Sex linked traits and pedigrees Flashcards
1
Q
The Y chromosome
A
- Fewer then two dozen genes identified
- One is the master gene for male sex determination (SRY gene)
- SRY present, testes form
-SRY absent, ovaries form
2
Q
The X chromosome
A
-Carries more than 2,300 genes
-Genes on X chromosome can be expressed in both males and females
3
Q
Sex linked traits
A
Traits located on sex chromosomes are called sex-linked traits and are usually on the X chromosome
ONLY FOCUSING ON RECESSIVE X LINKED TRAITS
4
Q
Sex linked traits and males
A
- A recessive trait located on the X chromosome is more likely to be expressed in males since they need only one copy of the recessive allele while females need two
- Recessive X-linked disorders occur more frequently in males(hemophilia,pattern baldness, colour blindness)
SON CANNOT INHERIT DISEASE FROM HOS FATHER
5
Q
Y linked disorders
A
Disorders where the allele is located on the Y chromosome and passed on from father to all of his sons
6
Q
Notations
A
XX for females
XY for males
Dominant allele is capitalized with superscript
Recessive allele is lowercase and written as a superscript