X-chromosome inactivation Flashcards
How can males and females both have the same level of gene expression even with a different amount of X chromosomes?
Females undergo X chromosome inactivation, so each sex only has one X chromosome expressing genes
How are X chromosomes inactivated?
They become highly condensed
What is the name of the inactivated X chromosome?
A Barr body
What determines which X chromosome gets inactivated in females?
Nothing, it is completely random
How does X chromosome inactivation affect the phenotype of X-linked genes?
Females can be a mosaic depending on which chromosome becomes inactivated and inherited by all the daughter cells through mitosis
What happens with this in heterozygotes?
Either allele can show. Whichever one continues expressing genes will be passed on to the daughter cells through mitosis and results in patches of colour
Why can’t male cats be calico?
They only have one X chromosome, so they can only be orange or black
What has to be the genotype of a female cat for her to be calico?
She has to be heterozygous. Homozygous will result in being either orange or black
