Mitosis & Cancer
Biology: Cambridge International A Level, topic 5.1.6
Cancer
Cancer comprises many different diseases caused by a common mechanism: uncontrolled cell growth.
Gene mutations
- Although the cell cycle is tightly controlled by genes, errors do happen.
- Changes to the DNA nucleotide sequence can cause a gene mutation.
- A gene mutation may give rise to a faulty protein.
- The change in the cell that results from the malformed protein may allow subsequent mistakes to happen more often.
Uncontrolled cell division
- Small uncorrected errors are passed from the parent cell to the daughter cells.
- As each generation produces more non-functional proteins from uncorrected DNA damage, mutations accumulate.
- This can lead to uncontrolled growth of the mutated cells. This creates a tumour.
Treatment of Cancer
Cancer is caused when the cell cycle is not properly controlled. Cancer can be treated by targeting the phases of the cell cycle.
G1
- G1 is a phase in interphase that produces new organelles and causes the cells to grow in size.
- If the genes that encode the enzymes involved in this process are mutated, the cell cycle can be altered.
- Drugs can be targeted to inhibit G1 and treat cancerous cells.
- The drugs halt the cell cycle and kill the cells.
S phase
- S phase is the stage in interphase that causes DNA to replicate.
- Errors in DNA replication can lead to the development of tumours.
- Drugs can be targeted to damage the DNA and kill the cells to prevent the spread of a tumour.
Test yourself on Mitosis & Cancer
What is the common mechanism that causes cancer?
Which of the following statements about cancer are true?
Which of the following statements about treating cancer are true?
What phase of the cell cyle are the G1 and S phase found in?