Topic 8A - Mutations And Gene Expression Flashcards
What are the additional 4 mutations?
Addition
Duplication
Inversion
Translocation
What is addition mutation?
One or more bases are added
What is a duplication mutation?
One or more bases are repeated
What is an inversion mutation?
A sequence of bases are inverted and put back into the DNA base sequence (reversed )
What is a translocation mutation?
A sequence of bases are moved from one location to another (can be somewhere on the same chromosome or a different chromosome)
What could a mutation lead to?
Change in the tertiary structure which leads to a change in the function of the protein
What are the 2 genes that control cell division?
Tumour suppressor genes
Proto-oncogenes
What is the function of tumour suppressor genes?
Slow down cell division
What happens if a mutation occurs in the tumour suppressor genes?
Gene will become inactive and the cells will divide uncontrollably resulting in a tumour
What is the function of the proto-oncogene?
Stimulates cell division by producing proteins that make cells divide
What happens if a mutation occurs in the proto-oncogene?
Gene can become overactive, this stimulates cell growth and leads to uncontrollable growth resulting in a tumour
What are the 2 types of tumours?
Malignant
Benign
Describe the characteristics of malignant tumours (3)
Cancerous
Grow rapidly and invade and destroy surrounding tissues
Can spread to other parts of the body
Describe the characteristics of benign tumours? (3)
Not cancerous
Grow slower and often covered in fibrous tissue that stops cells invading other tissues
Often harmless, but can causes blockages and put pressure on organs
Some benign tumours can become malignant
How do tumour cells differ from normal cells? (6)
Have a larger and darker nucleus
Have an irregular shape
Don’t produce all necessary proteins to function proper
Have different antigens on the surface
Don’t respond to growth regulating processes
Divide more frequently than normal cells
State 2 causes of tumour growth?
Abnormal methylation
Increased exposure to oestrogen
How does hypomethylation affect proto-oncogenes?
Increases the production of proteins that encourage cell division
How does hypermethylation affect tumour-suppressor genes?
Can’t be transcribed so the proteins they produce won’t be made
How can cancer be prevented?
If a specific cancer-causing mutation is known, its possible to screen for the mutation
How can cancer be treated?
Gene therapy - where faulty alleles are replaced by working alleles
What are stem cells?
Unspecialised cells which can be differentiated
What are the 4 types of stem cells?
Totipotent
Pluripotent
Multipotent
Unipotent
How’s many types of cells can totipotent stem cells differentiate into?
Any cell
How many types of cells can pluripotent stem cells differentiate into?
Many cells
