Marker gene

Marker gene

A marker gene is a gene used in molecular biology to determine if a nucleic acid sequence has been successfully inserted into an organism's DNA. There are two types of marker genes: a selectable marker and a marker for screening.

Selectable marker

A selectable marker protects the organism from a selective agent that would normally kill it or prevent its growth. In most applications, only one in a several billion cells will take up DNA. Rather than checking every single cell, scientists use a selective agent to kill all cells that do not contain the foreign DNA, leaving only the desired ones.

Antibiotics are the most common selective agents. In bacteria, antibiotics are used almost exclusively. In plants, antibiotics that kill the chloroplast are often used as well, although tolerance to salts and growth-inhibiting hormones is becoming more popular. In mammals, resistance to antibiotics that would kill the mitochondria is used as a selectable marker.

Marker for screening

A marker for screening will make cells containing the gene look different. There are three types of screening commonly used:

  • Green fluorescent protein makes cells glow green under UV light. A specialized microscope is required to see individual cells. Yellow and red versions are also available, so scientists can look at multiple genes at once. It is commonly used to measure gene expression.
  • GUS assay (using β-glucuronidase) is an excellent method for detecting a single cell by staining it blue without using any complicated equipment. The drawback is that the cells are killed in the process. It is particularly common in plant science.
  • Blue/white screening is used in both bacteria and eukaryotic cells. The bacterial lacZ gene encodes a beta-galactosidase enzyme. When media containing certain galactosides (e.g. X-gal) is added, cells expressing the gene convert the X-gal to a blue product and can be seen with the naked eye.

See also

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Look at other dictionaries:

  • marker gene — marker gene. См. маркерный ген. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • Marker gene — A detectable genetic trait or segment of DNA that can be identified and tracked. A marker gene can serve as a flag for another gene, sometimes called the target gene. A marker gene must be on the same chromosome as the target gene and near enough …   Medical dictionary

  • marker gene — Genetic marker; gene of known position and conspicuous in its action …   Dictionary of invertebrate zoology

  • marker gene — Gene that confers some readily detectable phenotype on cells carrying the gene, either in culture, or in transgenic or chimeric organisms. Gene could be an enzymic reporter gene, a selectable marker conferring antibiotic resistance, or a cell… …   Dictionary of molecular biology

  • marker gene — noun : a gene that serves as a genetic marker * * * Genetics. See genetic marker …   Useful english dictionary

  • marker gene — mark′er gene n. gen genetic marker …   From formal English to slang

  • marker gene — A gene of known function or known location, used for marker assisted selection or genetic studies …   Glossary of Biotechnology

  • marker gene — Genetics. See genetic marker. * * * …   Universalium

  • marker gene — noun A gene with a known location in a chromosome; used to track the insertion of DNA into organisms …   Wiktionary

  • Gene trapping — is a high throughput approach that is used to introduce insertional mutations across the mammalian genome. It is performed with gene trap vectors whose principal element is a gene trapping cassette consisting of a promoterless reporter gene… …   Wikipedia

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