Identify the purpose of and outline the procedure for the Ames test.

-

Identify the purpose of and outline the procedure for the Ames test.



purpose: access chemicals for their ability to cause mutations
1. two cultures are prepared of salmonella bacteria that have lost the ability to synthesize histidine (histidine-dependent)

2. the suspected mutagen is added to the experimental sample only; rate liver extract (an activator) is added to both samples

3. each sample is poured onto a plate of medium lacking histidine. the plates are then incubated at 37 degrees Celcius for two days. only bacteria whose histidine-dependent phenotype has mutated back (reverted) to histidine-synthesizing will grow into colonies

4. the number of colonies on the experimental and control plates are compared. the control plate may show a few spontaneous histidine-synthesizing revertants. the test plates will show an increase in the number of histidine-synthesizing revertants if the test chemical is indeed a mutagen and potential carcinogen. the higher the concentration of mutagen used, the more revertant colonies will result

Comments

Post a Comment

Popular posts from this blog

JAD Advantages and Disadvantages

-
JAD Advantages and Disadvantages : Compared with traditional methods, JAD is more expensive and can be cumbersome if the group is too large relative to the size of the project. Many companies find, however, that JAD allows key users to participate effectively in the requirements modeling process. Read:  What is JAD and how are users involved? What are advantages and disadvantages of JAD? When users participate in the systems development process, they are more likely to feel a sense of ownership in the results, and support for the new system. When properly used, JAD can result in a more accurate statement of system requirements, a better understanding of common goals, and a stronger commitment to the success of the new system. More:  RAPID APPLICATION DEVELOPMENT
Read more

What is JAD and how are users involved? What are advantages and disadvantages of JAD?

-
What is JAD and how are users involved? What are advantages and disadvantages of JAD? Joint application development, is a popular fact finding technique that brings users into the development process as active participants. Users have a vital stake in the information system, and should participate fully in the development process. They are/should be involved at every stage of development. Advantages : Users can participate effectively in the requirements modeling stage. More accurate statement of systems requirements, better understanding of common goals and stronger commitment to success of the new project Disadvantages : More expensive, can be cumbersome if the group is too large for the project.
Read more

According to Hero (1992), how are the three major theories of government compared in their ability to help explain the relative position of racial and ethnic groups in US politics? Do you agree that the theory of two-tiered pluralism is better than the other two in explaining the Latino (and other nonwhite) position in the post-1965 era?

-
According to Hero (1992), how are the three major theories of government compared in their ability to help explain the relative position of racial and ethnic groups in US politics? Do you agree that the theory of two-tiered pluralism is better than the other two in explaining the Latino (and other nonwhite) position in the post-1965 era? Answer: Pluralism : if citizens participate, electoral and policy outcomes will result that are favored by participants pluralism sees racial minority groups as just another interest group that needs to bargain and compromise to see change  if a group cannot enter the political arena, there are other channels through which that group can enter (according to pluralism) Coalitional Bias : modification of elite theory which states that only the top tier of people get the get opportunity socioeconomic inequality puts people in a more or less advantageous place to affect policy  links issues of class with racial issues  relationship b...
Read more