Quiz 2 Flashcards
What are the three types of chromosomal mutations?
aneuploids
chromosome rearrangement
polyploids
aneuploids
alter the number of chromosomes
chromosome rearrangement
alter chromosome structure
duplication, deletion, inversion, translocation
polyploids
one or more additional sets of chromosomes
non-disjuction
failure of homologous chromosomes/sister chromatids to properly segregate
monosomy
loss of one member of homologous pair
trisomy
one additional member to homologous pair
non-disjunction in Meiosis I
all 4 gametes are abnormal
zygotes= 2n-1 and 2n+1
non-disjunction in meiosis II
2 normal gametes, and 2 abnormal
zygotes= 2n, 2n-1, 2n+1
Non-disjunction of autosomes
affects on large chromosomes= short lifespans
affects on small chromosomes= full lifespans
Mammalian Sex Chromosome
X and Y as pairing partners that normally segregate
imbalance in sex chromosome is less damaging than imbalance in autosomes
homogametic
XX
female
heterogametic
XY
males
SRY gene
sex-determining region on Y chromosome
Random X inactivation
only 1 X is in an active state
other Xs are inactive and condensed into Barr Bodies
Barr bodies
small darkly staining body in interphase cells of normal females
Changing copy number of a gene can cause…
unbalanced gene dosage
deletion
impact depends on what was deleted
duplication
human segmental duplications make up 4% of human genome
gives opportunity for evolution of new proteins
inversions
order of alleles changes, may lead to alteration in gene function/regulation
paracentric inversion
does NOT include centromere
pericentric inversion
includes the centromere
Translocations
movement of genetic material between nonhomologous chromosomes
two types:
- reciprocal translocations
- robertsonian translocations
reciprocal translocation
part of one chromosome exchanges with part of another chromosome