125 Key Terms
- aneuploid
- individual with an error in chromosome number; includes chromosome segment deletions and duplications
- autosome
- any of the non-sex chromosomes
- centimorgan (cM)
- (also, map unit) relative distance that corresponds to a 0,01 recombination frequency
- Chromosomal Theory of Inheritance
- theory proposing that chromosomes are the genes’ vehicles and that their behavior during meiosis is the physical basis of the inheritance patterns that Mendel observed
- chromosome inversion
- detachment, 180° rotation, and chromosome arm reinsertion
- 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 crossing over
- karyogram
- a karyotype’s photographic image
- karyotype
- an individual’s chromosome number and appearance; 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 meiosis’ first cell division
- nonparental (recombinant) type
- progeny resulting from homologous recombination that exhibits a different allele combination compared with its parents
- paracentric
- inversion that occurs outside 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 progeny’s population
- translocation
- process by which one chromosome segment dissociates and reattaches to a different, nonhomologous chromosome
- trisomy
- otherwise diploid genotype in which one entire chromosome duplicates
- X inactivation
- condensing X chromosomes into Barr bodies during embryonic development in females to compensate for the double genetic dose
