- alternation of generations
- a life-cycle type in which the diploid and haploid stages alternate
- aneuploid
- an individual with an error in chromosome number; includes deletions and duplications of chromosome segments
- autosome
- any of the non-sex chromosomes
- chiasmata
- (singular = chiasma) the structure that forms at the crossover points after genetic material is exchanged
- chromosome inversion
- the detachment, 180° rotation, and reinsertion of a chromosome arm
- crossing over
- (also, recombination) the exchange of genetic material between homologous chromosomes resulting in chromosomes that incorporate genes from both parents of the organism forming reproductive cells
- diploid-dominant
- a life-cycle type in which the multicellular diploid stage is prevalent
- euploid
- an individual with the appropriate number of chromosomes for their species
- fertilization
- the union of two haploid cells typically from two individual organisms
- gametophyte
- a multicellular haploid life-cycle stage that produces gametes
- germ cell
- a specialized cell that produces gametes, such as eggs or sperm
- haploid-dominant
- a life-cycle type in which the multicellular haploid stage is prevalent
- interkinesis
- a period of rest that may occur between meiosis I and meiosis II; there is no replication of DNA during interkinesis
- karyogram
- the photographic image of a karyotype
- karyotype
- the number and appearance of an individuals chromosomes, including the size, banding patterns, and centromere position
- life cycle
- the sequence of events in the development of an organism and the production of cells that produce offspring
- meiosis
- a nuclear division process that results in four haploid cells
- meiosis I
- the first round of meiotic cell division; referred to as reduction division because the resulting cells are haploid
- meiosis II
- the second round of meiotic cell division following meiosis I; sister chromatids are separated from each other, and the result is four unique haploid cells
- monosomy
- an otherwise diploid genotype in which one chromosome is missing
- nondisjunction
- the failure of synapsed homologs to completely separate and migrate to separate poles during the first cell division of meiosis
- polyploid
- an individual with an incorrect number of chromosome sets
- recombinant
- describing something composed of genetic material from two sources, such as a chromosome with both maternal and paternal segments of DNA
- reduction division
- a nuclear division that produces daughter nuclei each having one-half as many chromosome sets as the parental nucleus; meiosis I is a reduction division
- somatic cell
- all the cells of a multicellular organism except the gamete-forming cells
- sporophyte
- a multicellular diploid life-cycle stage that produces spores
- synapsis
- the formation of a close association between homologous chromosomes during prophase I
- tetrad
- two duplicated homologous chromosomes (four chromatids) bound together by chiasmata during prophase I
- translocation
- the process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome
- trisomy
- an otherwise diploid genotype in which one entire chromosome is duplicated
- X inactivation
- the condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose