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+