Cancer Flashcards
(10 cards)
Name characteristics of benign tumours
- not cancerous
- grow slower than malignant
- covered in fibrous tissue which prevents cells invading neighbouring cells
- can cause blockages and put pressure on other organs
Name the characteristics of malignant tumours
- cancerous, usually invade and destroy surrounding tissue
- nucleus appears darker as more DNA content
- cells can break off from the tumour and spread to other parts of the body through the blood or lymphatic system
Which types of gene control the rate of cell division.
Proto-oncogenes and tumour suppressor genes
Acquired mutations in these genes can cause uncontrolled cell division, forming a tumour
How do tumour suppressor genes control the rate of cell division?
Maintains normal rate by producing proteins which stop cell division or cause apoptosis- programmed cell death
If mutation occurs in these genes it is inactivated so protein cannot be produced so cells that are undergoing mitosis at abnormally fast rate with continue to divide uncontrollably
How do proto-oncogenes control the rate of cell division?
Stimulates cells to divide when growth factors attach to a protein receptor on the cell surface membrane
- this activates genes which cause DNA to replicate
If mutated it can become an oncogene which is permanently switched on, receptor on cell surface is permanently activated despite the presence of growth factors or not.
How do tumour cells differ from normal cells?
- larger darker nucleus, sometimes multiple nuclei
- have different antigens on its cell surface and an irregular shape
- don’t produce all the proteins required to function properly
- don’t respond to growth regulating processes
How does abnormal DNA methylation affect tumour suppressor genes? + name an example
Hyper methylation occurs at the promoter region of a tumour suppressor gene.
- transcription of promoters inhibited
- leads to the gene being inactivated, cannot be transcribed, increased rate of cell division
E.g occurs in BRACA1 gene which leads to development of breast cancer
How does abnormal DNA methylation affect proto-oncogenes?
Hypo methylation of proto oncogenes leads to them becoming oncogenes, permanently activated so rate of cell division increases and tumour forms.
How does increased oestrogen concentrations lead to development of some breast cancers?
After menopause increased breast cancer risk due to increased oestrogen concentrations
Exact reasons aren’t fully understood however theories include:
- oestrogen can stimulate certain cells to divide and replicate, increased cell division= increased chance of mutations
- also if cells become cancerous oestrogen assists in rapid replication
How is breast cancer treated/ prevented?
It is possible to screen for specific cancer causing mutation in a patients DNA
Treatment is different for different mutations and can include gene therapy or radiotherapy
