Lecture 17 Flashcards
1
Q
Why does X inactivation occur?
A
So that both males and females have the same number of genes as the X chromosome contains more genes than the Y chromosome.
2
Q
What is the Lyon Hypothesis?
A
- so both sexes have same no. of genes, X inactivation/lyonisation occurs
- one X chromosome in females is mostly inactivated
- early in development, random X chromosome is inactivated
- results in mosaicism in females
- equal no. of genes in males and females
3
Q
What are Barr bodies?
A
- inactivated X chromosomes condense into Barr bodies
- highly condensed structure that lies against nuclear envelope in female cells
- most genes not expressed as RNA synthesis cannot occur
4
Q
If someone had XXY chromosomes, would you expect to see Barr bodies?
A
Yes (only 1 X chromosome will be active)
5
Q
Most genetic diseases are found on this chromosome.
A
X
6
Q
Why are some genetic diseases more common in males over females?
A
Due to mosaicism, genes can more around and perform correct functions.
