marker Medspeak A value or indicator of the presence of a disease. Genetic marker Any segment of DNA that can be identified, or whose chromosomal location is known, so that it can be used as a reference point to map or locate other genes. These differences, collectively called as polymorphisms can be mapped and identified. Also called: biomarker 2. Molecular biology An identifiable physical location on a chromosome (e.g., restriction enzyme cutting site, gene, minisatellite, microsatellite), the inheritance of which can be monitored. A marker gene can serve as a flag for another gene, sometimes called the target gene. marker meaning: 1. a sign that shows where something is: 2. a characteristic feature, gene, or substance that…. biological marker n 1. Narration. Marker gene: A detectable genetic trait or segment of DNA that can be identified and tracked. […] This usually deals with running an experiment (assay) to determine the presence, absence, and with some markers, abundance of a specific protein. home >> biology >> dictionary A marker pen, marking pen, felt-tip pen, or marker , is a pen which has its own ink-source, and usually a tip made of a porous material, such as felt or nylon. flanking marker An identifiable region (i.e., polymorphism ) located near a gene which can be used in linkage studies to track the coinheritance of the gene in question. A genetic marker is a landmark. (Medicine) a substance, physiological characteristic, gene, etc that indicates, or may indicate, the presence of disease, a physiological abnormality or a psychological condition. Learn more. NCI's Dictionary of Cancer Terms provides easy-to-understand definitions for words and phrases related to cancer and medicine. This is unlike an intragenic marker which is located within the gene itself. For example, you can use a protein marker to mark an extracellular protein such as a Lipopolysaccharide (LPS) on bacteria. Genetic marker s: Alleles of genes, or DNA polymorphisms , used as experimental probe s to keep track of an individual, a tissue , a cell , a nucleus , a chromosome, or a gene. Full article >>> ADVERTISEMENTS: Molecular Markers: A molecular marker is a DNA sequence in the genome which can be located and identified. Genetic markers are used to track the inheritance of a nearby gene that has not yet been identified, but whose approximate location is known. A protein marker is just that - a marker for specific proteins. Biology Glossary search by EverythingBio.com A gene whose expression allows one to identify cells that have been transforrned or transfected with a vector containing the marker gene. Genetic marker, any alteration in a sequence of nucleic acids or other genetic trait that can be readily detected and used to identify individuals, populations, or species or to identify genes involved in inherited disease. The genetic marker itself may be a part of a gene or may have no known function. 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 and are usually inherited together. As a result of genetic alterations (mutations, insertions, deletions), the base composition at a particular location of the genome may be different in different plants.