DNA vs. Chromosome: What's the Difference?
They're deeply related — a chromosome is essentially DNA, just packaged. DNA is the molecule itself: the famous double helix that stores genetic instructions as a sequence of chemical 'letters'. A chromosome is a single, very long DNA molecule wound tightly around proteins so it fits inside a cell. So DNA is the material; a chromosome is how that material is bundled up. Humans have 46 chromosomes, each one a tightly-coiled DNA molecule.
See the difference, explained visually.
Watch a 2-minute animated lesson comparing dna and chromosome.
At a glance
| DNA | Chromosome | |
|---|---|---|
| What it is | The genetic molecule (double helix) | DNA packaged with proteins |
| Form | A long thread of code | A coiled, compact bundle |
| Scale | The raw material | The organized structure |
| Contains | The sequence of genetic 'letters' | One long DNA molecule + proteins |
| In humans | ~3 billion base pairs | 46 chromosomes |
Which should you use?
DNA
Talk about DNA when you mean the molecule and its code — the sequence of bases carrying instructions.
Chromosome
Talk about a chromosome when you mean the packaged structure — the coiled-up bundle that organizes DNA inside the cell.
Frequently asked questions
- Is a chromosome made of DNA?
- Yes. A chromosome is a single long DNA molecule wound around proteins (called histones) so it packs neatly into the cell.
- What's the difference between DNA, a gene, and a chromosome?
- DNA is the molecule; a gene is a short segment of DNA that codes for something; a chromosome is a whole DNA molecule packaged up, containing many genes.
- Why is DNA packaged into chromosomes?
- A cell's DNA is about two metres long if stretched out. Coiling it into chromosomes lets it fit inside the tiny nucleus and be copied and divided neatly.