Glossary
Genetics glossary
914 definitions · page 13 of 16.
- Met
- Methionine (an amino acid).
- metabolism
- The chemical reactions that occur in a living cell.
- metacentric chromosome
- A chromosome having its centromere in the middle. See also acrocentric chromosome
- metafemale
- A fruit fly with an X chromosome:Autosome ratio greater than unity.
- metagon
- An RNA necessary for the maintenance of mu particles in Paramecium.
- metamale
- A fruit fly with X chromosome:Autosome ratio below 0.5.
- metamere
- Segmental repeat unit in higher animals.
- metaphase
- The stage of mitosis or meiosis in which spindle fibers are attached to kinetochores and the chromosomes are positioned in the equatorial plane of the cell. An intermediate stage of nuclear division when chromosomes align along the equatorial plane of the…
- metaphase plate
- The plane of the equator of the spindle into which chromosomes are positioned during metaphase.
- metastasis
- The migration of cancerous cells to other parts of the body.
- methylation
- Modification of a molecule by the addition of a methyl group.
- microtubules
- Hollow cylinders made of the protein tubulin that form, among other things, the spindle fibers.
- midparent value
- The mean of the values of a quantitative phenotype for two specific parents.
- migration
- Movement of individuals between otherwise reproductively isolated populations.
- mimicry
- A phenomenon in which an individual; gains an advantage by looking like the individuals of a different species.
- minimal medium
- A culture medium for microorganisms that contains the minimal necessities for growth of the wild-type. A medium containing only inorganic salts, a carbon source, and water.
- mismatch repair
- A form of excision repair initiated at the sites of mismatched bases in DNA.
- missense mutation
- mutations that at change a codon for one amino acid into a codon for a different amino acid.
- mitochondrial cytopathy
- Human disorder caused by point mutation or deletion in mitochondrial DNA; inherited maternally.
- mitochondrion
- A eukaryotic organelle that is the site of ATP synthesis and of the citric acid cycle. The eukaryotic cellular organelle in which the Krebs cycle and electron transport reactions take place.
- mitosis
- The nuclear division producing two daughter nuclei identical to the original nucleus. A type of nuclear division that produces two daughter nuclei identical to the parent nucleus normally just prior to cell division. See endomitosis, cytokinesis.
- mitotic crossover
- A crossover resulting from the pairing of homologous chromosomes in a diploid during mitosis.
- mixed codon family
- Group of four codons sharing their first two bases but coding for more than one amino acid.
- mode
- The single class in a statistical distribution having the greatest frequency.
- modifier gene
- A gene that affects the phenotypic expression of another gene.
- molecular chaperone
- A protein that aids in the folding of a second protein. The chaperone prevents proteins from taking conformations that would be inactive.
- molecular evolutionary clock
- A measurement of evolutionary time in nucleotide substitutions per year.
- molecular genetics
- The study of the molecular processes underlying gene structure and function.
- molecular imprinting
- The phenomenon in which there is differential expression of a gene depending on whether it was maternally or paternally inherited. Paternal imprinting means that an allele inherited from the father is not expressed in offspring. Maternal imprinting means…
- monocistronic mRNA
- An mRNA that codes for only one protein.
- monoclonal antibody
- The unique immunoglobulin molecule (antibody) produced by a clone of cells derived from a fusion of a B lymphocyte with a myeloma cell.
- monoecious plant
- A plant species in which male and female organs are found on the same plant but in different flowers (for example maize).
- monohybrid
- Offspring of parents that differ in only one genetic characteristic. Usually implies heterozygosity at a single locus under study.
- monohybrid cross
- A cross between two individuals identically heterozygous at one gene pair for example, Aa x Aa.
- monoploid
- A cell having only one chromosome set (usually as an aberration) or an organism composed of such cells.
- monosomic
- A diploid cell missing a single chromosome. A cell or individual that is basically diploid but that has only one copy of one particular chromosome type and thus has chromosome number 2n - 1.
- morphological species concept
- Organisms are classified in the same species if they appear identical by morphological (anatomical) criteria.
- mosaic
- A chimera; a tissue containing two or more genetically distinct cell types, or an individual composed of such tissues. Individual made up of two or more genetically distinct cell lines.
- mosaicism
- The condition of being a mosaic. See mosaic.
- mtDNA
- Mitochondrial DNA.
- mu particle
- Bacteria-like particle found in the cytoplasm of Paramecium that have the mate-killer phenotype.
- mu phage
- A kind (species) of phage with properties similar to those of insertion sequences, being able to insert, transpose, and cause chromosome rearrangements and mutations.
- Mullerian mimicry
- A form of mimicry in which noxious species evolve to resemble each other.
- multihybrid
- An organism heterozygous at numerous loci.
- multimeric structure
- A structure composed of several identical or different subunits held together by weak bonds.
- multinomial expansion
- The terms generated when a multinomial is raised to a power.
- multiple allelism
- The existence of several known alleles of a gene.
- multiple-factor hypothesis
- A hypothesis to explain quantitative variation by assuming the interaction of a large number of genes (polygenes) each with a small additive effect on the character.
- multiple-hit hypothesis
- The proposal that a single cell must receive a series of mutational events in order to become malignant or cancerous.
- multiplicity of infection (moi)
- The average number of phage particles that infect a single bacterial cell in a specific experiment.
- mutability
- The ability to change.
- mutagen
- An agent that is capable of increasing the mutation rate .
- mutant
- An organism or cell carrying a mutation. An alternative phenotype to the wild-type; the phenotype produced by a non-wildtype allele.
- mutant allele
- An allele differing from the allele found in the standard or wild type organism.
- mutant screening
- The process of screening for mutations showing abnormalities in a certain structure or in a particular function, as a preparation for genetic analysis of that strucutre or function.
- mutant site
- The damaged or altered area within a mutated gene.
- mutation
- (1) The process producing a gene or a chromosome differing from the wild-type. (2) The gene or chromosome that results from such a process.
- mutation breeding
- Use of mutagens to develop variants that can increase agricultural yield.
- mutation event
- The actual occurrence of a mutation in time and space.
- mutation frequency
- The frequency of mutations in a population.