Final answer:
The statement that SRY is the female determining gene is false. SRY is critical for male sex determination in humans, and its presence on the Y chromosome initiates the development of male characteristics. In absence of a functional SRY gene, an embryo's undifferentiated gonads will develop into female reproductive structures.
Step-by-step explanation:
In humans, SRY is not the female determining gene; this statement is false. The SRY (Sex-determining Region of the Y chromosome) gene is actually responsible for the initiation of male sex characteristics. When the SRY gene on the Y chromosome is present and functional, it triggers the development of testes and male genitalia.
In contrast, the absence of a functional SRY gene, which is the case in XX females, leads to the development of female reproductive structures. Therefore, SRY is a critical factor in male sexual differentiation during embryonic development.
The SRY protein functions as a DNA binding protein and, together with another protein called SF1, acts as a transcription factor that activates certain genes that are essential in the development of the male sexual characteristics.
Any mutation resulting in a nonfunctional SRY protein or SF1 can impede the proper development of these male characteristics, leading to conditions such as Swyer syndrome, where an individual with an XY genotype may not develop expected male features.
During early embryonic development, without the influence of the SRY gene, everyone would develop female characteristics. This is due to the bipotential nature of the undifferentiated gonads, which can develop into either testes or ovaries. The presence of SRY gene promotes the development of testes by recruiting other genes and suppressing female developmental genes.