Cancer
- Created by: polly
- Created on: 02-02-13 15:44
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- Cancer
- What is it?
- cells divide rapidly forming a mass of abnormally growing cells
- tumour
- may split, releasing clumps into the blood and lymph systems
- can form secondary tumours when they lodge somewhere and continue rapid growth
- malignant tumour
- metastasis
- can form secondary tumours when they lodge somewhere and continue rapid growth
- may split, releasing clumps into the blood and lymph systems
- invades surrounding cells
- tumour
- live longer than normal cells
- cells divide rapidly forming a mass of abnormally growing cells
- Mutations that cause it
- 15% of human cancers are due to viral infections
- human papillomavirus is responsible for almost all cervical cancer cases
- the mutations that cause cancer affect the control of the cell cycle
- usually by disrupting chemical systems
- multiple mutations result in a cancerous cell
- hence why risk of cancer increases as age increases
- this can often lead to:
- inaccurate replication of DNA
- decreased efficiency of DNA repair
- increase in likelihood of chromosomesbreaking & rearranging
- however, some cancers are the result of a single gene mutation
- proto-oncogenes
- code for proteins that stimulate cell cycle
- 1 gene mutates = oncogene
- oncogene produces uncontrolled amounts of the proteins
- so cell cycle is continuous = cancer
- oncogene produces uncontrolled amounts of the proteins
- 1 gene mutates = oncogene
- code for proteins that stimulate cell cycle
- tumour suppressor genes
- normally produce chemicals suppressing cell cycle
- mutation = cycle cycle continuous = cancer
- normally produce chemicals suppressing cell cycle
- proto-oncogenes
- 15% of human cancers are due to viral infections
- Role of environment
- tar in cigarette smoke
- chemicals in alcoholic drinks
- asbestos
- ionising radiation
- UV radiation in sunlight
- malignant melanoma
- cancer of cells that produce the pigment melanin
- particularly damaging if sunburnt during childhood
- melanin acts as a natural sunscreen
- sunscreens either absorbs UV or reflect it
- cancer of cells that produce the pigment melanin
- malignant melanoma
- What is it?
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