Question

How is aneuploidy different from polyplodidy ?What are the mechanisms by which aneuploidy and polypeptide are caused,and what are the consequences of these chromosomes alterations in terms of survival and fertility of the offspring?

Answer 1

aneuploidy	polyploidy
The presence of an abnormal number of chromosomes in a cell is referred to as the aneuploidy	The Consisting of more than two homologous chromosome sets in a cell is referred to as polyploidy
occurance in human quite common	very much rare in humans, but more common in ferns and flowering plants
Aneuploidy has different terminologies such as nullisomy, monosomy, disomy, trisomy and tetrasomy	Polyploidy has different types like Triploid, Tetraploid, Hexaploid, Octaploid, Dodecaploid
mostly chromosomal disorders. Some of disorders are lethal	Triploid and tetraploid situations in human are lethal.

aneuploidy

• During the process of producing gametes, improper segregation of chromosomes between the cells is the inception for aneuploidy.
• aneuploidy can be divided into two: autosomal disorders and sex chromosome disorders.
• During meiosis, homologous pairs are segregated into each cell one by one. The two sex chromosomes are also segregated to two daughter cells. But, some pairs still remain unsegregated and located in one gamete. The resulting one gamete thereby contains extra chromosome whereas the other is missing a chromosome.

example

Nullisomy:              2n­2 Lethal condition in humans

Monosomy:            2n­1 Sex chromosomal disorder – Turner syndrome (45+X)

Disomy:                  n+1 Disomy causes aneuploidy in triploid or tetraploid organisms.

Trisomy:                2n+1 Autosomal disorders – Trisomy 16 (miscarriage in the fetus),

                             Trisomy 21 – Down syndrome, Trisomy 18 – Edwards syndrome, Trisomy 13 –Patau syndrome.

                           Sex chromosomal disorders – 47+XXX, Klinefelter syndrome (47+XXY) and 47+XYY

Tetrasomy/ Pentasomy:     2n+2 or 2n+3 Sex chromosome disorders – XXXX, XXYY, XXXXX, XXXXY and XYYYY

polyploidy

Polyploidy may occur due to abnormal cell division, either during mitosis, or commonly during metaphase I in meiosis.

Polyploidy is more common in plants then human ,since we are only discussing its impact in humans,so the Polyploidy can be found in the tissue formation of  liver,heart ,bone marrow and the placenta.

although most of the times, polyploidy in humans end up with miscarriage.