Consider a germ cell of a person with Down syndrome(Trisomy 21). Explain what is happening with the arrangement of chromosome 21 inside the cell during interphase 1, Anaphase 1, Telophase 1, telophase 11.

Please help, I am really stuck on this.

Thank you

http://www.mayoclinic.com/health/down-syndrome/DS00182/DSECTION=causes

Sure, I'd be happy to help!

During interphase 1, the cell is undergoing preparation for cell division. The arrangement of chromosome 21 is the same as in a non-Down syndrome individual. Chromosomes are duplicated during this phase and appear as sister chromatids, which are connected at the centromere.

During anaphase 1, the homologous chromosomes separate and move to opposite poles of the cell. In the case of Down syndrome, the extra copy of chromosome 21 does not separate correctly, resulting in one of the daughter cells receiving two copies of chromosome 21, while the other daughter cell receives no copy.

During telophase 1, the separated homologous chromosomes reach opposite poles of the cell, and the nuclear membrane starts to reform around them. The cytoplasm begins to divide and the cell prepares for the next division.

In telophase 2, the sister chromatids separate, and each is pulled towards opposite poles of the cell by the spindle fibers. The nuclear membrane reforms around each set of chromosomes.

It's important to note that the presence of an extra copy of chromosome 21 in Down syndrome is typically caused by non-disjunction during meiosis I, where two chromosomes fail to separate properly. This results in the production of gametes with abnormal chromosome numbers.

I hope this explanation helps! If you have any more questions, feel free to ask.