Lifesci 2G03 - Test 2 Questions and
Answers Fall 2024 with complete Solution;
McMaster University
at what age does a drastic decline in fertility occur? - ANSWER-
35
what 2 events tend to happen at age 35 in women? - ANSWER--
increased rate of spontaneous abortions
-eggs accumulate with chromosomal abnormalities
monosomy formula and definition - ANSWER--2n-1, in humans
45 total chromosomes
-missing one chromosome from a pair
nullisomy formula and definition - ANSWER--2n-2
-missing a pair of homologous chromosomes
disomy formula and definition - ANSWER--2n+2
-an extra pair of chromosomes
,trisomy formula and definition - ANSWER--2n+1
-one extra chromosome
what specific aneuploidies become more common with
increasing maternal age? - ANSWER-trisomy 21, 18, and 13
common traits of down syndrome - ANSWER--mental
retardation
-heart defects
-hearing deficits
-skeletal abnormality
-susceptibility to infection
what is one reason why trisomy 21 is the most common
trisomy? - ANSWER--because fetuses affected by other
trisomies often do not reach birth or are stillborn
-most "viable" trisomy
meiosis *ON THE TEST* - ANSWER-a type of cell division in
germ cells whereby a single germ cell divides to produce four
non-identical daughter cells with half as many chromosomes
,difference between meiosis I and meiosis II - ANSWER--in
meiosis I, genetic material is exchanged between NON-sister
chromatids (homologous chromosomes) with non-identical
DNA.
-in meiosis II, no crossing over occurs and cell division happens
without DNA duplication, forming 2 haploid gametes.
chromosome disjunction + when in meiosis it may occur -
ANSWER--failure of homologous chromosomes to separate in
meiosis I
-failure of sister chromatids to separate in meiosis II
-happens during anaphase I and II
gametes that will occur if nondisjunction happens in meiosis I
(autosomes) - ANSWER-n+1, n+1, n-1, n-1
gametes that will occur if nondisjunction happens in meiosis II
(autosomes) - ANSWER-n+1, n-1, n, n
what do we get if we fertilize a normal sperm with a monosomy
or a trisomy? - ANSWER-2n-1 and 2n+1
, how can you differentiate between meiosis I and II
aneuploidies? - ANSWER--nondisjunction in meiosis I:
heterozygous gametes at the centromeric region
-nondisjunction in meiosis II: homozygous gametes at the
centromeric regions (means that sister chromatids haven't been
pulled apart)
how many different types of nondisjunction gametes are there
for Y chromosomes - ANSWER-3
what are the 3 ways that disjunction can happen in XY
individuals? - ANSWER-1. nondisjunction in meiosis I
2. nondisjunction in meiosis II, where the X chromosomes
separate normally and the Y stay together
3. nondisjunction in meiosis II, where the Y chromosomes
separate normally and the X stay together
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