Sequence African genomes for Africa and the world: scientist

A $4.5 billion initiative to sequence the genomes of three million Africans would not only benefit a continent long neglected in gene-based healthcare, but advance understanding of genetic disease worldwide, the project leader ...


Biomarkers in fathers' sperm linked to offspring autism

Biomarkers in human sperm have been identified that can indicate a propensity to father children with autism spectrum disorder. These biomarkers are epigenetic, meaning they involve changes to molecular factors that regulate ...


DNA discovery could advance degenerative disease treatments

New research on the structure and dynamics of a branched form of DNA called a three-way junction could lead to more effectively targeted treatments for degenerative disorders like Huntington's Disease, scientists say.

Oncology & Cancer

A more sensitive way to detect circulating tumor cells

Breast cancer is the most frequently diagnosed cancer in women, and metastasis from the breast to other areas of the body is the leading cause of death in these patients. Detecting circulating tumor cells (CTCs) in the bloodstream ...

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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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