The Embryo: Cell Cycle I Flashcards
How is the cell cycle stimulated?
By Cyclin-dependent kinases (cdk)
How are cdk’s are regulated?
Through cyclins
Which cdk’s control what?
Which cyclins control what?
Order: G1, S, G2, M Cdk: "6,4,2,1" 4,6 - G1 2 - G1/S, S, G2 1 - G2/M, M
Cyclins: "DEAB" D - G1 E - G1/S A - S, G2 B - G2/M, M
What occurs during G1 Phase
Allows daughter cells to grow after cytokinesis
Restriction point for entering into S phase based on conditions
How is G1 phase regulated?
Inhibited by phosphorylation at active site
Inhibited/Phosphorylated by Wee1
Dephosphorylated by cdc25
What drives G1 into next phase?
Activated cdks (6 or 4) will phosphorylate pRB (retinoblastoma protein)
Importance of Mitogen Receptor pathway?
and pathway
Once activated, produces Myc proteins that are responsible for activating cdk’s (6 and 4) for G1 to begin
Mitogen binds to receptor > activates MAP Kinase > signal reaches nucleus > activates transcription factors for activating of Myc Gene
Importance and characteristics of pRB?
Major tumor suppressor
When hypo-phosphorylated (un) pRB binds to E2F transcription factors
Phosphorylated (activated) by cdk4/cyclin D and cdk6/cyclin D, & cdk2/cyclin E complexes.
What occurs during S phase?
DNA synthesis
What occurs during G2 phase?
Build up of cell contents
Chromatin organization for mitosis
What occurs during M phase?
M: Mitosis (PProMMAT C)
Nuclear envelop breaks down, chromosome condensation, cell division
Prophase, prometaphase, metaphase, anaphase, telophase, cytokinesis
Summary of M phase?
Mitosis occurs
Chromosome condensation & alignment at equatorial plane
Nuclear Division
Chromosome speration, decondensation, nuclear membrane reformation
Cell division [cytokinesis]
Division into two daughter cells, 23 pairs of chromosomes per cell
