Glossary - Genetic (M)

Macrorestriction map

Map depicting the order of and distance between sites at which restriction enzymes cleave chromosomes.

Mapping

See: gene mapping, linkage map, physical map

Mapping population

The group of related organisms used in constructing a genetic map.

Marker

See: genetic marker

Mass spectrometry

An instrument used to identify chemicals in a substance by their mass and charge.

Megabase (Mb)

Unit of length for DNA fragments equal to 1 million nucleotides and roughly equal to 1 cM.
See also: centimorgan

Meiosis

The process of two consecutive cell divisions in the diploid progenitors of sex cells. Meiosis results in four rather than two daughter cells, each with a haploid set of chromosomes.
See also: mitosis

Mendelian inheritance

One method in which genetic traits are passed from parents to offspring. Named for Gregor Mendel, who first studied and recognized the existence of genes and this method of inheritance.
See also: autosomal dominant, recessive gene, sex-linked

Messenger RNA (mRNA)

RNA that serves as a template for protein synthesis.
See also: genetic code

Metaphase

A stage in mitosis or meiosis during which the chromosomes are aligned along the equatorial plane of the cell.

Microarray

Sets of miniaturized chemical reaction areas that may also be used to test DNA fragments, antibodies, or proteins.

Microbial genetics

The study of genes and gene function in bacteria, archaea, and other microorganisms. Often used in research in the fields of bioremediation, alternative energy, and disease prevention.
See also: model organisms, biotechnology, bioremediation

Microinjection

A technique for introducing a solution of DNA into a cell using a fine microcapillary pipet.

Micronuclei

Chromosome fragments that are not incorporated into the nucleus at cell division.

Mitochondrial DNA

The genetic material found in mitochondria, the organelles that generate energy for the cell. Not inherited in the same fashion as nucleic DNA.
See also: cell, DNA, genome, nucleus

Mitosis

The process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell.
See also: meiosis

Model organisms

A laboratory animal or other organism useful for research.

Modeling

The use of statistical analysis, computer analysis, or model organisms to predict outcomes of research.

Molecular biology

The study of the structure, function, and makeup of biologically important molecules.

Molecular farming

The development of transgenic animals to produce human proteins for medical use.

Molecular genetics

The study of macromolecules important in biological inheritance.

Molecular medicine

The treatment of injury or disease at the molecular level. Examples include the use of DNA-based diagnostic tests or medicine derived from DNA sequence information.

Monogenic disorder

A disorder caused by mutation of a single gene.
See also: mutation, polygenic disorder

Monogenic inheritance

See: monogenic disorder

Monosomy

Possessing only one copy of a particular chromosome instead of the normal two copies.
See also: cell, chromosome, gene expression, trisomy

Morbid map

A diagram showing the chromosomal location of genes associated with disease.

Mouse model

See: model organisms

Multifactorial or multigenic disorder

See: polygenic disorder

Multiplexing

A laboratory approach that performs multiple sets of reactions in parallel (simultaneously); greatly increasing speed and throughput.

Murine

Organism in the genus Mus. A rat or mouse.

Mutagen

An agent that causes a permanent genetic change in a cell. Does not include changes occurring during normal genetic recombination.

Mutagenicity

The capacity of a chemical or physical agent to cause permanent genetic alterations.
See also: somatic cell genetic mutation

Mutation

Any heritable change in DNA sequence.
See also: polymorphism