Sense (molecular biology)
From Wikipedia, the free encyclopedia
Sense, when applied in a molecular biology context, is a general concept used to compare the polarity of nucleic acid molecules, particularly RNA, to other nucleic acid molecules. Depending on the context within molecular biology, sense may have slightly different meanings.
Contents |
[edit] RNA sense
In virology, the genome of a RNA virus can be said to be either positive-sense, also known as a "plus-strand", or negative-sense, also known as a "minus-strand". In most cases, the terms sense and strand are used interchangeably, making such terms as positive-strand equivalent to positive-sense, and plus-strand equivalent to plus-sense. Whether a virus is positive-sense or negative-sense can used as a basis for classifiying viruses.
Positive-sense viral RNA signifies that a particular viral RNA sequence may be directly translated into the desired viral proteins. Therefore, in positive-sense RNA viruses, the viral RNA genome is identical to the viral mRNA, and can be immediately translated by the host cell. Negative-sense viral RNA is complementary to the viral mRNA and thus must be converted to positive-sense RNA by an RNA polymerase prior to translation.
[edit] DNA sense
Molecular biologists call a DNA strand sequence sense if it is translated or translatable, and they call its complement antisense. It follows then, somewhat paradoxically, that the template for transcription is the antisense strand. The resulting transcript is an RNA replica of the sense strand and is itself sense.
[edit] Ambisense
A genome which contains both positive-sense and negative-sense is said to be ambisense.
[edit] Antisense mRNA
Antisense mRNA is an mRNA transcript that is complementary to endogenous mRNA, in other words, the non-coding strand complementary to the coding sequence of mRNA. Introducing a transgene coding for antisense mRNA is a technique used to block expression of a gene of interest. Radioactively-labelled antisense mRNA can be used to show the level of transcription of genes in various cell types. Some alternative antisense structural types are being experimentally applied as antisense therapy, with at least one antisense therapy approved for use in humans.
[edit] See also
[edit] References
- Prescott, L. (1993). Microbiology, Wm. C. Brown Publishers, ISBN 0-697-01372-3
- Viral replication and genetics - Google's cache of a page from the International Veterinary Information Service
