Recessive and dominant mutations

Question 1

What happens in a normal human cell?

Answer 1

Normally human cells grown and divide to form new cells as the body needs them. When cells grow old or become damaged, they die and new cells take place

Question 2

What is cancer?

Answer 2

Cancer is a collection of related disease and can start almost anywhere in the body. Cancer cells are cells within a tissue that no longer respond to many of the signals that control cellular growth and death. They become increasingly resistant to the controls and divide more rapidly

Question 3

How does cancer spread?

Answer 3

Despite multiple abnormality’s cancer cells evade programmed cell death, in late stages of cancer, cells break through normal tissue boundaries and metastasise to new sites in the body

Question 4

How does cell division affect cancer?

Answer 4

Cancer is the result of an accumulation of mutations. Most mutations associated with DNA replication. The more times a cell divides the more likely it is to gain a mutation hence incidence of cancer greatly increases with age

Question 5

What mutations are related to cancer?

Answer 5

Hundreds of genes encode proteins that normally regulate cell growth and division. Mutations that alter these genes in somatic cells can lead to cancer. Mutations can be spontaneous or the result of exposure to mutagens

Question 6

What are tumour suppressor genes?

Answer 6

Encode proteins that normally prevent uncontrolled cell growth e.g. proteins that inhibit cell division and prevent other mutations (DNA repair enzymes). Lack of these genes can stimulate cell growth - recessive mutations promote cancer

Question 7

What are onco-genes?

Answer 7

Encode proteins that promote cell growth e.g. proteins that stimulate cell division. Cancer mutations increase activity of these genes. Dominant mutations promote cancer

Question 8

Cancer treatments

Answer 8

Surgery to remove cancer cells. Radiation therapy which targets and kills cancer cells. Chemotherapy uses drugs that target dividing cells as cancer cells grow and divide rapidly but also affects normal cells. Target therapy uses drugs that targets changes in cancer cell that allow them to grow and divide