Recombinant DNA Technology MCQs

If bacterial cells are transformed with a mixture of linear and circular molecules resulting from a ligation reaction designed to produce a recombinant molecule

A recombinant protein is to be expressed under the control of the lac promoter and operator in a strain of E. coli having the genotype lacI+ crp+. Even in the absence of inducer IPTG, low levels of expression of the recombinant protein are seen (leaky expression). Which one of the following should be done to minimize such leaky expression?

Determine the correctness or otherwise of the following Assertion [A] and the Reason [R]. Assertion [A]: Dam methylase protects E. coli DNA from phage endonucleases. Reason [R]: E. coli Dam methylase methylates the adenosine residue in the sequence "GATC".

The schematic of a plasmid with a gap in one of the strands is shown below: Which of the following enzyme(s) is/are required to fill the gap and generate a covalently closed circular plasmid? P. DNA ligase Q. Alkaline phosphatase R. DNA polymerase S. Polynucleotide kinase

Match the following genetic elements with their functions. Genetic elements Functions P. neoR 1. Facilitates inducible expression of genes in eukaryotes. Q. SV40 2. Facilitates constitutive expression of genes in eukaryotes. R. LTR 3. Allows amplification of gene. S. S. dhfr. 4. Provides way of selecting eukaryotic cells, which have received foreign DNA.

cDNA made from the mRNA of an organism was used to make a cDNA library in a vector that allows the expression as a fusion with a reporter tag. What percentage of the cDNA clones is likely to give rise to correct gene products?

Commonly used reporter gene in plant expression vectors is

EcoRI restriction sites on a 10kb DNA fragment are shown below Upon partial digestion, what are the lengths (in kb) of all the possible DNA fragments obtained?

What are the experimental steps needed for screening an expression library for clone encoding a protein X that has been isolated and purified? P. mRNA isolation Q. Antibody preparation R. Cloning into an appropriate vector S. Western blotting on transferred plaques