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: 2646

#SCPH28 | Zoology

How many stem loop structures play important role in complete system of tryptophan gene regulation?

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#Question id: 9162

#SCPH28 | Zoology

If the direction of Earth's rotation reversed, the most predictable effect would be ________.

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#Question id: 12909

#SCPH01 Biochemistry

According to the diagram, arrange the steps in correct order: 

1. DNA is then digested by the Cas9 nuclease at specific points on both DNA strands. 

2. Homologous recombination to repair the break and incorporate the new DNA sequence then follows. 

3.The nuclease Cas9 is targeted to DNA by a guide RNA consisting of a specific 20 nucleotide spacer/targeting sequence (crRNA).

 4. That identifies the DNA to be modified, linked to a trans-activating (tracrRNA) sequence necessary for the recruitment and stability of Cas9 nuclease.

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#Question id: 5530

#SCPH01 Biochemistry

 The cavity inside the blastula is called the

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#Question id: 353

#SCPH05 I Biotechnology

Measurements show that the pH of a particular lake is 4.0. What is the hydrogen ion concentration of the lake?