Answer:
Aneuploidy is a phenomenon which occurs due
to non-disjunction, resulting in gain or loss of one or more chromosomes during
meiosis.
Aneuploidy is different from polyploidy.
Polyploidy is a phenomenon in which the organisms contain more than two
monoploid value or basic sets of chromosomes, i.e., -3n, 4netc.
Example of such organisms are
certain fish and salamanders and is commonly found in plants like grapes,
banana.
Chromosomal Abnormalities
(a) Down's syndrome is an
autosomal disorder that is caused by the trisomy of chromosome 21.
The individual is short statured
with round head, open mouth, protruding tongue, short neck, slanting eyes, and
broad short hands. The individual also shows retarded mental and physical
growth, under developed gonads and genitats, etc.
(b) Klinefelter's syndrome is
the chromosomal disorder that is caused by the presence of an additional copy
of X-chromosome resulting in the karyotype 45+XXY
In this disorder sex of the
individual is masculine but possess feminine characters also .The individual
shows gynaecomastia, i.e., development of breasts. The individual will be often
sterile having poor beard growth and feminine pitched voice.
(c) Turner's syndrome is the
chromosomal disorder that is caused by the absence of one of the X-chromosomes,
resulting in the karyotype 45+XO.
In this disorder the individual (female)
will be sterile with rudimentary ovaries. Other symptoms include shield-shaped
thorax, webbed neck, poor development of breasts ,short stature, small uterus
and puffy fingers.
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