Cancer Flashcards
What is Interphase?
Interphase has thee sub phases:
The G1 phase (first gap) centred on growth.
The S phase (synthesis) when the chromosomes are copied.
The G2 phase (Second gap) where the cell completes preparations for cell division.
Then the cell divides. The daughter cells may then repeat the cycle.
Mitosis is broken down into five sub phases, what are they?
Prophase Prometaphase Metaphase Anaphase Telophase
What is a checkpoint in the cell cycle?
Three major ones?
A critical control point where stop and go signals regulate the cycle.
G1, G2, and M phases.
What is the most important checkpoint in the cell cycle and why?
The G1 checkpoint (restriction point). If the cell recieves a go-ahead signal, it usually completes the cell cycle and divides. If it does not receive the signal, the cell exits the cycle and switches to a non dividing state, the G0 phase.
What does the M phase checkpoint in the cell cycle do?
It ensures that all the chromosomes are properly attached to the spindle at the metaphase plate before anaphase.
What external physical factor can influence cell division?
Growth factors.
Proteins released by one group of cells that stimulate other cells to divide.
What is PDGF
Platelet derived growth factor.
Normally in a living organism, platelets release PDGF in the vicinity of an injury. The resulting proliferation of fibroblasts helps heal the wound.
What is density-dependent inhibition of cell division?
Cultured cells normally divide until they form a single layer on the inner surface of the culture container.
If a gap is created, the cells will grow to fill the gap.
At high densities, the amount of growth factors and nutrients is insufficient to allow continued cell growth.
What is anchorage dependence in cell division
Most animal cells exhibit this. To divide they must be anchored to a substratum, typically the extracellular matrix of a tissue.
Control appears to be mediated by connections between the extracellular matrix and plasma membrane proteins and cytoskeletal elements.
How have Cancer cells escaped from cell cycle controls
Cancer cells are free from both density-dependent inhibition and anchorage dependence.
They divide excessively and invade tissues because they are free of the bodes control mechanisms. If and when the cancer cells stop dividing, they do so at random points, not at the normal checkpoints in the cell cycle.
How do cancer cells differ from nearly all mammalian cells during cell division?
Cancer cells may divide indefinitely if they have a continual supply of nutrients. Nearly all mammalian cells divide 20 to 50 times under culture conditions before they stop, age, and die.
Cancer cells may be immortal.
Reactivation of telomerase may play a role
How does the abnormal behaviour of cancer cells begin?
When a single cell in a tissue undergoes nonlethal transformations that convert it from a normal cell to a cancer cell.
If the abnormal cell(s) remain at the originating site, the lump is called a benign tumor.
What is metastasis?
The event where cancer cells lose attachment to nearby cells, are carried by the blood and lymph system to other tissues, and start more tumours.
What does Clonality mean
Originate from a single cell
What does Autonomy & density independent mean?
Growth factors (they either make their own OR the GFR’s are active without GF binding)
What is anaplasia?
Lack of normal coordinated cell differentiation.
Cells are undergoing rapid cell division, so exhibit a high rate of mitosis & have large, dark nuclei.
Develop from mutations that occur along the normal differentiation process.
The earlier the mutation occurs in the differentiation process, the higher the malignancy.
What is a tumour?
Swelling that can be caused by inflammation, infection, trauma, or neoplasia.
What is neoplasm?
A tumour caused by neoplasia.
What is a benign tumour?
Well-differentiated cells clustered together in a single mass; don’t usually cause death unless their size or location interferes with vital functions.
What is a malignant tumour?
Not well-differentiated and has the ability to break loose and enter the circulatory or lymphatic system and form secondary malignant tumours at other sites; usually cause suffering and death if untreated or uncontrolled.
