Question

A woman with 47 chromosomes due to three copies of chromosome 21 is characterized by
A.Down syndrome
B.Triploidy
C.Turner syndrome
D.Super Femaleness

Answer 1

Chromosomes are thread-like structures present within the nucleus that carry hereditary information within the salt of genes which are passed from parents to offspring. Down syndrome or Mongolism is by far the most common and best known as chromosome disorder. It is primarily caused by the presence of all parts of the third copy of chromosome 21.

Complete answer:
Every species features a characteristic structure and number of chromosomes present. Due to certain irregularities at the time of cell division, alteration in the structure or number of chromosomes may happen. Even the slightest alteration can lead to various abnormalities. Changes in one chromosome part ,whole chromosome or chromosomal sets are known as “chromosome aberrations”.
There are 46 chromosomes in each human cell present as 23 pairs out of that ,22 are autonomous and one is sex chromosome. Chromosomal disorders are caused due to structural changes for numerical changes in chromosomes. Down syndrome is the best known chromosomal disorder in humans and most common cause of intellectual disability. It is primarily caused by trisomy of chromosome 21 and this is the most common trisomy among live birth. It is characterized by certain birth defects, learning problems and facial features. Like other chromosomal disasters trisomy 21 also gives a race to multiple Systemic complications as part of clinical syndrome. The chromosomal disaster leads to both structural and functional defects in patients with down syndrome. A child suffering with down syndrome also may have heart defects and problems with hearing and vision.
The presence of full or partial extra 3 copies of chromosome 21 causes down syndrome. It is called trisomy 21 and is represented as 45+ XY or 45+ XX. The absence of one X-chromosome causes turner’s syndrome. Turner syndrome can be represented as 44 + X0. Triploidy is marked by the presence of three complete sets of haploid sets of chromosomes and is represented as 3n where, “n” denotes the haploid set. The presence of one or more extra X chromosomes in females causes super femaleness and it is denoted by 44 +XXX.

Hence the correct answer is option(A)

Note: Down syndrome trisomy 21 or mongolism, is a congenital disorder caused by the presence of Human Genome of extra genetic material from chromosome 21. Here ,the affected individual may transmit an extra part of chromosome 21 or an entire copy of chromosome 21.