Chapter 5: 5.8 Inheritance of X-Linked Traits Flashcards
Define:
X-Linked traits
Traits are are present on the X chromosome
Why are X-linked recessive disorders more common in males than females?
Males only have one X chromosome
* This means that it would be impossible for a dominant allele to override the recessive allele
How many of her X chromosomes must be affected for a female to get a X-linked recessive disorder?
Both
True or False:
Males can be carriers for an X-linked recessive disorder
False, males can only be affected or unaffected
In X-linked Recessive:
How often are females affected?
Rarely affected, but can often be carriers
* Require both recessive alleles in order to be affected
In X-linked recessive:
How can females be affected?
- Both recessive alleles
- One recessive allele and the normal X chromosome is inactivated
In X-linked recessive:
Can two non-affected parents yield an affected male?
Yes
In X-linked recessive:
How can two non-affected parents can yield an affected male?
- The father is unaffected, meaning his X chromosome is normal
- The mother can be a carrier
In X-linked recessive:
Can two unaffected parents yield an affected daughter?
No
In X-linked recessive:
Why can’t two unaffected parents yield an affected daughter?
- Unaffected father means his X chromosome is normal
- This means no matter what, the daughter will have a normal chromosome
In X-linked dominant:
- Prevalence in family
- Occurrence
- Highly prevalent in the family
- Occurs twice as frequently in females as in males
True or False:
There are no carriers in X-linked dominant
True
In X-linked dominant:
Who will be affected if the father is affected?
- All daughters will have it
- Sons will never have it
In X-linked dominant:
Who will be affected with the mother is affected?
- Half of her sons
- Half of her daughters
What is an example of an X-Linked Recessive disorder?
Hemophilia, a blood clotting disorder
