Unit 1: Control of the Cell Cycle Flashcards
The control of the cell cycle can be studied using model organisms such as?
Yeast
When does the G1 checkpoint take place?
At the end of G1 before S phase
When does the G2 checkpoint take place?
At the end of G2 before the start of the M-phase
When does the M checkpoint take place?
Before the beginning of anaphase
What is checked for at the G1 checkpoint?
Cell size and environmental conditions
What is checked for at the G2 checkpoint?
Correct replication of DNA
What is checked for at the M checkpoint?
Chromosomes correct attachment to spindle fibres
Cells need an adequate nutrient supply to proliferate, plus what else?
Serum
Serum needed for cell proliferation contains a protein causes what to happen?
It stimulates the cells to continue through the cell cycle
Extracellular signal molecules with the ability to stimulate the cell to continue the cell cycle are called?
Mitogens
Mitogens are?
Extracellular signal molecules with the ability to stimulate the cell to continue the cell cycle
In the absence of Mitogens what happens to the cell cycle?
Cells in the cycle enter the G0 phase
What happens in the G0 phase of the cell cycle?
Cells don’t divide
For how long do the cells remain in the G0 phase of the cell cycle?
They can remain here forever or re-enter the cell cycle when appropriate.
Give two examples of cells than can proliferate continuously
Stem cells and Tumour cells
Liver cells exist constantly in the G0 phase until?
The liver becomes damages and new cells are needed
Give the three type of cells that exist in terminally differentiated states?
Red blood cells, Neurons and Skeletal Muscle
The cell cycle is controlled by the activity of what?
Cyclin dependent kinases (Cdk)
The cell cycle control system can be studied using model organisms such as
Spisula
High release levels of cyclin proteins indicate what process is taking place?
Mitosis
The activity of Cdks is regulated by
cyclins
Different cyclins bind to Cdks when?
At different phases of the cell cycle
A cyclin binds to G1 Cdk to allow…
cell passage through G1 checkpoint
A cyclin binds to S Cdk to allow…
a cell to initiate DNA replication
A cyclin binds to M Cdk to promote…
Mitosis
A certain level of phosphorylation of what cells, results in the cell progressing to the next stage of the cycle?
Target proteins
Active Retinoblastoma protein (Rb) does what?
Inhibits cell cycle progression
Retinoblastoma is target by what?
G1-Cdk
Once the G1-Cdk works on the retinoblastoma two what are added causing the retinoblastoma to go from active to active?
Phosphates
P53: Stage 1, Mutagen damages DNA triggering what?
Protein kinase activity
P53: Stage 2, Protein kinase activity causes what to happen to p53?
It goes form unstable to stable by addition of a phosphate
P53: Stage 3, Activated P53 induced what?
Transcription of genes that cause cell cycle arrest
P53: Stage 4, Cell cycle arrest gene ______ is expressed?
p21
P53: Stage 5, Production of p21 causes the cyclin-cdk complex to become?
inactivated
What are the top three things Activated p53 does?
Stimulates DNA repair, promotes transcription of cell cycle arresting genes and genes that induce apoptosis
What is the name of a genetic disease associated with the inability to activate p53?
Ataxia telangiectasia
