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Down’s syndrome is caused due to
Down’s syndrome is caused due to
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Solution
The correct option is D trisomy of 21st chromosome
Human beings are diploid and have two sets of chromosomes in all the somatic cells.
The diploid number of chromosomes in human beings is 46 and the haploid number is 23 (in gametes).
But due to abnormal cell division during the development of the gametes, the number of chromosomes in the gametes might be more or less than 23 chromosomes.
Such gametes with abnormal number of chromosomes involved in fertilisation produce zygote which will not have 46 chromosomes.
Lack or extra copies of one or few chromosomes in the zygote leads to chromosomal disorders.
One such chromosomal disorder is Down’s syndrome.
Down’s syndrome is a chromosomal abnormality in humans in which the affected individuals (can be males or females) have three copies of the 21st chromosome instead of two copies.
This condition is called trisomy (2n+1) of the 21st chromosome.
The individuals affected with Down’s syndrome have 47 chromosomes.
The karyotype is represented as 47, XX, + 21 for females and 47, XY, + 21 for males.
Trisomy of X chromosome is a condition in which the affected females have three X chromosomes instead of normal two copies of X chromosome. It is also known as triple X syndrome or XXX syndrome.
Monosomy in human beings refers to lack of a single chromosome within the diploid set.
It is represented as 2n-1. The affected individuals have 45 instead of 46 chromosomes.
Turner's syndrome is a chromosomal abnormality in which there is a lack of one of the X chromosomes in females (Monosomy X). Affected females are sterile.
Trisomy of the 18th chromosome leads to Edwards syndrome in human beings. It is also a chromosomal abnormality.
Human beings are diploid and have two sets of chromosomes in all the somatic cells.
The diploid number of chromosomes in human beings is 46 and the haploid number is 23 (in gametes).
But due to abnormal cell division during the development of the gametes, the number of chromosomes in the gametes might be more or less than 23 chromosomes.
Such gametes with abnormal number of chromosomes involved in fertilisation produce zygote which will not have 46 chromosomes.
Lack or extra copies of one or few chromosomes in the zygote leads to chromosomal disorders.
One such chromosomal disorder is Down’s syndrome.
Down’s syndrome is a chromosomal abnormality in humans in which the affected individuals (can be males or females) have three copies of the 21st chromosome instead of two copies.
This condition is called trisomy (2n+1) of the 21st chromosome.
The individuals affected with Down’s syndrome have 47 chromosomes.
The karyotype is represented as 47, XX, + 21 for females and 47, XY, + 21 for males.
Trisomy of X chromosome is a condition in which the affected females have three X chromosomes instead of normal two copies of X chromosome. It is also known as triple X syndrome or XXX syndrome.
Monosomy in human beings refers to lack of a single chromosome within the diploid set.
It is represented as 2n-1. The affected individuals have 45 instead of 46 chromosomes.
Turner's syndrome is a chromosomal abnormality in which there is a lack of one of the X chromosomes in females (Monosomy X). Affected females are sterile.
Trisomy of the 18th chromosome leads to Edwards syndrome in human beings. It is also a chromosomal abnormality.
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