Marker gene

Marker gene 

 A detectable genetic trait or segment of DNA that can be identified and tracked. genetic marker is a DNA sequence with a known physical location on a chromosome.

 marker gene is a gene used to determine if a nucleic acid sequence has been successfully inserted into an organism's DNA.

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 to it so that the two genes (the marker gene and the target gene) are genetically linked 

In particular, there are two sub-types of these marker genes: a selectable marker and a marker for screening.

Genetic markers can help link an inherited disease with the responsible gene. 

 Genetic markers are used to track the inheritance of a nearby gene that has not yet been identified, but whose approximate location is known.

Detection of the marker can be direct by RNA sequencing, or indirect using allozymes. Some of the methods used to study the genome or phylogenetics are RFLP, AFLP, RAPD, SSR. They can be used to create genetic maps of whatever organism is being studied.

The average size of a protein molecule allows one to predict that there are approximately 1,000 nucleotide pairs of coding sequence per gene. Since humans are thought to have about 100,000 genes, a total of about 100 million nucleotide pairs of coding DNA must be present in the human genome.

Gene transformation now are used to cure many diseases which have no curse  from drugs .