Topic 6: Sex linked/ X Linked Inheritance Flashcards
1
Q
What is sex-linked or X linked inheritance?
A
- non-sexual inheritance determined by a gene on the X chromosome
2
Q
What are some examples of medical conditions resulting from sex-linked inheritance?
A
- hemophilia
- colour blindness
- Duchenne’s muscular dystrophy
3
Q
What are sex linked inheritance diseases caused by?
A
- recessive alleles on the x xme
4
Q
What does XY mean in terms of x-linked inheritance? (2)
A
- not truly homologous
- if gene is x-linked, its expression is not masked because no corresponding allele on Y
5
Q
What does XX mean?
A
- homologous
ex. colour blindness
6
Q
Using colour-blindness as an example, what are the possible parental GENOTYPES for XX? (3)
A
X^NX^N
X^NX^n
X^nX^n
- remember that anything X^X^ is female because males have a Y xme
7
Q
What would the phenotype be for XNXN?
A
“normal” homozygous dominant
8
Q
What would the phenotype be for XNXn? (2)
A
- “normal” but carrier
- heterozygous
9
Q
What would the phenotype be for X^NY?
A
“normal”
10
Q
What would the phenotype be for X^nY? (2)
A
- Would have illness (colourblind)
- no gene on Y to mask recessive gene
