You are studying a new strain of E. coli that can utilize the disaccharide melibiose very efficiently. You find that utilization depends on the enzyme melibiase, which is encoded by the gene Mel1. Mel1 is not expressed unless melibiose is present in the growth medium. Explain the two regulatory pathways for Mel1 that can explain the behavior of the MelA– and MelB– mutations. For each regulatory pathways what is a role for the inducer melibiose?

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#Question id: 1438

#Unit 4. Cell Communication and Cell Signaling

The first line of defense against point mutations is:

TLS Online TPP Program

#Question id: 1439

#Unit 4. Cell Communication and Cell Signaling

Indirect-acting carcinogens are those that:

TLS Online TPP Program

#Question id: 1440

#Unit 4. Cell Communication and Cell Signaling

Which of the following is NOT evidence that smoking causes lung cancer?

TLS Online TPP Program

#Question id: 1441

#Unit 4. Cell Communication and Cell Signaling

If colon cancers could be prevented by intervening in the earliest molecular changes during multi-hit progression, the molecule you would target for intervention would be:

TLS Online TPP Program

#Question id: 1442

#Unit 4. Cell Communication and Cell Signaling

Transgenic mice that express an activated oncogene like rasD under the control of the TetOFF system are likely to undergo which of the following events when tetracycline is given?

TLS Online TPP Program

#Question id: 1443

#Unit 4. Cell Communication and Cell Signaling

Which of the following is(are) a tumor suppressor gene?