DNA

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The initial proposal of DNA structure

Diagram of a DNA double helix segment showing two strands with labeled components: adenine (A), thymine (T), cytosine (C), guanine (G), phosphate groups (P), and deoxyribose sugars (S). The bases pair across the strands, and the 3' and 5' ends are indicated at each strand's termini.

How DNA influences inherited traits

Blue digital illustration of a DNA double helix structure with additional blurred DNA strands in the background.

Diagram of a DNA polynucleotide chain showing linked deoxyribose sugars, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, thymine), with an inset comparing ribose and uracil in RNA.

Astronaut holding a rainbow lollipop against a starfield, with arrows toward text reading: Sugar in Space?

Genetically modified humans

Finding prehistoric family ties with modern DNA

model of a DNA molecule

The human genome

DNA: Media

chemical compound

Videos

How DNA influences inherited traits

How DNA influences inherited traits

This video introduces the basics of DNA, the chemical that underlies life on Earth.

Video: Encyclopædia Britannica, Inc.

Astronaut holding a rainbow lollipop against a starfield, with arrows toward text reading: Sugar in Space?

How Did We Find Sugar in Space?

It's the same sugar found in strawberries and raspberries on Earth.

Video: Encyclopædia Britannica, Inc.

Genetically modified humans

Genetically modified humans

CRISPR and genetically modified humans.

Video: © American Chemical Society (A Britannica Publishing Partner)

Finding prehistoric family ties with modern DNA

Finding prehistoric family ties with modern DNA

View researchers at the anthropological institute in Göttingen studying DNA taken...

Video: Contunico © ZDF Studios GmbH, Mainz; Thumbnail © Vladislav Kochelaevskiy/Dreamstime.com; © Photoblueice/Dreamstime.com

Uncover the genome similarities and differencess between chimpanzees and human beings

Uncover the genome similarities and differencess between chimpanzees and human beings

Comparing the similarities and differences between the genomes of chimpanzees (Pan...

Video: © MinuteEarth (A Britannica Publishing Partner)

Learn about CRISPR technology and how it can transform medicine and society

Learn about CRISPR technology and how it can transform medicine and society

What is CRISPR, and how does it stand to transform medicine and society?

Video: © World Science Festival (A Britannica Publishing Partner)

Fascinating facts about crystals

Fascinating facts about crystals

Discover five facts about crystals.

Video: © American Chemical Society (A Britannica Publishing Partner)

Explore Paul Rothemund's DNA origami and its future application in medical diagnostics, drug delivery, tissue engineering, energy, and the environment

Explore Paul Rothemund's DNA origami and its future application in medical diagnostics, drug delivery, tissue engineering, energy, and the environment

DNA origami, developed by American computer scientist and bioengineer Paul Rothemund,...

Video: Science in Seconds (www.scienceinseconds.com) (A Britannica Publishing Partner)

Eukaryotic vs. Prokaryotic Cells: Key Differences Explained

Eukaryotic vs. Prokaryotic Cells: Key Differences Explained

Learn about the difference between prokaryotes and eukaryotes.

Video: Encyclopædia Britannica, Inc.

How gene therapy can treat diseases

How gene therapy can treat diseases

Gene therapy seeks to repair genetic mutations through the introduction of healthy,...

Video: Encyclopædia Britannica, Inc.

What are chromosomes?

What are chromosomes?

Each species has a unique set of chromosomes which are the carriers of genetic information.

Video: Encyclopædia Britannica, Inc.

Learn how the DNA molecules divide during the process of cell division called mitosis

Learn how the DNA molecules divide during the process of cell division called mitosis

The cell cycle is an ordered sequence of events that prepares a cell for the process...

Video: Encyclopædia Britannica, Inc.

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...

Video: Encyclopædia Britannica, Inc.

Images

The initial proposal of DNA structure

The initial proposal of DNA structure

The structure of DNA proposed by James Watson and Francis Crick, which was accompanied...

Encyclopædia Britannica, Inc.

Diagram of a DNA double helix segment showing two strands with labeled components: adenine (A), thymine (T), cytosine (C), guanine (G), phosphate groups (P), and deoxyribose sugars (S). The bases pair across the strands, and the 3' and 5' ends are indicated at each strand's termini.

The arrangement of nucleotide bases within DNA

DNA structure, showing the nucleotide bases cytosine (C), thymine (T), adenine (A),...

Encyclopædia Britannica, Inc.

Blue digital illustration of a DNA double helix structure with additional blurred DNA strands in the background.

DNA strands

Illustration of DNA strands

© Shutter2U/stock.adobe.com

Diagram of a DNA polynucleotide chain showing linked deoxyribose sugars, phosphate groups, and nitrogenous bases (adenine, guanine, cytosine, thymine), with an inset comparing ribose and uracil in RNA.

The polynucleotide chain of deoxyribonucleic acid (DNA)

A portion of the polynucleotide chain of deoxyribonucleic acid (DNA), with an inset...

Encyclopædia Britannica, Inc.

model of a DNA molecule

model of a DNA molecule

Model of a DNA molecule.

© Photodisc/Getty Images

The human genome

The human genome

Bands of DNA representing a segment of the human genome.

Courtesy of the National Library of Medicine

DNA extraction and recombinant DNA technology

DNA extraction and recombinant DNA technology

The process of DNA extraction is necessary to isolate molecules of DNA from cells...

Dr. Dominik Refardt/University of Basel, Switzerland.

Computer monitor displaying DNA sequencing data with multicolored horizontal bands and vertical columns, labeled with numerical markers along the left side.

DNA sequencing

A nucleotide sequence determined using DNA sequencing technologies.

© Ryan McVay—Photodisc/Getty Images

Diagram of a DNA double helix showing its twisted ladder structure, with a close-up of the sugar-phosphate backbone, paired nitrogenous bases (adenine, thymine, cytosine, guanine), and labeled nucleotides and hydrogen bonds.

DNA; human genome

The human genome is made up of approximately three billion base pairs of deoxyribonucleic...

Encyclopædia Britannica, Inc.

Illustration of two blue double helix DNA strands with colored base pairs, representing deoxyribonucleic acid structure.

DNA

An illustration of strands of DNA.

© Benjaminet/stock.adobe.com

Diagram showing the step-by-step process of DNA packaging: DNA wraps around histone proteins to form nucleosomes, which condense into chromatin fibers that further coil and fold to create a compact chromosome structure.

DNA wraps around proteins called histones to form units known as nucleosomes. These...

Encyclopædia Britannica, Inc.

Diagram of DNA replication in higher organisms showing a double helix unwinding at multiple origins, with enzymes such as helicase, polymerase, ligase, and topoisomerase labeled, along with replication forks, Okazaki fragments, and direction of strand synthesis.

DNA replication in higher organisms begins at multiple origins of replication and...

Encyclopædia Britannica, Inc.

Diagram showing DNA winding around blue histone octamers to form nucleosomes, which coil together into a solenoid chromatin fiber. An inset highlights DNA wrapped around a single histone octamer.

Histones and nucleosomes

DNA wrapped around clusters of histone proteins to form nucleosomes, which can coil...

Encyclopædia Britannica, Inc.

Diagram illustrating the process of protein synthesis: DNA unzips in the nucleus, messenger RNA (mRNA) forms on the DNA strands, and then mRNA moves to a ribosome where transfer RNA (tRNA) helps assemble amino acids into a protein chain.

DNA and protein synthesis

DNA in the cell nucleus carries a genetic code, which consists of sequences of adenine...

Encyclopædia Britannica, Inc.

Diagram illustrating semiconservative DNA replication, showing a double helix unwinding into two template strands. New nucleotides are added by DNA polymerase to form leading and lagging strands, with Okazaki fragments joined by DNA ligase. Helicase, single-strand binding proteins, and the replication fork are labeled.

semiconservative DNA replication

In semiconservative DNA replication an existing DNA molecule is separated into two...

Encyclopædia Britannica, Inc.

Diagram showing the basic structure and expression of a gene, with DNA made of exons and introns, transcription to RNA, splicing to form mRNA, translation into an amino acid chain, and posttranslational modification to form a protein.

gene; intron and exon

Genes are made up of promoter regions and alternating regions of introns (noncoding...

Encyclopædia Britannica, Inc.

Failure of DNA repair mechanismsDNA repair mechanisms maintain the integrity of DNA, which often acquires mutations during replication. If these mechanisms fail, or if the cell does not undergo apoptosis (a genetically encoded cell “suicide”), more mutations may occur, and the cells will proliferate. If the proliferation is slow and localized to the area in which it begins, the result is a benign tumour. With fast, uncontrolled growth and the invasion of other tissues, a malignant tumour arises.

Failure of DNA repair mechanismsDNA...

Encyclopædia Britannica, Inc.

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