Biology Questions and Answers
syndrome, trisomy 18, 45 + XY or 45 +
XX).
- In general what is the
cause of the aneuploidies?
Generally thby impaired assortmee aneuploidies are causnt of ed
chromosomes during meiosis. For
example, chromosomes owhen the homologousf the pair 21 do not (^)
separate gametes with two
chromosomes 21 chromosomes 21 and gametes withoform. If a gamete withut (^)
two chromosomes 21 fecundates a
normal gamzygote will present trisomyete of the opposite sex the (three
chromosomes 21). If a gamete without
chromosomes 21 gamete of the opposite sex thfecundates a normalere will be (^)
a zygote with mochromosome 21).nosomy (with only one
The defects in tchromosomes dhe separation ouring cell division arf (^) e
called chromosomal nondisjunctions.
During meiosis nondisjunctions mayoccur in the anaphase I (nondisjunction (^)
of homologous) as well in anaphase II
(nondisjunction of sister chromatids).
- Do all genetic diseases
result from alteration in the
number of chromosomes of
the cells?
Besides aneuploidies there are other
genetic diseases, otabnormalities and also thher chromosomale genetic
mutations.
- How are genetic diseases
classified?
Genetic diseases classify into
chromosomal abmutations. normalities and genetic
Among chromosomal athere are the aneuploidies, diseasbnormalitieses (^)
caused by alterations of the normal
(euploidy) nthe species. An example of aneuploidy isumber of chromosomes of (^)
Down syndrome, or trisomy 21, in which
there are three chrominstead of the normal pair. In the grouposomes 21 (^)
of chromosomal abnormalities there are
also thchromosome), e deletions (absence of part of athe inversions (in which
a chromosome breaks and its pieces
reconnect in inverse translocations (pieces of manner) and thea chromosome (^)
that exchange positions).
In the genetic mutation group there are
the deletions (one or more DNAnucleotide absent), the substitutions (^)
and the insertions.
- What are genetic
mutations?
Genetic mutations are alterations of the
genetic materialnormal condition o (comparf the species)ed to the
involving modifications in the normal
nucleotidwithout structurale sequence of a gene but or numeric
chromosomal changes.
These modifications(loss of nucleotides), substitutions may be deletions
(exchandifferent nucleotides) oge of nucleotides by otherr insertions (^)
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