oncogenes Flashcards
what is the definition of an oncogene?
a gene mutated such that its protein product is produced in higher quantities or has increased activity and so acts in a dominant manner to initiate tumour formation
what are driver mutations?
mutations which contribute to the development of cancer hallmarks
what are passenger mutations?
mutations which have no effect on cancer development
how do driver mutations contribute to cancer development?
the may alter the amino acids in a protein important in regulating hallmark or alter the expression of a gene involved in regulating hallmarks
may cause an increase in activity or levels of cell proliferation factor through oncogenes
may decrease activity or levels of factor that supress cell growth and/or promotes cell death through tumour suppressor genes
why do passenger mutations not contribute to cancer development?
the mutation may occur in non-coding regions, occur in coding regions but are silent mutations or may alter the amino acid chain but the protein is not involved in regulating cancer hallmarks
what are risk factors that cause DNA damage?
radiation chemotherapy environment lifestyle (eg smoking) genetics age
which hallmarks are linked to oncogenes?
sustaining proliferative signalling
which hallmarks are linked to tumour suppressor genes?
evading growth suppressors
resisting cell death
what is the definition of proto-oncogenes?
the non mutated version of the gene
what is the function of proto-oncogenes?
regulate various aspects of cell growth and division
what mutations can cause a proto-oncogene to become an oncogene?
translocation or transposition can lead to a new promoter which is more active causing normal growth-stimulating proteins to be produced in excess
gene amplification causes production of more copies of the gene leading to increased production of the normal growth-stimulating protein
point mutation within a control element and within the gene can cause overproduction of the protein
