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.

Next, you isolate a third mutant, MelC–, which gives constitutive melibiase expression. The MelC– mutation is closely linked to Mel1 and MelB–. Genetic tests of the MelC– mutation yield the following:

 

As above, classify the MelC– mutation in terms of its basic genetic properties and explain how you arrived at your conclusions.

TLS Online TPP Program

#Question id: 17279

#Unit 13. Methods in Biology

Which of the following is relatively more stable to heat

TLS Online TPP Program

#Question id: 17280

#Unit 13. Methods in Biology

During DNA isolation, phenol / chloroform extraction is performed to remove

TLS Online TPP Program

#Question id: 17654

#Unit 13. Methods in Biology

The protein concentration in DNA extraction sample measured by

TLS Online TPP Program

#Question id: 17655

#Unit 13. Methods in Biology

In DNA isolation, for protein free solution what will be the ratio at  nm

TLS Online TPP Program

#Question id: 17659

#Unit 13. Methods in Biology

During your study of the gene for an enzyme you have isolated an amber mutation in the middle of the gene which produces a truncated form of the enzyme. By placing a +1 frameshift mutation a short distance before the amber mutation and a –1 frameshift mutation a short distance after the amber mutation you create a triple mutant that restores expression of a functional, full-length enzyme. 

a) +1 frameshift puts the amber mutation out of frame so that it is no longer read as a stop.

b) -1 frameshift is inserted after the amber so that no longer read as a stop.

c)  -1 frameshift is inserted after the amber to restore the frame of the end of the protein.

d) +1 frameshift puts the amber mutation out of frame so that it restore the frame of the end of the protein.

Which of the following is the correct prediction about the frame shift mutation?

TLS Online TPP Program

#Question id: 17819

#Unit 13. Methods in Biology

During RNA extraction, the homogenate is first treated with