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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 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 |
meiosis I | the first round of meiotic cell division; referred to as reduction division because the resulting cells are haploid |
meiosis | a nuclear division process that results in four 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 |
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 |
Xinactivation | the condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose |
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