Genetic marker

As a marker ( German " mark", also called marker or molecular markers ) is called in molecular biology clearly identifiable, short stretches of DNA whose location is known in the genome.

Such marker genes are available in the genome (see below types of n markers). But you can also incorporate marker genes by genetic engineering. These reporter genes are chosen such that one can easily recognize their presence in an organism. For example, genes for fluorescent proteins or reporter enzymes together with others, not so easily recognizable genes, a microorganism can be added. Those of his descendants, who have inherited the gene sequence can be seen then, for example because they fluoresce. For them, that is, the probability is very high that they have inherited the genes that sit next to the marker gene in the added gene sequence.

Uses of natural markers

• AFLP: Amplified Fragment Length Polymorphisms
• RAPD: Randomly Amplified Polymorphic DNA
• RFLP: restriction fragment length polymorphisms (Restriction Fragment Length Polymorphisms ) affect cleavage sites for restriction enzymes.
• SNP: Single nucleotide polymorphisms - point mutations. Certain SNPs are correlated with disease and can therefore serve as molecular markers for a particular disease.
• STR: short tandem repeats are short repeating segments of up to 200 nucleotides that are repeated up to 20 times. The human genome has approximately 650,000 to such microsatellites. Certain microsatellites occur with certain diseases.
• VNTR: variable number tandem repeats in the genome, there are several places where we find VNTRs. These loci are named according to genes, in addition to which they occur. In contrast to microsatellite ( STR ) they are long repetitive sections.