If bacterial cells are transformed with a mixture of linear and circular molecules resulting from a ligation reaction designed to produce a recombinant molecule
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Biotechnology Engineering · all questionsRecombinant DNA Technology
Recombinant DNA Technology
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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?
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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".
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".
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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
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
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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. |
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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?
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Commonly used reporter gene in plant expression vectors is
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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?
Upon partial digestion, what are the lengths (in kb) of all the possible DNA fragments obtained?
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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
P. mRNA isolation
Q. Antibody preparation
R. Cloning into an appropriate vector
S. Western blotting on transferred plaques
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The basis for blue-white screening with pUC vectors is
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Phage T7 promoter containing plasmids are used for over-expression of cloned genes because
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Though the right border (RB) and left border (LB) of T-DNA are identical, the DNA transfer is specific for the DNA left of the RB (the T-DNA), rather than for the DNA left of the LB because
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The restriction endonuclease Eco52I recognizes the sequence C/GGCGG and cuts between the first C and the first G, indicated by the slash. DNA cut by which of the following enzymes (given with their recognition sequences and cut sites) could be cloned into a plasmid digested with Eco52I?
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Which of the following are commonly used as reporter genes?
P. NPTgene
Q. Luciferase gene
R. CFTR gene
S. GFP gene
P. NPTgene
Q. Luciferase gene
R. CFTR gene
S. GFP gene
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Which one of the following statements about Agrobacterium Ti plasmid is correct?
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Match the items in Group I with Group II.
| Group I (Vectors) | Group II (Maximum DNA packaging) |
| P. λ phage | 1. 35 - 45 kb |
| Q. Bacterial Artificial Chromosomes (BACs) | 2. 100 - 300 kb |
| R. P1 derived Artificial Chromosomes (PACs) | 3. ≤ 300 kb |
| S. λ cosmid | 4. 5 - 25 kb |
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A single base pair of DNA weighs 1.1 × 10-21 grams. How many picomoles of a plasmid vector of length 2750 bp are contained in 1 μg of purified DNA?
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Many plasmids have ampr marker. This implies
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Expression in poor amount and in inactive form of cDNA of a eukaryotic protein in Escherichia coli using its expression vector is due to
P. The absence of capping mechanism of mRNA.
Q. Codon bias.
R. Absence of polyadenylation.
S. Absence of proper glycosylation.
P. The absence of capping mechanism of mRNA.
Q. Codon bias.
R. Absence of polyadenylation.
S. Absence of proper glycosylation.
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T4 polynucleotide kinase is used for
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