Lecture 18 - what are recessive and dominant mutations Flashcards
what is a germline mutation
when a mutation occurs in a cell that goes on to make gametes (sperm or egg cells), the mutation can be passed on to the next generation
what is a somatic mutation
occur in other cells that can not be passed on
what is the maintenance of a cell like
- tightly controlled process
- balance between cell devision (growth) and cell death
what is the tissue where cancer cells are found
no longer respond to many of the signals that control cellular growth and death
what is cancer a result of
an accumulation of mutations, many of them associated with DNA replication
why does the risk of cancer increase with age
because the more times a cell divides the more likely it is to gain a mutation
what mutations can lead to cancer
mutations in somatic cells that alter the genes which encode proteins that normally regulate cell growth and division
what do tumor suppressor genes encode
they encode proteins that normally prevent uncontrolled cell growth
what type of mutation promotes cancer in tumor suppressor genes
recessive mutations promote cancer, meaning the mutation must be present in both gene copies
what do onco-genes encode
encodes proteins that promote cell growth
what type of mutation promotes cancer in onco genes
dominant proteins promote cancer
what does a cancer mutation in an onco gene do
increases the activity of the gene meaning increased cell growth
how does a mutation to a tumor suppressor gene lead to cancer
there is loss of function of RB gene or p16 gene which causes activation of the E2F transcription factor
when does uncontrolled cell division occur
when there are mutations in both copies of tumor suppressor genes a mutation to an onco gene
