14.1-14.2 Cancer is a genetic disease Flashcards
What is cancer?
When cells have lost the normal control of cell division and cell growth becomes unregulated
Which are the most commonly diagnosed cancers in the world?
- Lung
- Breast
- Colorectal
- Stomach
- Prostate
Where in the world are cancer deaths more likely to occur?
Less developed countries
What is cancer caused by?
Mutations in DNA that alter the way a gene functions and allow a cell to grow, multiply and spread in an abnormal way
What is a somatic mutation?
Somatic mutations affect a particular tissue and are heritable.
What are susceptibility genes?
Some people are born with genes that give them an increased susceptibility to cancer
Where do most mutations arise from?
Environment and lifestyle
How many genes are in the human genome and how many are known to contribute to the progression of cancer?
Between 20,000 to 25,000 genes in genome
Over 400 know to contribute to cancer
Broadly, how many types of cancer genes are there?
4
What is an oncogene?
A gene that has the potential to cause cancer
What are proto-oncogenes in normal cells?
Genes that help promote cell growth. Apart from when a cells needs to grow and divide, these genes are normally switched off and are not active
What happens to proto-oncogenes in cancer cells?
Changes or mutations in a proto-oncogene can switch the gene on, causing it to become an oncogene, which signals the cell to grow and divide into a tumour
What happens to proto-oncogenes in cancer cells?
Changes or mutations in a proto-oncogene can switch the gene on, causing it to become an oncogene, which signals the cell to grow and divide into a tumour
What is a tumour suppressor gene in normal cells?
In normal cells, tumour suppressor genes actively prevent cell growth
What is a tumour suppressor gene in cancer cells?
When mutated, these genes no longer stop a cell from growing
Which tumour suppressor gene is most commonly defective in human tumour cells?
p53
What are DNA repair genes in normal cells?
Repair and maintain DNA and correct errors
What are DNA repair genes in cancer cells?
Mutations in oncogenes and tumour suppressor genes are not repaired, driving cancer progression
What are apoptosis genes?
Faulty cells usually self-destruct through apoptosis to prevent cancer cells from forming. If they become mutated, a faulty cell can survive and grow into cancer
What is a DNA sequence mutation?
Changes to the sequence of nucleotides in DNA