Lecture 2 - Generation of embryo cells Flashcards
What is cleavage of the embryo?
- Splitting of the single cell into 100’s of cells
- Cells reduce in size
What are the six type of cleavage patterns? [6]
- Radial
- Discoidal
- Bilateral
- Superficial
- Spiral
- Left/Right-handed coiling
How is the direction of coiling determined?
By the maternal genotype
How is cleavage different between mammals and other animals? [5]
- Divisions are slower
- Divisions are not synchronous
- Plane of cleavage can differ
- Not dependent on mRNAs and proteins in the egg
- Undergo compaction
What happens to cell division after cleavage?
It is no longer synchronous
What is needed for the division in Drosophila after the cleavage stage?
Zygotic expression of String protein
What does string code for?
Cdc25
What does Cdc25 regulate?
CDK1/cdc25 activity
What two enzymes phosphorylate CDK1?
- Wee1
- CDK1 activating kinase
What does Cdc25 do to the double phosphorylated CDK1?
- Removes the inhibitory phosphate from Tyr-15
- Activated CDK1
What does activated CDK1 do?
Phosphorlyates a wide range of proteins to cause mitosis
Which cycle does expression of string start?
Cycle 14 in normal embryos
What is the cell cycle like during cleavage?
> Mitosis
DNA synthesis
Repeat
What is the cell cycle like after cleavage?
> Mitosis > G1 > DNA synthesis > G2 > Repeat
