Human body cell → there is 1 pair of sex chromosomes and 22 pairs of non sex chromosomes called autosomes
- means that each human body cell has one pair of each type of chromosome.
- hence human body cells are diploid with 23 pairs of chromosomes. Meiosis Sexual Reproduction
In males → pair of sex chromosomes consists of 1 X chromosome and 1 shorter Y chromosome. Females → have pair of X chromosomes in each normal body cell.
During gamete formation → each gamete produces can only have 1 chromosome from each pair of chromosomes.
- in male → sperm produced contains either Y or an X chromosome.
- in female → each egg will contain one X chromosome
- Y chromosome shorter than X.
Random fertilisation will enable couple to have equal chances of producing boy or girl.
-
equal chances of male / female offspring
| Sex | Number of Chromosomes in Body Cells | Number of Chromosomes in Gametes |
|---|---|---|
| Male | 44 non sex chromosomes + X + Y | 22 non sex chromosomes + X or 22 non sex chromosomes + Y |
| Female | 44 non sex chromosomes + X + X | 22 non sex chromosomes + X |