Chapter 15: Chromosomal Basis of Inheritance Flashcards
Hemophilia
A sex-linked recessive trait defined by the absence of one or more clotting factors
Home it’s more likely for men to have hemophilia that women?
It’s on the X chromosome. Since women have 2 X chromosomes, they can be carriers of hemophilia, but not have it. Women require both mother and father to provide the recessive hemophilia to gain it. Men however only get when X from mom, and are hemizygous. So, if there mom passes on the X with the hemophilia they will gain hemophilia.
X - inactivation
Female mammals inherit 2 X chromosomes. 1 X chromosome becomes inactive during embryonic development
Barr Body
The inactive X condense into compact object. During embryonic development of x- inactivation
How does the egg chose which X becomes the Barr Body?
The X that becomes the Barr body is random
Where are genes found?
On sex chromosomes discovered by T.H. Morgan
How many sex chromosomes are there in humans and mammals?
2 for humans X & Y
XX: develops female, gene redundancy, like autosomal chromosomes
XY: develops male, no redundancy
What is on the Y chromosome
Few genes other than SRY
SRY
It is the sex determining region on the Y it turns on the genes for the male hormones
many effect= pleiotropy
What is on the X chromosomes?
other gene/traits beyond sex determination
mutations on X
- hemophilia
-Color blindness
Sex- Linked
Usually means X-linked, any diseases on Y is called Y-linked
more than 60 diseases on the X chromosomes
Autosomal Traits are influenced by what hormones?
Sex hormones
Gene Imprinting
the process by which only one copy of a gene in an individual (either mother or father) is expressed, while the other copy is suppressed.
X Imprinting
one of the X chromosomes “shut down” for females
Are most genes biallelic or monoallelic
Biallelic
Mom Gene –> protein Dad gene –> protein
