Cancer Flashcards
What are acquired mutations?
Mutations that occur in individual cells after fertilisation
What is a tumour?
A mass of abnormal cells
How can acquired mutations cause a tumour?
If they occur in the genes which control the rate of cell division, it can cause uncontrolled cell division
What are cancers?
Tumours that invade and destroy surrounding tissue
What two genes control the rate of cell division?
Tumour suppressor genes
Proto-oncogenes
How does a tumour suppressor gene work?
Slows cell division by producing proteins that stop cells-dividing or cause them to self destruct
What happens if there is an mutation in the tumour suppressor gene?
The gene will stop producing the proteins as the gene will become inactivated. The cells divide uncontrollably
How does a proto-oncogene work?
They stimulate cell division by producing proteins that make cells divide
What happens if there is a mutation in the proto-oncogene?
The gene will become overactive and stimulate cells to divide uncontrollably, resulting in a tumour
What is a oncogene?
A mutated proto-oncogene
What is apoptosis?
Programmed cell death which happens to cells that are infected, damaged or have reached the end of their functions life
What are the two types of tumour?
Benign
Malignant
What are malignant tumours?
Cancers
They grow rapidly and invade and destroy surrounding tissues
What are benign tumours?
Not cancerous
They usually grow slower and are often covered in fibrous tissues that stop cells invading other tissues
What can benign tumours sometimes become?
Malignant
How are tumour cells different to normal cells?
- Their nucleus is larger and darker than normal cells
- They have an irregular shape
- They don’t produce all the proteins needed to function correctly
- They have different antigen on their surface
- They don’t respond to growth regulating processes
- They divide by mitosis more frequently than normal cells
What are two of the causes of tumour growth?
Abnormal methylation
Exposure to oestrogen
What is methylation?
Adding a methyl group to something -CH3
Why is methylation of DNA important?
It can control whether or not a gene is transcribed and translated
What is hypermethylation?
When methylation happens too much
What is hypomethylation?
When methylation happens too little
What happens when tumour suppressor genes are hypermethylated?
Their genes are not transcribed so the proteins they produce to slow cell division aren’t made
What happens when a proto-oncogene is hypomethylated?
Causes them to act as oncogenes
Increases the production of the protein which encourages cell division
Why is exposure to oestrogen thought to increase the chances of breast cancer?
- Stimulate certain breast cells to divide and replicate - more cell divisions increases the chance of mutations occurring
- If cells that replicate do become cancerous, their rapid replication can be further assisted by oestrogen
- Oestrogen is actually able to introduce mutations directly into the DNA of certain breast cells
