Microbiology Mutations and The Ames Test
What is Salmonella auxotroph strain?
A strain with a damaged anabolic pathway
Why does the Ames test use mutant strains of Salmonella
Because Salmonella cannot synthesis the amino acid histidine
Carcinogens
Cancer causing chemical agents
What do the Salmonella strains used in the Ames test lack?
Lipopolysaccaride coats, which makes they highly permeable to many substances.
What is the Ames Test?
Test in which special strains of bacteria are used to evaluate the potential of chemicals to cause cancer.
What is often used as one of the intial screens for potential drugs to weed out possible carcinogens?
The Ames test
What is the practical application of bacterial mutagenesis?
To detect mutagenic chemicals
Why did they use a small amount of rat liver in the ames test?
To mimic mammallian metabolism.
True or False: In the Ames test, false positives can occur.
True
True or False: The Salmonella strains used in the Ames Test had inactivated repair systems
True
True or False: There is a strong positive correlation between mutagenic and carcinogenic chemicals
True
Does exposure to a chemical produce mutations, some of which will be revertants of the auxotroph?
Yes, The more revertants, the stronger the mutagenic activity of the chemical
Salmonella typhimurium his- must__________
be grown in presence of histidine
Many noncarcinogens are _________ to carcinogens in the liver
converted
In the Ames test, we use a mixture of his- strains to ______
detect base changes, insertions and deletions.
Salmonella cannot grow without what added to the medium?
histidine
In the Ames test they are looking for revertant strains that are _______
no longer auxotropic (can grow without histidine). THese mutagenized cells are now his+
The ames test is very useful but not ______
perfect
Mutagen is placed in culture which causes________
some his- strains to revert to his+