Sections
Key Terms
Key Terms
- aneuploid
- individual with an error in chromosome number; includes deletions and duplications of chromosome segments
- autosome
- any of the non-sex chromosomes
- centimorgan (cM)
- (also, map unit) relative distance that corresponds to a recombination frequency of 0.01
- Chromosomal Theory of Inheritance
- theory proposing that chromosomes are the vehicles of genes and that their behavior during meiosis is the physical basis of the inheritance patterns that Mendel observed
- chromosome inversion
- detachment, 180° rotation, and reinsertion of a chromosome arm
- euploid
- individual with the appropriate number of chromosomes for their species
- homologous recombination
- process by which homologous chromosomes undergo reciprocal physical exchanges at their arms, also known as crossing over
- karyogram
- photographic image of a karyotype
- karyotype
- number and appearance of an individuals chromosomes; includes the size, banding patterns, and centromere position
- monosomy
- otherwise diploid genotype in which one chromosome is missing
- nondisjunction
- failure of synapsed homologs to completely separate and migrate to separate poles during the first cell division of meiosis
- nonparental (recombinant) type
- progeny resulting from homologous recombination that exhibits a different allele combination compared with its parents
- paracentric
- inversion that occurs outside of the centromere
- parental types
- progeny that exhibits the same allelic combination as its parents
- pericentric
- inversion that involves the centromere
- polyploid
- individual with an incorrect number of chromosome sets
- recombination frequency
- average number of crossovers between two alleles; observed as the number of nonparental types in a population of progeny
- translocation
- process by which one segment of a chromosome dissociates and reattaches to a different, nonhomologous chromosome
- trisomy
- otherwise diploid genotype in which one entire chromosome is duplicated
- X inactivation
- condensation of X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose