Final answer:
The SRY gene is located on the Y chromosome, not the X chromosome, and it is this gene that is essential for the development of male sex characteristics. It activates the development of testes and male genitalia while suppressing genes important for female development. A functional SRY gene is crucial for a male development pattern; its absence leads to female development.
Step-by-step explanation:
The statement that the SRY gene is a gene of the X chromosome that controls the development of gonads and external genitalia is false. The SRY (Sex-determining Region Y) gene is located on the Y chromosome, not the X chromosome. This gene is crucial for initiating the development of male sex characteristics in humans and many other mammals. In the absence of a functional SRY gene, the default developmental pathway of the embryo's gonads is to become ovaries, leading to the formation of female sex characteristics.
During human embryonic development, the SRY gene on the Y chromosome instigates a cascade of genetic events that causes the bipotential gonadal tissue to differentiate into testes, which then produce testosterone. Testosterone is the hormone responsible for the development of male genitalia and secondary sexual characteristics. On the other hand, if the SRY gene is deleted or mutated, this could result in a condition known as Swyer syndrome, in which an individual with an XY genotype develops as a female.
Furthermore, the SRY gene in males recruits other genes to begin the development of the testes and suppresses genes that are important for female development. Together with the protein SF1, the SRY protein acts as a transcription factor that turns on certain genes necessary for male sexual development. Without the action of the SRY gene, germ cells in the bipotential gonads differentiate into oogonia and primordial follicles develop in the primitive ovary, leading to female development.