Signalling 2 - Signalling in Sex Determination Flashcards
1
Q
What are the gonads?
A
- ovaries
- testes
2
Q
When is the sex of mammals determined?
A
at fertilisation
3
Q
What is the process of sex determination in mammals?
A
- the genetic signal instructing gonad formation
- once the gonads are determined they control the secondary sex characteristics
- Sry is a TF only expressed on the Y chromosome
- Sry will determine the gonads
4
Q
What is Sry?
A
sex determining region Y chromosome (TF)
5
Q
What is the wolffian duct?
A
precursor of vas derferens - male
6
Q
What is the Mullein duct?
A
- precursor of the oviduct - female
7
Q
What is the effect of Sry?
A
- causes gonads to become testes and not ovaries
- male structures persist and female structures disappear
8
Q
How does testosterone signalling work?
A
- hydrophobic steroid hormone
- released into the blood
- crosses the membrane and binds to receptor proteins to regulate gene expression in target cells
9
Q
How do the testes determine secondary sex characteristics?
A
- secrete male hormones which act on distant target cells
- Mullian-inhibiting substance - inhibits the Mullein duct
- testosterone - signals to wolffish dust to develop into vas deferens which will carry sperm
- testosterone - signals secondary male sex character
10
Q
How does female sex determination happen?
A
- no Sry signal
- gonads will become ovaries
- female structures persist
- male structures disappear
- no Mullarian inhibiting substance so oviduct develops
- no testosterone so vas deferans dont develop
- ovaries secrete female hormones which instruct female phenotype
11
Q
What is the default sex?
A
female
12
Q
what are androgens?
A
male characteristic determining hormones
13
Q
what is complete androgen insensitivity syndrome (CAIS)?
A
- some XY people dont have functional receptors fro androgens
- they have internal testes but develop as females
14
Q
What is the gametes of a female chicken?
A
ZW
15
Q
What is the gametes of a male chicken?
A
ZZ
