Fertilisation III (2nd lecture) Flashcards
(32 cards)
When during meiosis are the oocytes arrested?
Second metaphase
When do oocytes complete meiosis?
After fertilisation
What do chromosomes look like at metaphase II?
an X (2c, 1n)
What does the spindle do to the two halves of the x shape after fertilisation?
Pulls them apart
What happens between metaphase II and anaphase II?
Production of a second polar body
What genetic complement does the polar body contian?
1c=1n
What happens to the polar body after it is formed?
Plays no further part in development
Where do the maternal chromosomes come from?
The other half o the chromosomes that the polar body ones came from
What does Emi2 stand for?
endogenous meiotic inhibitor 2
What is Emi2?
the principal cytostatic factor in many organisms
What is a cytostatic factor?
One that inhibits cell division
In which organisms if Emi2 the primary cytostatic factor?
Xenopus, mouse, human,
When does Emi2 arrest the oocyte?
Meiosis II until fertilisation
What does Emi2 stabilise?
Maturation promoting factor (MPF
What is MPF mde up of?
heterodimer of Cdc2 (=Cdk1) and Cyclin B
What is Cdc2?
a cyclin-dependent kinase (Cyclin B)
What are some MFP kinase targets?
Myosin, condensins, separase, H1, H3
What is myosin needed for in meoisis?
Cytokinesis
Role of condensins?
Promote chromosome condensation
Rome of separases?
Chromosome separation
What does MPF stabilisation cause?
mII and mitotic M-phase arrest
What is metaphase arrest by Emi2 is unique to?
Meiosis
What happens to the nuclear membrane in the Emi2 arrested cell?
It isnt present around the chromosomes
What is Emi2 also present in?
Mitosis
