double helix

References

Videos

How DNA's double helix structure was discovered

double helix

genetics

Written by

The Information Architects of Encyclopaedia Britannica

Last updated

June 25, 2026

Quick Summary

How DNA's double helix structure was discovered — How DNA's double helix structure was discovered The animated structure of a DNA molecule. Deoxyribose sugar molecules and phosphate molecules form the outer edges of the DNA double helix, and base pairs bind the two strands to one another.

The double helix is the fundamental structure of DNA, the molecule that carries genetic information. Discovered by James Watson and Francis Crick in 1953, based on the work of Rosalind Franklin and Maurice Wilkins, this structure resembles a twisted ladder. It consists of two intertwined strands of nucleotides, with the sides made of sugar and phosphate groups and the rungs formed by paired nitrogenous bases: adenine (A) always pairs with thymine (T), and guanine (G) always pairs with cytosine (C). This specific pairing and the double helix structure are crucial for DNA's ability to replicate and pass genetic information from one generation to the next.123

Summary created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

4 Britannica Sources

Ask Britannica AI about this topic

Britannica doesn't have a full article on this topic, so we've curated a list of our relevant coverage.

reproduction
Molecular replication
…in the shape of a double helix (spring). The rungs, which join the two sides of the ladder, are made up of two terminal bases. There are four bases in DNA: thymine, cytosine, adenine, and guanine. In the middle of each rung a base from one strand of DNA is…
Read More
…in the shape of a double helix (spring). The rungs, which join the two sides of the ladder, are made up of two terminal bases. There are four bases in DNA: thymine, cytosine, adenine, and guanine. In the middle of each rung a base from one strand of DNA is…
Read More

cell
DNA: the genetic material
…DNA molecule (called the DNA double helix). In this model, each strand serves as a template in the synthesis of a complementary strand. Subsequent research confirmed the Watson and Crick model of DNA replication and showed that DNA carries the genetic information for reproduction of the entire cell.
Read More
…DNA molecule (called the DNA double helix). In this model, each strand serves as a template in the synthesis of a complementary strand. Subsequent research confirmed the Watson and Crick model of DNA replication and showed that DNA carries the genetic information for reproduction of the entire cell.
Read More

scientific modeling
…models, such as the three-dimensional double-helix model of DNA, are used primarily to visualize an object or system, often being created from experimental data. Other models are intended to describe an abstract or hypothetical behaviour or phenomenon. For example, predictive models, such as those employed in weather forecasting or in…
Read More
…models, such as the three-dimensional double-helix model of DNA, are used primarily to visualize an object or system, often being created from experimental data. Other models are intended to describe an abstract or hypothetical behaviour or phenomenon. For example, predictive models, such as those employed in weather forecasting or in…
Read More

nucleic acid
Chemical structure
…around each other, forming a double helix. The two strands, though identical, run in opposite directions as determined by the orientation of the 5′ to 3′ phosphodiester bond. The sugar-phosphate chains run along the outside of the helix, and the bases lie on the inside, where they are linked to…
Read More
…around each other, forming a double helix. The two strands, though identical, run in opposite directions as determined by the orientation of the 5′ to 3′ phosphodiester bond. The sugar-phosphate chains run along the outside of the helix, and the bases lie on the inside, where they are linked to…
Read More