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.

You next construct a MelA– MelB– double mutant, which gives the following behavior:

 

Which of your two models is consistent with this new data?

a) the MelA- MelB- double mutant is identical to the MelB- mutant

b) MelA- is epistatic to MelB-

c) MelB- is epistatic to MelA-

d) the MelA- MelB- double mutant is identical to the MelA- mutant

Which of the following is the correct prediction about the double mutants?

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#Question id: 1912

#Unit 4. Cell Communication and Cell Signaling

Which of the following allogeneic grafts does NOT require immunosuppression?

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#Question id: 4406

#Unit 3. Fundamental Processes

An electrophoretic mobility shift assay (EMSA) was conducted to check for the binding of TFIIB to a segment of a DNA promoter region. Which of the following approaches could be used to confirm that TFIIB is indeed binding?

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#Question id: 1058

#Unit 4. Cell Communication and Cell Signaling

Phage-encoded enzymes are

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#Question id: 1969

#Unit 4. Cell Communication and Cell Signaling

A bacterium has elements on its surface that are resistant to lysozyme. If an individual is infected with this bacterium, what is a probable consequence?

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#Question id: 10642

#Unit 10. Ecological Principles

Which curve best describes survivorship in a songbirds and marine crustacean that molts respectively?