Question

Trisomy X typically does not cause phenotypic abnormalities because ______.

Multiple choice question.
the X chromosome contains genes that are not essential for survival
all additional X chromosomes are converted to polar bodies
all additional X chromosomes are converted to Barr bodies
the X chromosome is very small and does not contain a lot of genes

Answer 1

Trisomy X does not typically cause phenotypic abnormalities due to X inactivation, a process where one X chromosome in each cell of a female embryo is inactivated, compensating for the extra X chromosome.

Step-by-step explanation:

Trisomy X typically does not cause phenotypic abnormalities because of a process called X inactivation. During early development, one X chromosome in each cell of a female mammalian embryo inactivates by condensing into a structure called a Barr body. The genes on the inactive X chromosome are not expressed. By this process, females compensate for their double genetic dose of X chromosome, which explains why trisomy X does not typically result in significant phenotypic abnormalities.