Level of life
Gene
A basic unit of heredity: a stretch of DNA with instructions for a product such as a protein or a functional RNA.
DNA
The molecule that stores the genetic instructions of all cellular life: two strands wound into a double helix and held together by base pairs.Source: NHGRISource: MedlinePlusSource: Watson & Crick, 1953
Step 1 of 7ReadingLevel of life
How DNA connects
DNA contains
DNA includes
Process
Base pairing
In DNA, A pairs with T and G pairs with C (RNA uses U instead of T). The matching lets each strand act as a template for the other.
Molecule
Transposable elements
Stretches of DNA that can move to new places in the genome, first described by Barbara McClintock in maize.
DNA is used by
Process
DNA replication
Copying DNA before a cell divides. Each new double helix keeps one original strand and gains one new strand.
Technology or method
Recombinant DNA
DNA joined from different sources, the starting point of genetic engineering and of medicines such as recombinant insulin.
Technology or method
DNA sequencing
Reading the order of the bases in DNA, from single genes to whole genomes.
Technology or method
Gene editing
Making targeted changes to DNA in living cells. Newer base and prime editors change letters without cutting both strands.
Emerging researchOpen in Biotech Lab
DNA is found in
Structure
Chromosome
A single DNA molecule packaged with proteins. Human cells usually carry 23 pairs, 46 chromosomes in all.
DNA is related to
Process
Mutation
A change in a DNA sequence. Mutations arise from copying errors or damage, and their effects range from none at all to disease.
Explore further
Your progress
Sources & further reading
The explanations on this page are our own summaries of these sources. Follow a link to read the original; if anything here disagrees with it, the original wins. How we choose and check sources.
Deoxyribonucleic Acid (DNA) Fact Sheet (opens the original in a new tab)
National Human Genome Research Institute. genome.gov. National Human Genome Research Institute, NIH.
Fact sheetGovernment sourceWhat is DNA? (opens the original in a new tab)
MedlinePlus Genetics. MedlinePlus Genetics. U.S. National Library of Medicine, NIH.
ReferenceGovernment sourceEducationalMolecular structure of nucleic acids; a structure for deoxyribose nucleic acid (opens the original in a new tab)
Watson JD, Crick FH (1953). Nature 171(4356):737-738.
Proposed the double-helix model of DNA.
Historical paperPrimary research