M6 Flashcards
define chromosomal instabilities
alteration of genome due to deletion, duplication or rearrangement of diploid chromosomal content
define non-disjunction
when homologous chromosomes (meiosis) or sister chromatids (mitosis) fail to segregate and migrate to opposit poles
number of chromosomes for trisomy
2n+1
Define monosomy
single copy of every gene
which ploidy has an associated risk for unmasking recessive alleles in heterozygote
monosomy
what best describes when an individual possesses only one functional allele (other is inactivate by mutation or monosomy)
haploinsufficiency`
a condition in which a cell or individual has more than 2 haploid sets of chromosomes
aneuploidy
polyploidy
translocation
deletion
polyploidy
define Autoploidy
duplication of a complete set of chromosomes
define alloploidy
combination of chromosome sets from different species (hybridization)
why are autotriploids rare?
they produce genetically unbalanced gametes
hybridization of species w/ different number of chromosomes can lead t sterility how is it possible for hybrid species to be fertile
if there is chromosome doubling
Why are most hybrids sterile
no homologous chromosomes for synpase
______ interferes with spindle formation resulting in no cell division and the cell re-enters interphase
cytokinesis
chromosome doubling
colchicine
mutation
colchicine
what happens if a cell doubles but doesnt divideI
It becomes bigger
endopolyploidy
only some cell of the organism are polyploid
what organs exhibit endopolyploidy and why
liver dues to cytokinesis failure
what happens if liver cell experience endopolyploidy
inc. metabolic activity, inc. size, tissue regeneration
may increase risk of mutation and cancer
define chromosomal rearrangement
breaking and insertion of two double stranded DNA molecule in a two different locations
what is one reason chromosomal deletion may occur in
during crossing over in meiosis
What percent of the genomes are copy number variations
5-10% ranging from 50bp to 3mB
the inverted segment INCLUDES the centromere is called
paracentric inversion or pericentric inversion
pericentric inversion
what is a dicentric referring to and what does it mean
two centromere (chromatid pulled at both sides and broke)
define inversion heterozygote
has an inverted and non-inverted chromosome
synapsis is impossible during meiosis without a what?
inversion loop
