Potential Mutagens Essay Research Paper Ames testObjective

Potential Mutagens Essay, Research Paper

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Ames trial


& # 8220 ; A mutagen is a chemical that mutates or alters DNA. & # 8221 ; Many times, mutagens may be carcinogens as they may bring on malignant neoplastic disease. Dr. Bruce Ames developed a method by utilizing specific mutant strains of the bacteriums Salmonella typhimurium to observe mutagens and possible carcinogens. This lab will prove assorted possible mutagens utilizing Dr. Bruce Ames process and methods.


Salmonella typhimurium is a prototrophic bacteria, which merely means that it can last on its ain every bit long as it has a beginning of energy, a C beginning, and inorganic salts. For the experiment, the auxotrophic signifier of salmonella is used. This mutated version can non synthesise the amino acerb histidine. Growth of this type of bacteriums will merely turn if hidtidine is added to the median or if the mutant occurs which corrects the original mutant. The latter is known as a back mutant or a reversion, where the mutant causes the bacterium to return to its wild type province. This type of mutant is either brought approximately by normal reproduction mistakes, or by mutagenesis, due to the action of a mutagen. This experiment will utilize four different strains of the bacteriums salmonella ( see table 1 ) . Each strain has a alone mutant, but they all lack the ability to bring forth histidine ( His- ) . This trial is applied to mensurate the ability of chemicals, which may be possible mutagens, that convert the His- bacterium to His+ , therefore bring forthing twice the figure of settlements in a His- environment as compared to the figure that occur spontaneously.


Several petri dishes were prepared each incorporating 1ml of melted soft agar, 60 milliliter of a certain type of bacteriums, and 20 milliliter of a possible mutagen. The dishes were incubated for 72 hours and eventually observed. Table 2 gives the overall consequences of the possible mutagens. From these consequences, it was determined that the cough bead in bacteriums TA98 ( see table 1 ) had produced more than two times the figure of settlements formed when compared to both the negative ( H2O ) and positive ( sodium azide ) controls. Therefore, the cough bead was used to farther trial this chemical as a possible mutagen. Ten more petri dishes were set up each 1 with a different concentration of possible mutagen ( cough bead ) to H2O. They were set up utilizing TA98 from of salmonella. Two petir dishes were prepared incorporating 100 % of the cough bead, another two incorporating a H2O, another two degree Celsius

ontaining a mixture of 50/50 cough bead to H2O, another two incorporating a mixture of 40/60 cough bead to H2O, and another incorporating 70/30 cough bead to H2O severally. The consequences are observed in table 3, which shows a dislocation of how the settlements developed. Ironically, the 100 % cough bead incorporating gel did non bring forth far more settlements than did the negative control as would hold been expected when comparing these consequences with table 2. The same is observed in the different concentrations of cough bead to H2O. The positive and negative controls help to compare and contrast in order to find whether a certain chemical is a possible mutagen or non. If medians, which contained histidine, were used, settlements would hold grown for all chemicals tested including the negative control and would look as a positive trial as a mutagen.


Overall, the Ames trial does assist to find whether chemicals are mutagens or non. The first portion of the experiment, giving consequences for table 2 gave a good indicant on what a possible mutagen may be. Yet, the farther rating of that peculiar chemical, which consequences can be found on table 3, did non bring forth consequences, which would set up that peculiar chemical as a mutagen.

Table 1: Mutant types of Salmonella used for proving different chemicals

Mutated Salmonella Type Description of Mutation

TA97a Frameshift mutant ( omission ) in the hisC cistron

TA98 Frameshift mutant ( interpolation ) in the hisD cistron

TA100 Base permutation in the hisG cistron

TA102 Nonsense mutant in the hisG cistron

Table 2: Consequences for proving possible mutagens

Potential Mutagen TA97a TA98 TA100 TA102

Sodium azide 3 300+ 25 53

Water 37 10 20 35

Dye 38 3 20 17

Sunny Delight 6 1 25 14

Sugar free cookies 32 45 40 48

Cough drops 36 400+ 25 62

Table 3: Consequences for proving the cough bead as a possible mutagen

Petri Dishes Containing Mutagen Number of settlements

1 ( 100 % cough bead ) 98

6 ( 100 % cough bead ) 105

2 ( H2O ) 78

7 ( H2O ) 65

3 ( 50/50 cough drop/water ) 80

8 ( 50/50 cough drop/water ) 60

4 ( 40/60 cough drop/water ) 74

9 ( 40/60 cough drop/water ) 50

5 ( 70/30 cough drop/water ) 43

10 ( 70/30 cough drop/water ) 50


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