Part K: Lecture 42 Flashcards
euploid (def.)
cell/organism with complete chromosome set
euploid can be ___ or ____ or ___ etc.
haploid
diploid
triploid
aneuploid (def.)
cell/organism with tooo many or too few of one chromosome
aneuploid examples
monosomic (2n-1)
trisomic (2n+1)
monosomic (def.)
one less chr
trisomic (def.)
one more chr
causes of aneuploidy (3)
1) failure during anaphase (microtubules don’t properly pull chr apart)
2)non-disjunction during mitosis
c)non-disjunction during meiosis I or II
non-disjunction (def.)
the failure of homologous chromosomes or sister chromatids to separate properly during cell division
non-disjunction during mitosis: # of aneuploid cells
two (2)
non-disjunction during meiosis I: # of aneuploid cells
four (4)
non-disjunction during meiosis II: # of aneuploid cells
two (2)
triploid ≠ trisomic why?
triploid: three copies of each chr - non viable in humans
trisomic: three copies of one chr
cells work best when there are how many copies of each gene? why?
two (2)
balance in amount of proteins
2 consequences of aneuploidy
-monosomy
-trisomy
monosomic cell –> _____ —> _____ proteins –> _____
gene imbalance
too few
cell dies
trisomic cell –> _____ —> _____ proteins –> _____
gene imbalance
too many
cell dies
monsomy vs trisomy: which is worse?
monosomy (greater imbalance)
aneuploidy is common in ___
embryos (1/3)
aneuploidy is rare in ___
infants
aneuploidy can be viable if chromosome is ____ (3)
small (Chr 21)
has few genes (Y)
can be inactivated (X)
maternal age effect (def.)
age of mother increases chances of aneuploidy
reason for maternal age effect: ___
oogenesis begins in female fetus and arrest in prophase I
↑ time in meiosis = ↑ nondisjunction
sex chromosome aneuploidy is usually fixed by ___
dosage compensation (count X chr, turn off all but one)
sex chromosome aneuploidy: gene in pseudoautosomal region ____
remains active even in inactivated X chr
2 x chr = ___ barr bodies
1
3 x chr = ___ barr bodies
2
1 x chr = ___ barr bodies
0
euploid male and female # of chr
46 chr
