8.3 Controlling cell division Flashcards
What is the purpose of cell cycle checkpoints?
To ensure things are correct before moving to the next stage.
What are the 3 cell cycle checkpoints?
- G1
- G2
- Metaphase (M)
What is the purpose of the checkpoint at the end of G1?
To ensure that:
- There are enough resources to divide
- The cell is big enough
- The DNA is undamaged
What is the purpose of the checkpoint at the end of G2 (similar to G1)?
To ensure that:
- There are enough resources to divide
- The cell is big enough
- The DNA is undamaged
- To check that the chromosomes have been correctly replicated
What is the purpose of the checkpoint at the end of metaphase?
To ensure that:
- The spindle fibres have connected to the sister chromatids and centromeres
- The chromosomes are lined up in the middle
What are the 2 types of cell death?
- Apoptosis
- Necrosis
What is apoptosis (programmed cell death)?
A series of events which result in the dismantling of the internal contents of a cell.
What is apoptosis triggered by?
- Death signals
2. Withdrawal of survival factors
What is necrosis?
The sudden violent death ‘explosion’ of a cell if it is physically damaged or starved of oxygen.
Name the 3 genetic factors of why cancer occurs?
- Proto-oncogenes
- Tumor-suppressor genes
- Inherited genes
What are proto-oncogenes?
Cells involved in controlling the cell cycle that if mutated, continually divides.
What are tumour-suppressor genes?
A group of proteins that tell the cell to slow down cell division, that if mutated, is unable to stop cell division.
What are inherited genes?
Genes that increase the risks of a particular type of cancer.
Name the 3 environmental factors of why cancer occurs?
- Chemicals
- Physical damage
- Biological damage
Give examples of chemicals that can cause cancer:
- Compounds in tobacco
- Some pesticides
- Industrial chemicals
- Asbestos
Give examples of physical damage that can cause cancer:
- X-rays which can cause mutations of DNA
- UV light from the sun or tanning beds can cause skin cancer
Give examples of biological damage that can cause cancer:
-Viruses can cause certain types of leukaemia
What causes neoplasms (tumours)?
Uncontrolled cell division in adults.
Name the 2 main types of neoplasms (tumours):
- Benign
- Potentially malignant
- Malignant
What are benign neoplasms?
Local mass of cells but do not turn into cancer
What are malignant neoplasms?
Masses that migrate to other locations causing cancer and organ disruption.
What can happen if apoptosis fails?
It can result in cancers and autoimmune diseases.
What can happen when there is too much apoptosis?
It can cause a large number of nerve cells to be lost, which may lead to conditions such as Alzheimer disease.
What can happen if the telomeres of a chromosome become too short?
The cell no longer divides or it goes into apoptosis.
