Question

Write short note on sex determination in humans.

Answer 1

Hint: The male produced two types of cells with both X and Y chromosomes and the females produce only those with X. So, sex is determined by chromosomal factor and male parent is mainly responsible for the gender of the offspring.

Complete answer:
Sex determination is a process in which the sexual characteristics of an organism or offspring is found. It helps to determine the sex of the offspring, whether it is male or female. The most commonly used technique is chromosomal sex determination. In humans, XX XY type of sex determination is found, it is also found in other mammals and some insects. A human contain total 46 chromosomes, 44 autosomes and 2 sex chromosomes. These two sex chromosomes determine the sex of the offspring.

When a male and female gametes fuse, a zygote is formed. These gametes contain chromosomes, gametes are haploid and the gametes contain 23 chromosomes. The female have two sex chromosomes, which are two X chromosomes.

The gamete is formed by meiosis, so the female gamete will have 22+X chromosomes and in male 2 sex chromosomes are found: X and Y. So, the male gamete will have either 22+X or 23+Y. When the Y chromosome is present in the male gamete and it fuses with the X chromosome of the female, a male zygote is formed with 44+XY chromosome. When the X chromosome is present in the male gamete and it fuses with the X chromosome of the female, a female zygote is formed with 44+XX chromosome.

Note: In the XY sex-determination system, the female always provide X chromosome and the male provides either an X chromosome or a Y chromosome and they fuse to form female (XX) or male (XY) offspring, respectively. The ratio of chromosomes X or Y are determined by the hormone levels in the male parent.