The “rungs” of the DNA molecule are made of pairs of nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G).

Quick Scoop: DNA’s Ladder Rungs

  • DNA looks like a twisted ladder, called a double helix.
  • The sides of the ladder are sugar–phosphate backbones (deoxyribose sugar plus phosphate).
  • The rungs of the ladder are base pairs:
    • Adenine (A) always pairs with thymine (T).
* Guanine (G) always pairs with cytosine (C).

These bases pair via hydrogen bonds, forming each step, or “rung,” across the two strands of DNA.

So, if someone asks “what makes up the ‘rungs’ of the DNA molecule?”, the precise answer is: the rungs are pairs of nitrogenous bases (A–T and G–C). 🧬

Information gathered from public forums or data available on the internet and portrayed here.