2.4 - Disruption To The Regulation Of The Cell Cycle

Question 1

Proto-Oncogenes

Answer 1

stimulate cell division; when mutated become cancer causing oncogenes

Question 2

Oncogenes (What Happens)

Answer 2

• mutation causes a gain in function; oncogenes cause the rate of mitosis to increase.
• act in a dominant manner; the mutation of one copy of a pair of genes is sufficient to cause disease

Question 3

Tumour Supressor Genes

Answer 3

prevent cancer by slowing down cell division

Question 4

Tumour Supressor Genes Mutated

Answer 4

• mutation causes a loss of function; failure to slow the rate of mitosis, which continues unregulated.
• act in a recessive manner; both copies of a pair of genes must be affected to cause disease

Question 5

Carcinogen

Answer 5

is a cancer causing agent. Carcinogens may chemical, physical or biological in nature

Question 6

Risk Factors For Cell Cycle Disruption

Answer 6

• a weak immune system that is unable to detect and destroy cancer cells
• inheritance of an oncogene or missing / faulty tumour-suppressor gene
• environmental carcinogens may act as mutagens, damaging the DNA in proto-oncogenes and tumor suppressor genes

Question 7

Physical Mutagen

Answer 7

cause DNA damage through physical factors, often leading to structural changes in the DNA molecule. Ex: heat, ionizing radiation (X-rays, Gamma rays)

Question 8

Chemical Mutagen

Answer 8

alter DNA structure by interfering with base pairing, causing incorrect DNA replication. Ex: smoking, gas

Question 9

Biological Agent

Answer 9

are living organisms or viruses that alter DNA by inserting their genetic material into the host genome. Ex: Viruses, Bacteria