Module 8 - Cancer Flashcards
What are mutations that occur after fertilisation called?
Acquired mutations
How does cancer occur?
A mutation in a gene that controls the rate of cell division. If this causes uncontrollable cell division, this can result in a tumour which could be cancerous if it invades and destroys surrounding tissue
What are the two types of genes that control cell division?
Tumour suppressor genes and proto-oncogenes
How do tumour suppressor genes work when functioning normally?
When functioning normally, tumour suppressor genes sow cell division by producing proteins that stop cells dividing or cause them to self destruct
How can a mutation in the tumour suppressor genes lead to cancer?
If a mutation occurs in a tumour suppressor gene, the protein may not be produced. The cells will then divide uncontrollably resulting in a tumour
How does a proto-oncogene work when functioning normally?
Proto-oncogenes stimulate cell division by producing proteins that that makes cells divide
How does a mutation in the proto-oncogenes cause cancer?
If a mutation occurs, the gene can become overactive. This stimulates the cells to divide uncontrollably resulting in a tumour
What are the two types of tumours?
Malignant and benign
What are malignant tumours?
They usually grow rapidly and invade and destroy surrounding tissue. These cells can break off from the tumours and spread to other parts of the body in the bloodstream or lymphatic system - cancerous
What are benign tumours?
These grow sower and are covered in fibrous tissue that stops the cells invading other tissue. They are non-cancerous but they can cause blockages and pressure on organs
How do tumour cells differ to normal cells?
- They have an irregular shape
- The nucleus is larger and darker
They don’t produce all the proteins needed to function correctly - They have different antigens on their surface
- divide much more frequently
What is methylation?
Adding a methyl group onto something and determines whether or not a gene is transcribed or translated
What is the difference between hypermethylation and hypomethylation?
Hypermethylation - too much methylation
Hypomethylation - too little methylation
What genes are hypermethylated?
Tumour suppressor genes
How does hypermethylation lead to tumour growth?
When the tumour suppressor genes are hypermethylated, they genes are not transcribed so the proteins to slow cell division aren’t being made. This causes cells to divide uncontrollably and cause tumours to develop
How does hypomethylation lead to the growth of tumours?
Hypomethylation of proto-oncogenes causes them to act as a oncogene - increasing the production of the proteins that encourage cell division. This stimulates cells to divide uncontrollably, causing the formation of tumours
Explain how an increase in oestrogen can contribute to some breast cancers?
1) Oestrogen can stimulate some breast cells to divide and replicate, This increase in cell division increases the chances of mutations occuring, this means there is a higher chance of cells dividing more rapidly leading to tumours. If cells do become cancerous, the rapid replication could be further assisted by oestrogen, helping tumours form quickly.
How are some drugs effective treatment of ER-positive breast cancers?
- The drugs will bind to oestrogen receptors
- This prevents the binding of oestrogen to the DNA binding site
- Prevents the transcription factors binding to promoters reducing uncontrolled cell division
