Answer
Down
syndrome is an example of aneuploidy. There is an abnormal number of
autosomes.it is a results of non-disjuction during meiosis. The two chromosomes
number 21 fails to separateduring anaphase I or anaphase II of meiosis. The
gametes produced contain 24 chromosomes (two copies of chromosome 21) and 22
chromosomes ( no chromosomes 21). When a sperm cell containing 23 chromosomes
fuses with an ovum contaning 24 chromosomes, the zygote formed contains trisomy
21 (three chromosomes 21).
The
induviduals with trisomy 21 may be males or females. They have flat, broad
faces, slanted eyes with skin folds in the inner corner, protuding tongue,
short palms, hanging mouth, wide nose and are mentally retarded. They usually
have congenital heart defects, reduced resistance to diseases and a shortened
lifespan.
Assignment submitted by L.Y., Kong, S. H., Lim, S. C., Soo, C. W.
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