Cell Cycle Regulation and Cancer Flashcards
Growth Factors
A protein released by certain cells that stimulates other cells to divide
Cyclin-dependent protein Kinases (CDKs)
When a protein kinase is attached to a cyclin, it is a CDK and considered active which gives the “go ahead” signals at the G1 and G2 checkpoints.
GAS PEDAL
Proto-oncogene
A normal cellular gene corresponding to an oncogene; a gene with potential to cause cancer but requires some alteration to become an oncogene.
Codes for a protein that stimulates normal cell growth and division
Oncogene
A gene found in viruses or as part of the normal genome that is involved in triggering cancerous characteristics.
Tumor Suppressor Gene
What is p53 and how does it work?
Tumor suppressor genes inhibit cell division and prevent uncontrolled cell growth.
An active form of p53 codes for a protein that inhibits the cell cycle and prevents damaged DNA from being replicated. It is known as the guardian of the genome. Also, size does not correlate to cancer risk (elephants have more copies of the p53 gene).
What are the 2 Hallmark Characteristics of normal cells?
How is this related to cancer cells?
Anchorage dependence: cells require a surface for a division
Density-dependent inhibition: cells form a single layer
Cancer cells lose these two aspects of normal cells. They divide even though there is a full layer and don’t require a surface for division.
A drug that blocks cohesin degradation would have what effect during mitosis?
Sister chromatids would fail to separate during anaphase.
What are checkpoints?
What is needed for the G1/S checkpoint?
Checkpoints are critical control points where stop and go signals regulate the cycle.
At the G1 checkpoint, CDK4/6 and Cyclin D signaling is key. Genes necessary for DNA replication are expressed.
What happens if the cell does not receive the go ahead signal at the G1 checkpoint?
The cell goes into a ‘resting state’ known as G0.
What are MPFs
MPFs are a kind of CDK that promotes mitosis. It is needed to pass the G2 checkpoint.
Mitosis Promoting Factor?
Maturation Promoting Factor
What is the stop signal in prometaphase and the go signal in metaphase?
In prometaphase, a stop signal is sent when any chromosomes are not attached.
In metaphase, a go signal is sent when all chromosomes are attached.
This is in relation to the M checkpoint.
What is the effect of platelet-derived growth factor on Cell Division?
PDGF’s promote cell proliferation. It is required for the division of culture fibroblasts.
GAS PEDAL
Explain the process of the metastasis of a malignant breast tumor.
- A tumor grows from a single cancer cell
- Cancer cells invade neighbouring tissue
- Cancer cells spread through lymph and blood vessels to other parts of the body
- A small percentage of cancer cells may metastasize to another part of the body.
These cancer cells have lost anchorage dependence.
What mutations can convert a proto-oncogene into an oncogene?
- Point mutation: produces a hyperactive or degradation-resistant protein
- Gene amplification: multiple copies of the gene exist
- Translocation: gene moved to new locus
How does the ras gene work as a proto-oncogene and what converts it into an oncogene?
The ras gene normally codes for a protein that stimulates the cell cycle. However, a point mutation causes a hyperactive ras protein to issue signals without the need for a growth factor, increasing cell division through overexpression.
