Zygotic gene activation Flashcards
(31 cards)
What are the amounts of cells in the first mitotic cell cycles after fertilisation?
1c->2c->4c->8c->16c
What happens at the 16 c stage in mammals?
Compaction
What happens to the overall volume of the embryo over the first cell division after fertilisation?
Little change, maybe a v slight increase
How large are the daughter cells compared to their respective mothers in the first few cell divisions?
~half the size
What is required for the first few cell divisions?
Maternal factors
Where do maternal factors come from?
inherited from the egg (oocyte), eg protein and mRNA
When does addition of cytoplasm usually occur in the cell cycle?
G1
WHat stage of the cell cycle is short in embryonic cleavage?
G1
Outcome of G1 stage being short in embryonic cleavage?
Little addition of new cytoplasm
Why do blastomeres have an asymmetric fate?
They produce germ cells
What is genesis of multicellularity an early feature of?
Embryonic development
What is an embryo cell called?
A blastomere
Names for cell division?
cytokinesis (nuclear division, karyokinesis)
What is the yolk for?
A source of nutrients for the early emb ryo
What is the cleavage furrow?
An actomyosin ring that divides cells
Which pole is the yolk closest to?
Vegetal pole
What is actomyosin made up of?
myosin and F-actin microfilament
Is actomyosin-independent cytokinesis possible?
SOme evidence to support it
How is the cleavage plane related to the spindle?
It equatorially bisects whichever orientation the spindle is in
Which plane are the first two divisions in?
Same plane
What shape do the first two divisions make (birds eye view?
x or +
What plane is the third division in?
Opposite plane to the first two–> cuts each of the 4 cells in half
What causes the cleavage furrow?
F actin and myosin
What does the cleavage furrow define?
The division plane of the cell
