Using the terms in the “Ladder” structure of DNA . The sugar phosphates are the beams/supports and the what are the rungs/steps. Amino acids Nucleotide base pairs Genes Chromosomes
The correct answer and explanation is:
Correct Answer: Nucleotide base pairs
Explanation (300 Words):
DNA, or deoxyribonucleic acid, is often described using the “ladder” or double helix structure to help visualize its shape. This structure helps us understand how DNA stores genetic information and how it can be copied during cell division.
In this ladder model:
- The sugar-phosphate backbone forms the sides (or beams/supports) of the ladder. This backbone consists of alternating molecules of deoxyribose sugar and phosphate groups. These give DNA its structural stability.
- The rungs or steps of the ladder are made of nucleotide base pairs. Each rung consists of two nitrogenous bases (Adenine, Thymine, Cytosine, or Guanine) that pair specifically:
- Adenine (A) pairs with Thymine (T)
- Cytosine (C) pairs with Guanine (G)
These base pairs are held together by hydrogen bonds, and they form the internal “steps” of the DNA ladder. The specific sequence of these base pairs carries the genetic instructions used to build and operate an organism.
Let’s briefly clarify the other terms to avoid confusion:
- Amino acids are the building blocks of proteins, not DNA. DNA codes for amino acids but does not contain them structurally.
- Genes are segments of DNA that contain instructions for making proteins. They are composed of many nucleotide base pairs.
- Chromosomes are long strands of DNA coiled around proteins, containing many genes. They are much larger structures than the DNA ladder analogy describes.
Therefore, the correct and most precise answer is:
👉 Nucleotide base pairs form the rungs or steps of the DNA ladder.