For understanding about life and functions of different organs of body it is a must to understand about characteristic of chromosomes.
What is chromosome
The basic structure of life is cell. The cell contains what is called cytoplasm and nucleus. The cytoplasm contains the machinery to manufacture all the chemical ingredients to sustain the processes of life. Some cells aggregate to form tissues which aggregate to form organs. These organs eventually make the man. These are brain, heart, lungs, kidneys, liver, pancreas, spleen, reproductive organs like ovaries, uterus in females and testicles and penis in males. Thus a human body is constructed by a diverse structure of tissues and organs with the basic unit of the cells. Thus we see unity in diversity of life.The cytoplasm contains machinery to manufacture the chemicals to maintain life. It contains endoplasmic reticulum that contains ribosome to process the information transfer and mitochondria, the power plants of cells that supply energy. The nucleus contains rod like structure stainable with dyes called chromosomes. These chromosomes contain DNA, which is the store house of genetical information to be transmitted from generation to generation. The chromosomes occur in pairs or in sets. In man and woman there are 23 pairs, 22 sets are called autosomes and one pair which determines the sex of child. These chromosomes are designated as XX in woman and XY in man (fig. 14-15). [134]
Thus any male will have chromosomal constitution of XY and female XX. Sex is primarily determined by sex chromosomes X and Y at the time of fertilization of egg.