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Which substance appears to become a mutagen when metabolized? Which substance becomesa less potent mustagen when metabolized?
Dish 1 Nothing added/15 colonies
Dish 2 Substance A /15 colonies
Dish 3 Substance B /85 colonies
Dish 4 Substance C/15 colonies
Dish 5 Substance A + liver extract/ 55 colonies
Dish 6 Substace B + liver extract/ 75 colonies
Dish 4 Substance C + liver extract /15 colonies

2007-03-19 08:10:06 · 2 answers · asked by daoudi2287 1 in Science & Mathematics Biology

2 answers

Substance A becomes a mutagen when metabolized and substance B is less potent when metabolized.

The Ames test relies on reversion, so the more colonies, the more mutagenic

2007-03-19 08:29:08 · answer #1 · answered by btpage0630 5 · 0 0

The Ames Test:

A while ago Ames discovered that bacteria need various vitamins to survive. He also discovered bacteria that do not need any vitamins to survive (these have the ability to synthesize their own). Bacteria that make their own vitamins do better and so they grow more colonies.

When you take bacteria that need vitamins to grow, and put them in a dish without those vitamins, they don't grow so well. (So you observe only a few colonies).

If you put in a mutagen, the mutagen may cause something called a back mutation that restores the bacteria's ability to make its own vitamins.

The number of back mutations that occurs is the same as the number of new colonies that spring up.

Ok, lets apply this to your case.

Now substance A shows 15 colonies in a regular medium (not enriched with vitamins). When you add vitamins, the substance becomes mutagenic, causing back mutations. Substance A becomes mutagenic when you add vitamin (liver extract) because the bacteria no longer eats substance A (and no longer render it less toxic by digestion) since they have such a ready supply of vitamins.

Substance B shows a lot of mutagenic potential (85 colonies), and with the liver extract, it shows fewer colonies because back mutations are less favorable adaptations when vitamins are readily available.

Substance A becomes a less potent mutagen when metabolized. Substance B is the most potent mutagen. Substance C has no mutagenic potential.

2007-03-19 08:31:02 · answer #2 · answered by Anonymous · 0 2

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