DNA structure Original Scenario-Based Download PDF

Questions

1. 1.

   To anchor a metabolic sensor inside an artificial cellular droplet, a molecular architect synthesizes a 300-base-pair double-stranded DNA sequence. Chemical sequencing of the primary strand (Strand Alpha) reveals that 35% of its nucleotides are adenine and 20% are cytosine. The two strands associate spontaneously in a physiological buffer to form a standard B-DNA double helix. Based on the fundamental rules of DNA structure, which statement accurately characterizes the complementary strand (Strand Beta)?

   • A) It runs parallel to Strand Alpha in the 5'-to-3' direction and contains 60 thymine residues.
   • B) It contains 105 uracil residues that stabilize the helix through three hydrogen bonds per pair.
   • C) It contains 60 cytosine residues that pair with adenine via phosphodiester bonds.
   • D) It runs antiparallel to Strand Alpha and contains exactly 105 thymine residues paired with adenine via two hydrogen bonds.