Sex Determination

A particular nuclear arrangement was perceived by Henking. He perceived that this particular nuclear arrangement was found in only fifty per cent of sperms. He termed this body as x. Later, it was observed that the ova which only obtained the X chromosome matured and were born as females and those that didn’t receive only X chromosomes were born as males. Thus, the X- chromosome was termed a sex chromosome and the remaining ones were termed autosomes.

The occurrence due to which a modification in DNA happens and causes a variation in the phenotype and genotype of a creature is termed a Mutation.

Genetic Disorders

Disorders of a Mendelian nature include:

• Haemophilia.
• Sickle Cell Anaemia.
• Phenylketonuria.

Disorders of a chromosomal nature include:

• Down’s syndrome.
• Klinefelter’s Syndrome.
• Turners Syndrome.