Cancer Flashcards
define multifactorial disease
many genetic and environmental factors contribute to the risk of developing a disease
what is cancer and how is it formed
disease that is the result of uncontrolled cell division that creates a tumour which is made of mutated cells which destroy surrounding tissue
what factors cause cancer
damage to the DNA-
physical factors e.g. UV light, asbestos
mutations occurring when cells divide
Epigenetic changes-
DNA methylation
when does cancer occur
when the rate of cell multiplication is faster than cell death and a tumour grows
(often in tissues with a high rate of mitosis e.g. lungs, bowl, gut and bone marrow
steps of cancer formation
-environmental mutations increase the risk (UV, radiation carcinogens)
-mutations occur in DNA of tumour repressor gene or protooncogenes which control the cell cycle
-cell cycle disrupted as there are no breaks (checkpoints) on cell cycle anymore
-leads to uncontrolled cell division and shorter interphase
-lack of apoptosis so rate of cell multiplication is greater than cell death
-abnormal mass of unspecialised cells (tumour) forms which could invade tissue
-cells do not become specialised so growth cannot be controlled
what are protooncogenes and what do they code for
code for proteins that stimulate cell cycle progression/regulate the cell cycle
what can mutations in the protooncogenes cause
cause oncogenes to be formed
DNA mutations
protooncogenes ————————— oncogenes
epigenetic changes
what effect do oncogenes have on the cell cycle
cause the cell cycle to be continually active
what are tumour repressor genes and what do they code for
code for proteins that halt the cell cycle at G1/S phase
what do mutations in the tumour repressor genes cause
mutations in gene inactivate the gene so they are not expressed
means there is not stops/breaks (checkpoints) in the cell cycle
what are some controllable factors that cause cancer
UV light
tobacco (carcinogens in the tar)
asbestos
diet (low antioxidants, nitrates)
radiation
some viral infections (HPV, cervical cancer)
how cancer be spread to other tissues
some cancer cells break off a tumour and travel to other parts of the body in the lymph or the blood
causes secondary tumours in other parts of the body
