R&G Quiz 1 - Sex Determination

What chromosome is associated with males

Y chromosome

The absence of what chromosome is associated with females

X chromosome

Primary sex determination

gonads develop into testes or ovaries

secondary sex determination

male/female phenotypic differences by hormones

sexually dimorphic traits

differences you can see between males and females (eg Lions mane)

At what time in the pregnancy are the gonads/ducts forming

4-7 weeks

What chromosome directs testes formation

Y chromosome

What directs ovary formation

absence of Y chromosome

Is wolfian duct male or female

male

is mullerian duct male or female

female

What do the testes produce

Testosterone and AMH

What does AMH do

destruction of mullerian duct

When will the mullerian duct form

absence of testosterone/AMH

prevents wolfian formation

What gene is required for the formation of testes

SRY gene on the Y chromosome

What phenotype will a XXY person have

male

Turner’s syndrome

45, X

develop as sterile females

Klinefelter’s syndrome

47, XXY

develop as males with low fertility

Androgen Insensitivity

mutation in X-linked androgen receptor, causing XY males to become phenotypically female

• testosterone is produced, but no receptors

• develop as infertile females - no ovaries/uterus/Mullerian duct

Where is the androgen receptor gene

On X chromosome (X-linked disorder)

What forms a Barr Body

An inactivated X chromosome

Why is the test flawed

Males and X0 individuals do not produce barr bodies

Barr bodies cannot always be found during the test