text{NH}_2$)
   • B) A hydroxyl group ($-\text{OH}$)
   • C) A methyl group ($-\text{CH}_3$)
   • D) A carboxyl group ($-\text{COOH}$)
4. 4.

   In a nucleotide monomer of a nucleic acid, to which carbon atom of the pentose sugar is the nitrogenous base covalently linked via an N-glycosidic bond?

   • A) C-5'
   • B) C-3'
   • C) C-2'
   • D) C-1'
5. 5.

   Which type of covalent linkage joins consecutive nucleotide units along the backbone of a nucleic acid chain?

   • A) Peptide bond
   • B) Glycosidic bond
   • C) Phosphodiester bond
   • D) Hydrogen bond