DNA Double Helix

DNA is made up of two intertwined strands of nucleotides that together form a double helix, a conformation resembling a twisted ladder. As shown, the bases of each nucleotide form the rungs of the ladder, while the sides are composed of alternating sugar and phosphate groups. The sugar-phosphate backbone of the helix is held together by phosphodiester bonds, while adjacent bases pair with one another by hydrogen bonding. Because of the way bases in the DNA molecule are structured and positioned, the ladder configuration twists into a double helix. This complementary structure is ideal for a genetic molecule that must replicate to function.

Question 1: DNA is a double helical structure that is made up of a _________ backbone.
  1. Sugar-phosphate
  2. Base pair
  3. Hydrogen bonded
  4. Ladder

Answer 1

Answer - (a) Sugar-phosphate

Question 2: The backbone of the DNA helix is held together by ___________ bonds while the complimentary base pairs are held together by hydrogen bonds.
  1. Phosphodiester
  2. Peptide
  3. Van der Waals
  4. Electrostatic

Answer 2

Answer - (a) Phosphodiester