Week 120 - Genes and Cancer Flashcards Preview

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Flashcards in Week 120 - Genes and Cancer Deck (17):

Why do cancers occur?

Majority due to mutations in the DNA that control cell growth and proliferation

A small proportion of cancers are thought to be inherited (~5%)


What is cancer?

A group of disorders that cause cells to:
- escape normal controls on cell division
- proliferate
- migrate from original site to other parts of body


What are the causes of cancer?

Genetic causes

Environmental causes (e.g. smoking)


What are the characteristics of cancer cells?

Cancer cells form tumours with growth, whereas normal cells form flat sheets of cells


What is transformation when talking about cancer?

A multi-step process where a cell's growth goes from being regulated to un-regulated leading to uncontrolled proliferation


What are the two types of mutations that occur?

Acquired mutations (somatic mutations)
- do not occur in germ line cells

Inherited mutations
- germ line mutations
- present in every cell in the body


What percentage of cancer deaths are associated with smoking?

50 - 60%


Which cancers is smoking strongly linked to?

Lung cancer

URT ccancer

Oesophageal cancer

Bladder cancer


List four things which are strongly related to cancer


Viruses (DNA viruses strongly linked)

Radiation (UVB from sun can damage DNA)

Oncogenes (mutated from proto-oncogenes)


Give a few examples of viruses that are linked to cancer

Cervical cancer - HPV 16 & 18

Liver cancer - Hep B and Hep C

Kaposi's sarcoma and lymphoma - HIV


Briefly list the phases of the cell cycle



Non-dividing cells go from G1 and remain in G0


List the three main actions during interphase

G1 = cell undergoes normal metabolism and prepares for S phase
- check 1: check correct size of cell and for DNA damage

S = DNA replication occurs
- check 2: checks whether DNA has replicated correctly

G2 = cell prepares for mitosis
- check 3: checks whether mitotic spindle has formed properly


What is the function of P53?

A tumour suppressor gene that targets cells with severe DNA damage => apoptosis

Note: mutations to P53 => loss of tumour suppression => unregulated cell growth


What is the function of telomerase, and how is it affected in cancer?

Increases the length of telomeres to inhibit cell senescence

Telomerase increases in cancer


Define penetrance

The proportion of individuals with a mutated gene that gain the disease


What is the effect of methylation of a gene?

Turns the expression of a gene off


What is the effect of acetylation of a gene?

Turns the expression of a gene on