The difference between two individuals of same species with respect to heredity is known as . So, an individual can either be a male or female in normal circumstances. Scientists have discovered that is transmitted by definite - chromosomes, also called heterosomes. The human body cells have two chromosomes. A woman has two X- chromosomes while a man has one X- chromosome and one Y-chromosome.
Therefore, an egg cell has one X- chromosome and a ** cell has either an X- or a Y-chromosome. This means that the of a baby is determined by the type of cell fertilizing the egg. If an egg, fused with a having Y-chromosome, then the male zygote will develop and when fused with ***** having X-chromosome then a female zygote will develop.
In human beings, there are 23 pairs of chromosome. Out of these 22 chromosomes pairs are called autosomes and the last pair of chromosomes that helps in deciding gender of a individual is called *** chromosome.
Female - 22 pairs(autosomes) + XX (*** chromosomes)
Male - 22 pairs (autosomes) + XY(*** chromosomes)
During gamate formation female always donates 'X' chromosomes, whereas a male donates either 'X' or 'Y' chromosome. Therefore the *** of the child depends on the type of chromosome donated by male.
44 + XY = boy, 44 + XX = girl
Evolution is defined as any genetic change in a population that is inherited over several generation.
