causes Flashcards
the AMES test
the Ames test is how we can work out whether something is a mutagen
or not.
- So we take any compound that we want to test and we mix it with a rat liver.
- this is so that we end up with not just the chemical itself but also its metabolites
- we mix them together. We get the mixture of the compounds and its metabolites. We grow it on to Bacteria that are normally not able to grow on that Medium
- if they get mutations and those mutations caused them to be able to grow we can count those colonies that grow up and we can use that as a measure of how mutagenic something is.
positives of the AMES test
- quick and inexpensive
- high throughput
- uses well established model organism: salmonella typhimurium
- simple to perform
- reliable
- non animal
limitations of AMES tests
- limited predicitve power: indicate whether a chemical is mutagenic, cannot predict toxicity
- may not detect all mutagens - only screens for mutagens that cause framshift mutations
- may not detect all mutagens - some chemicals that are mutagenic in higher organisms may not cause mutations in the bacteria
- may give false positives
- may not detect all mutagens: anything toxic and kills bacteria is not assessed for mutagenicity
heterogeneity
multiple clones - distinct genetic mutations, growth patterns and response to treatment
genetic heterogeneity - different phenotypes, including differences in cell behaviour, drug resistance, and growth rate
complex evolution - evolve over time through selection, leading to dominant clones and the extinction of less robust clones
diagnostic problems - the genetic heterogeneity of polyclonal cancers make characterising a cancer harder
difficult in treatment - different clones may respond to different treatments
uv damage
UV interaction causes crosslinking
- This crosslinking then creates 2 nucleotides which are joined together
- So when it comes to be replicated it cannot be recognised as one
- Leads to double stranded breaks
