Chapter 11, Problem 30A

Summary Introduction

To analyze:

The reason of trisomy and monosomy in humans are fatal.

Introduction:

Aneuploidies cells have abnormal copy number of chromosomes. The addition or loss of chromosome disturbs the equilibrium in cells. Monosomy is a type of aneuploidy in which the presence of only one chromosome from a pair. A trisomy is a type of aneuploidy in which three chromosomes copies instead of two normal chromosomes.

Explanation of Solution

In most cases, embryos with monosomy of sex chromosomes or autosomes are not viable. Some individuals with monosomy of sex chromosome can survive, such as Turner syndrome. Turner syndrome has one X chromosome instead of two normal sex chromosomes. A female show phenotypically but the gonads are sterilein this condition.

Example of Human diseases due to monosomy

1. Cri du chat syndrome- partial monosomy caused by a loss of the end of the short arm of chromosome number 5.

2. Turner syndrome- Turner syndrome have one x chromosome instead of two normal sex chromosomes.

Trisomies results can be a miscarriage, rather than live birth. For example, trisomy 16 is most common in human pregnancies. Usually, In this condition spontaneous miscarriage in the first trimester.

Trisomy 18 and trisomy 21 are the most common in which fetus with trisomy 13 can survive. Down syndrome is prone to the early appearance of Alzheimer's disease and this has a shortened lifetime. Trisomies of chromosomes 18 and 13 cause defects in the fetus. Some babies do not survive on birth and if born show mental retardation and other malfunction.

Types of trisomy are Trisomy 21 (down syndrome), Trisomy 13, Trisomy18, Trisomy 8, Trisomy 9, XXY ( Klinefelter syndrome), XXX, and XYY.