Cancer Flashcards
What is an acquired mutation?
A mutation that occurs in individual cells after fertilisation
When can uncontrolled cell division occur?
If an acquired mutation occurs in the genes that control the rate of cell division
What can form if a cell divides uncontrollably?
A tumour
What is a tumour?
A mass of abnormal cells
What is cancer?
Tumours that invade and destroy surrounding tissue
Name the 2 genes that control cell division
Tumour suppressor genes
Proto -oncogenes
Explain what happens if tumour suppressor genes become mutated
They become inactive if a mutation occurs in the DNA sequence. If a mutation occurs in the tumour suppressor genes the protein isn’t produced. This means that cells divide uncontrollably resulting in a tumour.
Explain what happens when a tumour suppressor gene is functioning normally
Tumour suppressor genes slow cell division by producing proteins that stop cells dividing or causing them to self destruct
What is apoptosis?
When cells self destruct
Explain what happens if proto-oncogenes become mutated
The effect of proto-oncogenes can be increased if a mutation occurs in the DNA sequence. The gene can become overactive which stimulates the cells to divide uncontrollably resulting in a tumour.
Explain what happens when a proto-oncogene is functioning normally
Proto-oncogenes stimulate cell division by producing proteins that makes cell divides
What is a mutated proto-oncogene called?
Oncogene
Describe a malignant tumour
- grow rapidly
- cancerous
- invade and destroy surrounding tissues
- cells can break of the tumour and spread to other parts of the body in the bloodstream or lymphatic system
Describe a benign tumour
- grow slowly
- covered in fibrous tissue that stops cells invading other tissue
- not cancerous
- often harmless but can cause blockages and put pressure on organs
- some benign tumour can become malignant
Describe features of tumour cells
- have an irregular shape
- large and dark nucleus
- sometimes have more than one nucleus
- do not produce all the proteins needed to function properly
- have different antigens on their surface
- do not respond to growth regulating processes
- they divide frequently
What is methylation?
The process of adding a methyl group onto something
Why is methylation of DNA an important method of regulating gene expression?
It can control whether or not a gene is transcribed and translated
When does methylation become a problem?
When it happens to much or too little
What is hypermethylation?
When methylation happens too much
What is hypomethylation?
When methylation happens too little
What can be causes as a result of abnormal methylation?
Growth of tumours
Explain what happens when tumour suppressor genes are hypermethylated
The genes are not transcribed.
The proteins they produce to slow down cell division are not made. This means that cells are able to divide uncontrollably by mitosis and tumours can develop
Explain what happens when proto-oncogenes are hyopmethylated
Makes them act as oncogenes.
This increases the production of the proteins which encourages cell division which encourages cell division. This stimulates cells to divide uncontrollably which causes the formation of tumours
What can increase a woman’s risk of developing breast cancer?
Increased exposure to oestrogen over an extended period of time
Why can exposure to oestrogen result in the development of breast cancer?
Oestrogen can stimulate certain breast cells to divide and replicate. The fact that more cell divisions are taking place naturally increases the chance of mutations from occurring and so increases the chance of cells becoming cancerous.
Name the two types of risk factors for cancer
Genetic
Environmental
What are genetic risk factors?
Some cancers are linked with specific inherited alleles. If you inherit that allele you are more likely to get that type of cancer.
What are environmental risk factors?
Exposure to radiation
Lifestyle choices
Increased alcohol consumption
High fat diet
What are the 4 ways of treating cancers?
Surgery
Immunotherapy
Chemotherapy
Radiotherapy
What does surgery do?
Removes a specific tumour if it hasn’t spread.
This can, however, lead to breakages and spreading of cells of not done carefully
What does immunotherapy do?
Help direct treatments to cancerous cells to reduce side effects and damage to the body
What does chemotherapy do?
Prevents the synthesis of the enzymes required for DNA replication. This stops the cell cycle before the S phase as it cannot take place. If DNA cannot be replicated cells won’t be able to divide
What does radiotherapy do?
Damages DNA and forces the cell to kill itself
