Related topics: genes · dna sequences · genetic variation

A chimp-pig hybrid origin for humans?

(Phys.org) —These days, getting a Ph.D. is probably the last thing you want to do if you are out to revolutionize the world. If, however, what you propose is an idea, rather than a technology, it can still be a valuable ...

Genome sequencing project reveals new secrets about cat evolution

Researchers at the Texas A&M School of Veterinary Medicine & Biomedical Sciences (VMBS) and an interdisciplinary team of collaborators have uncovered new information about the history of cat evolution explaining how cats—including ...

The Y chromosome is disappearing: What will happen to men?

The Y chromosome may be a symbol of masculinity, but it is becoming increasingly clear that it is anything but strong and enduring. Although it carries the "master switch" gene, SRY, that determines whether an embryo will ...

Researchers suspend, image single DNA molecules

(PhysOrg.com) -- Studying chemical modifications in the chromosomes of cells is akin to searching for changes in coiled spaghetti. Scientists at Cornell have figured out how to stretch out tangled strands of DNA from chromosomes, ...

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 ...

Enzyme corrects more than one million faults in DNA replication

Scientists from the Medical Research Council (MRC) Institute of Genetics and Molecular Medicine (IGMM) at the University of Edinburgh have discovered an enzyme that corrects the most common mistake in mammalian DNA.

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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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