LOOs 12 Flashcards
What is the most basic function of the cell cycle?
to duplicate DNA and generate two genetically identical daughter cells
In general, how long does this take in mammalian cells and what is a reasonable reason as to why it takes so long?
S phase, 10-12 hrs
M phase >60 mins
There is alot of DNA to be replicated in S phase
What are the four stages of the cell cycle?
G1 -> S -> G2 -> M
G1 and G2 are the gap phases that allow time for cell to grow and make sure everything is okay before moving on to next phase
S is DNA replication
M is the morphologically changes the cells undergoes when seperating
How are the four stages of the cell cycle ‘grouped’?
G1, S, G2 - make up interphase
M - makes up mitosis (prophase, prometaphase, metaphase, anaphase, telophase) and cytokinesis
What is G0 and how variable can it be?
- also known as the resting phase, is the period of the cell cycle during which the cell is neither dividing nor preparing to divide
- can be days, months, years, or until cell death
What are two experimental techniques we can use to monitor/follow progression through the cell cycle?
1) Fluorescence Microscopy
- timing of cell cycle phases can be measured using fluorescently labeled proteins that appear and disappear
2) Flow Cytometer using Fluorescence Activated Cell Sorter (FACS)
-measure DNA content by staining cells w dye that becomes fluorescent when DNA binds
What is the cell-cycle control system? How does it generally function?
controlled by biochemical switches have binary on/off switches that are irreversible.
3 key transitions
-Start, is environment favorable -> cell cycle commitment
-G2/M, is environment favorable and is all DNA replicated -> mitosis
-Metaphase to anaphase, are all chromosomes attached to spindle -> cytokinesis
What are cyclin-dependent kinases (Cdk)?
-the binary switch of the cell cycle, if kinase is on switch is one and vice versa.
-Cdk does not change concentration throughout the cell cycle
What are cyclins?
-the substrate to the enzyme kinase that slightly activates it need activating phosphate to fully activate it.
-cyclins do change concentration as cell cycle progresses it is constantly degraded and synthesized. Different cyclins stimulate different events
How are both Cdks and cyclins regulated?
-CAK (Cdk-activating kinase) add the activating phosphate , activating complex
-Wee 1 kinase adds inhibitory phosphate to cyclin-Cdk complex, inactivating it
-Cdc25 removes inhibitory phosphate making cyclin-Cdk complex active
-CKIs (Cdk inhibitor proteins) bind to cycllin-Cdk complex and allosterically inhibits it
What is PP2A?
protein phosphatase 2A removes the activating phosphate added by Cdk
How do different B subunits affect PP2A function?
regulated by greatwall kinase sends a phosphorylated ensa that binds and inhibits PP2A
Be able to understand, explain, and interpret the G2/M phase transition, alterations to this pathway, and how it is regulated.
look at notes
What is APC/C? How does it contribute to the cell cycle? What are its targets?
Anaphase-promoting Complex/Cyclosome triggers metaphase to anaphase transition by destroying S and M-cyclins which inactivates most Cdk in cell allowing PP2A to dephosphorylate proteins phosphorylated by Cdk marking the end of M phase
How is it regulated APC/C?
sequential activation
1) Cdc20 - trigger the destruction of securin and cyclins, resulting in chromosome segregation in anaphase
2) Cdh1 - ensures that cyclins and other proteins are kept at low levels until the following cell cycle.
