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?

TLS Online TPP Program

#Question id: 19792

#Unit 13. Advances in Biotechnology

Expression of BtR175 gene in mammalian cells enables Cry1Aa to bind the cells and cause their lysis. The specificity seems to be lost upon reduction of which amino acid residues of the protoxin, but can be restored by reoxidation of these residues?

TLS Online TPP Program

#Question id: 19793

#Unit 13. Advances in Biotechnology

The specificity of cry protein seems to be lost upon reduction of which amino acid residues of the protoxin, but can be restored by reoxidation of these residues?

TLS Online TPP Program

#Question id: 19794

#Unit 13. Advances in Biotechnology

The specificity of cry protein is lost upon reduction of cysteine residues of the protoxin, but can be restored by

TLS Online TPP Program

#Question id: 19795

#Unit 13. Advances in Biotechnology

Expression of BtR175 gene in mammalian cells enables Cry1Aa to bind the cells and cause their lysis. But upon what process this specificity can get lost?

TLS Online TPP Program

#Question id: 19796

#Unit 13. Advances in Biotechnology

The toxicity of cry protein toxins can be increased by the following approaches

1. Site directed mutagenesis within the toxin encoding region

2. Production of hybrid cry genes by fusing selected toxin domains of two or more different cry genes

Which of the following approaches could be correct?

TLS Online TPP Program

#Question id: 19797

#Unit 13. Advances in Biotechnology

 Which type of cry genes are used for the production of transgenic plants