Conclusion Of Down Syndrome

In the process of creating gametes, the cell undergoes meiosis where it produces four daughter cells from one parent cell. In order to proceed into meiosis, the cell must replicate its DNA and prepare for cell division during interphase. At this point, the cell would be called a diploid cell, because it contains two sets of chromosomes, one from the mother and the other from the father. Once the preparations are done, the cell enters prophase I where DNA supercoils to condense into chromosomes, and the chromosomes pairs up with its homologous chromosome. The process of pairing with its homologous chromosome in the chiasmata is called synapsis, which would result in the formation of a tetrad. At the point of chiasmata, there is a chance in which the chromosomes undergo crossing over where an exchange of genes between the two homologous chromosomes takes place. Then late in the prophase …show more content…
One of the nondisjunction is trisomy 21 or also known as Down’s syndrome. In 1866 John Langdon Down wrote a paper about Down syndrome, but only talked about the observable trait of this nondisjunction. Also the life expectancy at the year 1910 to those who had it, only live up to the age of 10 but in modern day, the life expectancy increased to the age of 60 depending on health problem and therapy. This nondisjunction occurs in anaphase I where the homologous pairs did not separate properly, leading to having an extra chromosome in two gametes and missing a chromosome in the others. In trisomy 21 case, an extra chromosome is found on chromosome 21 and thus causing cells to have difficulty in regulating the amount and type of protein that was made. Those with trisomy 21, exhibit a flat face with small broad nose and their ears are irregularly shaped. There are other distinguishable appearance for those who have trisomy 21 but these are the most