3.8.2.3 Gene Expression and Cancer (C20) Flashcards
Epigenetics has been associated with what type of disease
cancer
All tumours are cancerous - true or false?
false
What is a tumour?
Mass of cell caused by uncontrolled cell division
Cancer is…?
abnormal mass of cells that invades neighbouring tissues or can break away forming secondary tumours
Two types of tumours are?
benign and malignant
Which tumour is cancerous?
malignant
Which tumour does not invade neighbouring cells?
benign
How do cancers spread?
blood stream or via lymphatic system
Name the two genes that control cell division
Proto-oncogenes and tumour suppressor genes
What is the function of a proto-oncogene?
stimulate cell division
what is the function of a tumour suppressor gene?
slow down cell division
what would happen if there was a mutation in a proto-oncogene?
turn into oncogene - uncontrolled cell division
what would happen if there was a mutation in a tumour suppressor gene?
uncontrolled cell division
Mutations in genes that control cell division cause…
cancer
Which type of tumour grows more slowly?
benign
How might tumour cells look compared to normal cells?
different shape
larger/darker nucleus
divide more rapidly
what does methylation do to the DNA?
adds a methyl group to it
In a proto-oncogene what happens to the methylation of the DNA to turn it into a oncogene?
hypomethylation (reduced methylation)
In a tumour suppressor gene what happens to the methylation of the DNA to cause cells to divide out of control?
Increase methylation - turn gene off
Which type of tumour grows rapidly?
malignant
which type of tumour involves using radiotherapy as well as surgery?
malignant
Which type of tumour remains compact
benign
which type of tumour grows finger like projections into surrounding tissue?
malignant
which type of tumour has a capsule?
benign
what are oncogenes?
mutated pro-oncogenes
How to proto-oncogenes stimulate cell growth?
growth factor binds to receptor stimulating cell division
An oncogene can become permanently activated for one of two reasons?
- oncogene codes for a receptor that is permanently activated
- oncogene codes for excessive growth factor
How do tumour suppressor genes work?
they slow down cell division, repair DNA or tell cells to die
what does apoptosis mean?
programmed cell death
Which gene regulates cell division and prevents formation of tumours?
Tumour Suppressor Gene
if a tumour suppressor gene is mutated what is the consequence?
stops inhibiting cell division and cells divide out of control
mutation in a proto-oncogene leads to
oncogenes being activated - uncontrolled cell division
mutation in a tumour suppressor gene leads to
Tumour suppressor gene being inactivated - uncontrolled cell division
abnormal methylation is common in many tumours - what effect can this have on a tumour suppressor gene?
hypermethylation of a tumour suppressor gene - inactivity - uncontrolled cell division (p53 not made)
what is hypermethylation?
addition on methyl groups on DNA - switching off gene expression
transcription of genes is controlled by protein molecules called?
transcription factors
How would methylation of a tumour suppressor gene lead to cancer?
- Methylation prevents transcription of gene;turns off gene expression
- Protein (p53) not produced that prevents cell division/ causes cell death/apoptosis;
- No control of mitosis; uncontrolled cell growth due to mitosis
Describe how alterations to tumour suppressor gene can lead to development of tumours
- increased methylation of tumour suppressor gene
- mutations in tumour suppressor gene
- tumour suppressor gene not expressed
- Leading to rapid uncontrolled cell division
Which cancer gene would be inhibited due to increased methylation?
tumour suppressor gene (TSG) - gene not transcribed!
give one way benign tumours differ from malignant tumours
Cells of benign tumours cannot spread to other parts of the body/metastasise
OR
Cells of benign tumours cannot invade neighbouring tissues;
