The question
How can four chemical letters describe every protein in your body?
The short answer
DNA uses four bases, read three at a time. That gives 64 possible “words”, which map onto 20 standard amino acids plus stop signals, with plenty of redundancy.
What science knows
Established ScienceDNA is written in four bases: adenine (A), cytosine (C), guanine (G) and thymine (T). When a gene is copied into RNA, uracil (U) replaces thymine.
In 1961 Francis Crick, Sydney Brenner and colleagues showed the code is read in triplets, and Marshall Nirenberg and Heinrich Matthaei found the first word: UUU means phenylalanine.
The pattern
Established ScienceSome of the numbers:
| Quantity | Value |
|---|---|
| Bases | 4 |
| Possible codons (4³) | 64 |
| Codons for amino acids | 61 |
| Stop codons | 3 (UAA, UAG, UGA) |
| Standard amino acids | 20 |
| Base pairs per helix turn | About 10.5 |
| Human genome | About 3.1 billion base pairs |
What is still uncertain
Active ResearchWhy life uses this particular code is still debated. Francis Crick suggested it might be a “frozen accident”; other researchers argue it was shaped to limit the damage of copying errors.
Why humans find it interesting
Historical FactJames Watson and Francis Crick published the double helix in 1953, relying on X-ray images made by Rosalind Franklin and Raymond Gosling.
Why CUE finds this interesting
CUE PerspectiveDNA is the most literal example of numbers carrying meaning: a small alphabet, read in fixed-size groups, produces the variety of life.
CUE works with a very different kind of code, the numbers of a birth date. These scientific relationships do not prove the CUE system, and CUE does not claim they do. But DNA is a reminder that simple symbols, combined by rules, can hold enormous information.