Numerical aberrations: Aneuploidy and polyploidy Flashcards
Normally, human somatic cells contain _____ and are termed diploid (as the number is twice the haploid number of 23 as found in gametes).
46 chromosomes
A chromosome number that is an exact multiple of the haploid number and exceeds the diploid number is called _____, and one that is not an exact multiple is called _____.
polyploidy; aneuploidy
Aneuploidy usually arises from the failure of paired chromosomes or sister chromatids to disjoin at anaphase a process called ____.
non - disjunction
Aneuploidy may be due to delayed movement of a chromosome at anaphase a process called ____.
Anaphase lag
T/F. In either non-disjunction, and anaphase lag, two cells are produced, one with an extra copy of a chromosome (trisomy) and one with a missing copy of that chromosome (monosomy).
True
The cause of meiotic non - disjunction is not known. Nevertheless, what are factors that seem to increase the frequency of meiotic non-disjunction?
Increasing maternal age
Maternal hypothyroidism
Irradiation
Viral infection
Familial tendency
Meiotic non-disjunction is also associated with a ____.
reduced frequency of recombination
The cause of mitotic non-disjunction is also not known, but it has been associated with altered expression of proteins involved either in ____ or ____.
kinetochore-microtubule attachment
spindle assembly checkpoint
Trisomy of chromosome 13, 18 or 21 (in addition to sex chromosome aneuploidy, if required) can be detected prenatally, without the need for prior cell culture using what techniques?
FISH
QF-PCR
In this increasingly used technique, which can be completed in a few hours, the signal intensity of several chromosome - specific marker PCR products are compared with each other.
QF-PCR
QF-PCR is achieved using ____ with fluorescent oligonucleotide primers and subsequent detection using an automated DNA sequencer w/ dedicated software.
multiplex PCR reactions
T/F. Aneuploidy can arise during either meiosis or mitosis, as mentioned above, and meiotic non - disjunction may occur at either the first or the second meiotic divisions.
True.
T/F. If non - disjunction occurs at the first meiotic division, then the gamete w/ the extra chromosome will contain both (non -identical) homologues of that chromosome, whereas if it occurs at the second division then the normal and the extra copy of that chromosome will be identical.
True
T/F. Sometimes the origin of the non-disjunctional event can be determined from the knowledge that two alleles at one locus are contributed by one parent, or by analysing the inheritance of chromosomal or DNA polymorphisms.
True
T/F. Complete failure of synapsis of a pair of parental homologues at first meiosis (non-conjunction) may also lead to aneuploidy, and this is revealed by a total lack of ____ between parental loci.
recombination
