Topic 8A: Cancers Flashcards
How does cancers occur?
When mutation in genes cause an uncontrollable cell growth. This eventually forms tumours
What are acquired mutations?
Mutations that occur in the individual cells after fertilisation
What causes uncontrolled cell divisions?
When the mutations occur in the genes that control the rate of cell division
What are tumours?
-a mass of abnormal cells
How do you know the tumours are cancerous?
they invade and destroy surrounding tissues
Name the types of genes that control cell division
- tumour suppressor genes
- proto-oncogenes
What do tumour suppressor genes do when they function normally?
- they slow cell division by
- producing proteins that stop cells dividing
- or cause them to self destruct (apoptosis)
What happens if the tumour suppressor genes are mutated in the DNA sequence?
- the genes get inactivated
- the protein to stop cells dividing isn’t produced
- therefore cells divide uncontrollably
- rate of cell division increases
- results in a tumour
What do proto-oncogenes genes do when they function normally?
- the genes stimulate cell division
- by producing proteins that make cells divide
What happens if the proto-oncogenes genes are mutated in the DNA sequence?
- the effect of proto oncogenes are increased
- gene becomes overeactive
- stimulates cells to divide uncontrollably
- rate of cell division increases
- results in a tumour
What do you call a mutated proto oncogene?
oncogene
What are the two types of tumours?
Benign
Malignant
What are benign tumours?
- non cancerous tumours
- grow slower than malignant tumours
- often covered in fibrous tissue which stops cells invading other tissues
- can cause blockage and put pressure on organs
Can benign tumours turn into malignant?
Yes
What are malignant tumours?
- cancerous tumours
- grow rapidly
- invade and destroy surrounding tissues
- cells can break off the tumours and spread to other parts
- like bloodstream/lymphatic system
How do tumour cells looks different to normal cells?
- irregular shape
- nucleus larger and darker
- sometimes more than one nucleus
- dont produce all the proteins needed
- different antigens on their surface
- they don’t respond to growth regulating processes
- divide more frequently
What is methylation?
adding a methyl group on something
Why is the methylation of DNA important?
Because it ca control whether or not a gene is transcribed (copied into mRNA) and translated (turned into protein)
Abnormal methylation caused by
growht of tumours
Tumour suppressor genes are….
HypERmethylated
Proto oncogenes are
HypOmethylated
What does hypermethylated tumour suppressor gene leads to?
- genes not transcribed
- proteins to slow cell division is not made
- cells divide uncontrollably by mitosis
What does hypormethylated proto oncogene gene leads to?
- act as oncogenes
- increases production of proteins for cells to divide
Increased exposure to oestrogen can….
increase a woman’s risk of developing breast cancer
What causes the increase exposure to oestrogen?
- starting menstruation early than usual
- starting menopause later than usual
- result in taking oestrogen containing drugs such as HRT
Outline theories on how oestrogen contribute to the development of some breast cancer…
1) -oestrogen can stimulate certain breast cells to divide and replicate
- the more cell divisions can increase the chance of cells becoming cancerous
2) oestrogen maybe actually able to introduce mutations directly into the DNA of certain breast cells.
- increase the chance of these cells becoming cancerous
