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Biology

Key Terms

BiologyKey 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
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