Gene Expression- Cancer Flashcards
What are acquired mutations?
Mutations that occur in individual cells after fertilisation
How can uncontrolled cell division be caused?
If these mutations occur in the genes that control the rate of cell division
What is a tumour?
A mass of abnormal cells
What are cancers?
Tumours that invade and destroy surrounding tissue
What are the two types of genes that control cell division?
Tumour suppressor genes and proto-oncogenes
What can mutations in tumour suppressor genes and proto-oncogenes cause?
Cancer
Why are tumour suppressor genes inactivated?
If a mutation occurs in the DNA sequence
What do tumour suppressor genes do when functioning normally?
Slow cell division by producing proteins that stop cells dividing or cause them to self-destruct (apoptosis)
What happens if a mutation occurs in a tumour suppressor gene?
The protein isn’t produced and the cells divide uncontrollably (the rate of division increases) resulting in a tumour
How can the effect of a proto-oncogene be increased?
If a mutation occurs in the DNA sequence
What is an oncogene?
A mutated proto-oncogene
What do proto-oncogenes do when functioning normally?
Stimulate cell division by producing proteins that make cells divide
What happens when a mutation occurs in a proto-oncogene?
The gene becomes overactive which stimulates cells to divide uncontrollably (rate of division increases) resulting in a tumour
What are the two different types of tumour?
Malignant and benign
What are malignant tumours?
Cancers that usually grow rapidly and invade and destroy surrounding tissues- cells can break off the tumours and spread to other parts of the body in the bloodstream or lymphatic system
What are benign tumours?
Not cancerous that usually grow slower than malignant tumours and are often covered in fibrous tissue that stops cells invading other tissues- often harmless but can cause blockages and put pressure on organs, can become malignant
What are the 6 ways tumour cells can differ from normal cells?
- Irregular shape
- Nucleus is larger and darker or may have more than one nucleus
- Don’t produce all the proteins needed to function correctly
- Have different antigens on surface
- Don’t respond to growth regulating processes
- Divide more frequently
What does methylation work?
Adding a methyl group onto something
How 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 too much (hypERmethylation) or too little (hypOmethylation)
What can abnormal methylation of certain cancer-related genes cause?
The growth of tumours
What does hypERmethylation of tumour suppressor genes cause?
Genes not being transcribed so the proteins they produce to slow cell division aren’t made- means the cells are able to divide uncontrollably by mitosis and tumours can develop
What does hypOmethylation of proto-oncogenes cause?
Them to act as oncogenes to increase the production of proteins that encourage cell division- stimulates cells to divide uncontrollably to cause the formation of tumours
What is increased exposure to oestrogen thought to cause?
Increase a woman’s risk of developing breast cancer
What are the 3 reasons that oestrogen may contribute to development of breast cancer?
- Oestrogen can stimulate certain breast cells to divide and replicate- more cell divisions are taking place naturally increases chance of mutations occurring so increases chance of cells becoming cancerous
- Ability to stimulate division could also mean that if cells do become cancerous, rapid replication could be further assisted by oestrogen to help tumours form quickly
- Research suggests that oestrogen is actually able to introduce mutations directly into DNA of certain breast cells which again increases risk of cells becoming cancerous
