ch 8 variation in chromosome structure & number Flashcards
genetic variation
genetic differences among members of the same species or among different species
allelic variation
genetic variation in a population that involves the occurrence of two or more different alleles for a particular gene
cytogeneticist
a scientist who studies chromosomes under the microscope
metacentric
describes a chromosome with the centromere near the middle
submetacentric
describes a chromosome in which the centromere is slightly off the center
acrocentric
describes a chromosome with the centromere significantly off center, but not at the end
telocentric
describes a chromosome with its centromere at one end
G bands
the chromosomal banding pattern that is observed when the chromosomes have been treated with the chemical called Giemsa stain
deletion
condition in which a segment of DNA is missing
deficiency
condition in which a segment of chromosomal material is missing
duplication
the repetition of a segment of DNA more than once within a chromosome and/or within a genome
inversion
a change in the orientation of genetic material along a chromosome such that a segment is flipped or reversed from the normal order
translocation
- rearrangement in which one segment of a chromosome breaks off and becomes attached to a different part of the same chromosome
- event that occurs when a ribosome moves from one codon in an mRNA to the next codon
simple translocation
rearrangement in which one piece of a chromosome becomes attached to a different chromosome
reciprocal translocation
rearrangement in which two different chromosomes exchange pieces
terminal deletion
(also called see terminal deficiency) deletion in which a segment is lost from the end of a linear chromosome
interstitial deletion
(also called interstitial deficiency) deletion in which an internal segment is lost from a linear chromosome
repetitive sequences
short DNA sequences that occur many times within a species’ genome
nonallelic homologous recombination
recombination that occurs at homologous sites within chromosomes, where the sites are not alleles of the same gene; such misaligned crossovers are often due to the occurrence of repetitive spequences
gene duplication
an increase in the copy number of a gene; can lead to the evolution of gene families
gene family
two or more genes within a single species that are similar to each other because they were derived from the same ancestral gene
copy number variation (CNV)
a type of structural variation in which a segment of DNA that is 1000 bp or more in length commonly exhibits copy number differences among members of the same species
segmental duplication
a duplication in which a small segment of a chromosome has more than one copy if the same gene