Genetic Counseling - Understanding The Pattern Of Genetic Inheritance
A Normal human being has 46 chromosomes in 23 pairs. Each of the trillion of human cells have 23 pairs of chromosome in the nucleus. Twenty two pairs of chromosomes are called Somatic chromosomes and the 23rd pair is called 'Sex chromosomes'. The sex chromosomes are different in males and females. A female will have a pair of XX chromosome and a Male will have XY chromosome. The 23 pairs of Chromosomes carry the three billion genes in each cell.
We normally inherit one chromosome unit of each pair from one parent. Interestingly the ova and sperm that fuse and form the first cell when fertilization takes place only has 23 chromosomes each and on fusion make up the 46 chromosomes in the fertilised egg in the mother’s womb. The one X – Chromosome in male will always come from the mother and Y will be from the father. In females one X each will come from each parent.
