Question

? question cluster
part a: multiple-choice questions

1. the overall structure of dna is described as a double helix. the

ungs\ of this structure,
which contain the genetic code, are formed by:
(1) alternating deoxyribose sugars and phosphate groups
(2) nitrogenous bases paired specifically by hydrogen bonds
(3) the single-stranded rna molecule during transcription
(4) amino acid chains linked by peptide bonds
according to the

Explanation:

To solve this, we analyze each option:

• Option (1): Alternating deoxyribose sugars and phosphate groups form the backbone (sides) of the DNA double helix, not the rungs.
• Option (2): The "rungs" of the DNA double helix are formed by nitrogenous bases (adenine - thymine, guanine - cytosine) paired specifically by hydrogen bonds. This carries the genetic code.
• Option (3): RNA during transcription is related to copying DNA, not the structure of DNA's rungs.
• Option (4): Amino acid chains with peptide bonds are part of proteins, not DNA structure.

Answer:

(2) nitrogenous bases paired specifically by hydrogen bonds