Sex and Autosomes Chromosomes

Sex chromosomes determine the sex of an organism. A human somatic cell has two sex chromosomes: XY in males and XX in females. A human germ cell has one sex chromosome X or Y in a sperm and X in an egg. When X-sperm is combined with an egg, the resulting zygote (fertilize egg) will contain two  X chromosomes. A person developed from XX-zygote will have the characteristics of females. Combination of an Y-sperm and an egg will produce a male.

The SRY gene

Usually, a women has two X chromosomes (XX) and a men one X and one Y (XY). However both male and female can be characteristics can sometimes by found in one individual, and it is possible for a women to have XY and a men to have XX. Analysis of such individuals has revealed some of the molecules involved in sex determination, including one called that is very important for testing information.

SRY which stands for (sex determining region Y gene) Is found in the Y chromosome. In the cell, it binds to other DNA and in doing so distorts it dramatically out of shape. This alters the properties of DNA and likely alerts the expression of a number of genes, leading to testing formation. Most XX men who lack a Y chromosome do still have a copy of SRY gene on one of their X chromosomes (moved by a chromosomal trans-location) This copy accounts for their maleness. However, because the remainder of the Y chromosome is missing they frequently do not developed secondary sexual characteristics in the usual way.

The nucleic of humans have 22 autosomes which are responsible for body characteristics. Autosomes are numbered roughly in relation to their size. For example, chromosome 1 has approximately 2,800 genes, while chromosome 22 has approximately 750 genes.