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

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Biology 2e Part I, 2nd edition Copyright © 2022 by LOUIS: The Louisiana Library Network is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted.

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