# DNA

Source: https://onco.cc/terms/dna-term/  
OnCo record `dna-term` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The long molecule that stores the instructions for building and running a cell, written in a four-letter chemical alphabet. Cancer is fundamentally a disease of damaged DNA.

## Summary

DNA is a twisted ladder of two strands whose rungs are pairs of four bases (A, T, C, G); the order of those bases encodes about 20,000 genes plus the switches that control them. Every time a cell divides it must copy all three billion letters, and copying errors, radiation, tobacco chemicals and other insults introduce mutations that accumulate over a lifetime. Sequencing a tumour's DNA reveals which genes are broken and often which drug might work; sequencing DNA fragments in blood (ctDNA) lets doctors track the tumour without a biopsy.

## Fields

- Kind: Term
- Last checked: 2026-09-09
- Also known as: deoxyribonucleic acid; double helix; genetic code; genome

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/DNA
- Wikipedia: https://en.wikipedia.org/wiki/DNA

## Connected records

- terms: [Chromosome](https://onco.cc/terms/chromosome/), [Circulating tumour DNA (ctDNA)](https://onco.cc/terms/ctdna/), [Gene](https://onco.cc/terms/gene/), [Genomic profiling](https://onco.cc/terms/genomic-profiling/), [Mutation](https://onco.cc/terms/mutation/), [Next-generation sequencing (NGS)](https://onco.cc/terms/ngs/), [Nucleus](https://onco.cc/terms/nucleus/), [Radiotherapy](https://onco.cc/terms/radiotherapy/), [RNA](https://onco.cc/terms/rna/)

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JSON: https://onco.cc/api/v1/entities/dna-term.json