Nucleic acid

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Images & Videos

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.

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's double helix structure was discovered

The initial proposal of DNA structure

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.

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.

RNA polymerase II; messenger RNA

Diagram showing the process of crossing over during meiosis, where homologous chromosomes exchange genetic material, followed by two cell divisions that result in four genetically unique haploid daughter cells.

Large biological molecules: Carbs, lipids, proteins, and nucleic acids

Study how bacteriophages replicate by injecting nucleic acid into a bacteria cell to create virions

At a Glance

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nucleic acid summary

Nucleic acid: Media

chemical compound

Videos

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.

Large biological molecules: Carbs, lipids, proteins, and nucleic acids

Large biological molecules: Carbs, lipids, proteins, and nucleic acids

Overview of large biological molecules.

Video: Encyclopædia Britannica, Inc.

Study how bacteriophages replicate by injecting nucleic acid into a bacteria cell to create virions

Study how bacteriophages replicate by injecting nucleic acid into a bacteria cell to create virions

The cycle of infection results in the death of the host cell and the release of many...

Video: Encyclopædia Britannica, Inc.

Images

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.

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.

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 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 are coiled...

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.

RNA polymerase II; messenger RNA

RNA polymerase II; messenger RNA

Illustration of an RNA polymerase II molecule, an enzyme in mammalian cells that...

David Bushnell, Ken Westover, Roger Kornberg—Stanford University/National Institute of General Medical Sciences/National Institutes of Health

Diagram showing the process of crossing over during meiosis, where homologous chromosomes exchange genetic material, followed by two cell divisions that result in four genetically unique haploid daughter cells.

meiosis

During meiosis, an event known as chromosomal crossing over sometimes occurs as a...

Encyclopædia Britannica, Inc.

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