Classic Mendelian Genetics II Flashcards
Martin - week 3 lect 1
In veterbrates, what does the gonad have the potential to develop into?
either a testis or an ovary
homomorphic?
female has the genotype XX
heteromorphic?
male has genotype XY
Describe the difference between the X and Y chromosome:
X chromosome is larger and longer than the Y chromosome
What are the designated sex chromosomes in birds?
Z and W
male genotype in birds?
homomorphic - ZZ
female genotype in birds?
heteromorphic (ZW)
What is the sry?
sex-determining region of the Y chromosome (a single gene)
Sry expression…
testes –> testosterone –> masculine brain phenotype
No sry expression…
Ovaries –> relatively low testosterone –> female brain phenotype
What does the sry gene encode?
a protein called testis-determining factor (TDF)
XY with a defective Sry gene becomes….
female
An XX mouse inserted with the Sry gene transgenically added to another chromosome becomes…
male
Males with XY have only one copy of a gene so they are?
hemizygous
Females that have two X chromosomes may have?
Heterozygous X chromosome alleles
The gene for Factor VIII is involved in blood clotting cascade is X/Y linked?
X
What is haemophilia A?
a disease where an X-linked recessive trait that is non-functional so no Factor VIII is produced resulting in impaired blood clotting
Canine Muscular Dystrophy in Golden Retrievers is?
an X-linked recessive trait
Lyonisation?
During embryonal development, one of each X chromosomes is randomly inactivated in female cells
so that half of them have an active Xm chromosome and half have an active Xp chromosome
All cells derived from those embryonal cells will have the same X chromosome inactivated forming a mosaic like pattern
What is a Barr body?
the inactive X chromosome in a female somatic cells
What is a gonad?
the primary reproductive organs
Where is the sry gene located?
Y chromosome
