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: 31343

#Unit 13. Methods in Biology

Which one of the following is the least sensitive immunoassay

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#Question id: 27559

#Unit 1. Molecules and their Interaction Relevant to Biology

Since the pK values for aspartic acid are 2.0, 3.9 and 10.0, it follows that the isoelectric (pH) is

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#Question id: 179

#Unit 1. Molecules and their Interaction Relevant to Biology

The average molecular weight of the 20 standard amino acids is 138, but biochemists use 110 when estimating the number of amino acids in a protein of known molecular weight.  Why?

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#Question id: 19334

#Unit 12. Applied Biology

Which one of the following sensors is also known as mass sensitive biosensor?

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#Question id: 1679

#Unit 4. Cell Communication and Cell Signaling

What is the molecular weight of MHC class II β chain?