Related topics: genes · dna sequences · genetic variation

Origin story: Rewriting human history through DNA

For most of our evolutionary history—for most of the time anatomically modern humans have been on Earth—we've shared the planet with other species of humans. It's only been in the last 30,000 years, the mere blink of ...

A genetic tug-of-war between the sexes begets variation

In species with sexual reproduction, no two individuals are alike, and scientists have long struggled to understand why there is so much genetic variation. In a new study published in Nature Ecology & Evolution, a team of ...

First genome of spotted lanternfly built from a single insect

Agricultural Research Service (ARS) scientists, in cooperation with Pacific Biosciences and Penn State University, have published the first genome of the invasive Spotted Lanternfly (SLF) in the journal Gigascience and they ...

Improved mapping of Swedish genes from 1,000 individuals

People—or more specifically just Swedes—are more like chimpanzees than previously known. This is indicated in a genetic mapping of one thousand Swedish individuals, where new DNA sequences that should be included in the ...

Molecular biologists reveal new insights into tumor progression

University of Delaware molecular biologist Mona Batish and collaborators at Harvard Medical School and University of California, Los Angeles, have identified a new circular ribonucleic acid (RNA) that increases tumor activity ...

New insights into genetic basis of bird migration

A gene newly associated with the migratory patterns of golden-winged and blue-winged warblers could lend insight into the longstanding question of how birds migrate across such long distances.

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DNA sequence

A DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information as described by the central dogma of molecular biology.

The possible letters are A, C, G, and T, representing the four nucleotide bases of a DNA strand — adenine, cytosine, guanine, thymine — covalently linked to a phosphodiester backbone. In the typical case, the sequences are printed abutting one another without gaps, as in the sequence AAAGTCTGAC, read left to right in the 5' to 3' direction. Short sequences of nucleotides are referred to as oligonucleotides and are used in a range of laboratory applications in molecular biology. With regard to biological function, a DNA sequence may be considered sense or antisense, and either coding or noncoding. DNA sequences can also contain "junk DNA."

Sequences can be derived from the biological raw material through a process called DNA sequencing.

In some special cases, letters besides A, T, C, and G are present in a sequence. These letters represent ambiguity. Of all the molecules sampled, there is more than one kind of nucleotide at that position. The rules of the International Union of Pure and Applied Chemistry (IUPAC) are as follows:

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