Cancer

• A gene mutation leads to non-functioning proteins produced which causes non-regulated mitosis.
• Benign tumours are non-cancerous, produce adhesion molecules sticking them together or to a specific tissue and are contained in a capsule so they remain compact and do not spread meaning the impact is localised. Can cause very serious complications still in the brain.
• Malignant tumours are large, cells become unspecialised again, metastasis (tumour breaks off and spreads), can grow projections into surrounding tissues and develop their own blood supply, removal requires supplementary treatment (radiotherapy/chemotherapy) and reoccurrence is more likely.
• Mutation of the gene which creates proteins involved in initiation of DNA replication (proto-oncogene) results in oncogene produced and it is permanently activated causing cells to divide continually.
• Tumour suppressor genes produce proteins to slow down cell division and cause cell death. Mutation of this gene results in no proteins created and continual cell division. BRAC1 and BRAC2 genes cause breast cancer in this way.
• Abnormal methylation (addition of a methyl group) causes tumour suppressor genes to be hypermethylated and permanently turned off. Or cause oncogenes to be hypomethylated (not enough methyl groups) and permanently turned on.
• After the menopause, oestrogen is produced in breast fat tissues. Oestrogen binds to a gen that initiates transcription which activates it. If this is a proto-oncogene then it will continuously activate cell division (permanently activated).