Question

Can you guys please fix this for me.

my project:

Monosomy is the absence of one chromosome from a paired chromosome. For example, Down’s syndrome which has more one chromosome at nubmer21. It makes 47 chromosomes totally. The trisomy reflects the presence of an extra chromosome to the cell. For example, in Turner’s syndrome person has one less X chromosome.

Non-disjunction is failure of cell division when chromosomes separation was occurring. If any chromosome get remains during the separation; means it does not split in two chromatids, it develops into non-disjuction and then non functional or dead cells.

My teachers comments for my project:

Be sure to include all parts of the research assignment.

Compare nondisjunction in meiosis I and II.

Include a more detailed description of one of the listed syndromes.

Answer 1

Let us define non disjunction in meiosis. Meiosis is the process of producing haploid gametes from a diploid cell. In case of normal division, chromosomes are separated evenly to produce four daughter cells with equal no. of chromosomes. However, if chromosomes fail to seggregate properly, it is termed as disjunction which results in aleuploidy of daughter cells. It occurs during anaphase of meosis I and II.

If non disjunction occurs during anaphase of meosis I, it would mean that one pair of homologous chromosomes were unable to separate. This would result in one pair of chromosomes having one extra pair of chromosomes and the other pair deficit of a pair of chromosomes.

If non disjunction occurs during anaphase of meosis II, it would mean that it would mean that one pair of cells would seggregate with normal pair of chromosomes and the other pair with abnormal pair of chromosomes. one of them would contain an extra pair of chromosomes while the other would be deficit of a set of chromosomes.

Down's syndrome is also known as trisomy 21. It is a genetic disorder which is caused by the presence of a third copy of chromosome 21. It is typically characterised by the delayed growth of a person, impaired intelluctual abilities, much lower IQ than a normal healthy person. They also have a decreased immune function and is prone to a large number of diseases including cardiovascular disease, thyroid disease, leukemia etc. Presence of a Robertsonian Translocation, or a ring chromosome also gives rise to this type of a condition. It is characterised by the karyotype 47, XX+21 for females and 47, XY+21 for males.