Study the following statements regarding recombinant DNA technology and select the incorrect ones. (i) Taq polymerase extends the primers using the nucleotides provided in the reaction. (ii) Antibiotic resistance genes are considered as desirable genes in recombinant DNA technology. (iii) DNA fragments are separated according to their charge only, in agarose gel electrophoresis. (iv) Transformation is a procedure through which a piece of DNA is integrated in to the genome of a host bacterium. (v) To produce higher yields of a desired protein, host cells can be multiplied in a continuous culture. (vi) Downstream processing is one of the steps of polymerase chain reaction.

The DNA that helps carry the target DNA fragment to the host cell for cloning.

Assertion : A piece of DNA inserted into an alien organism generally does not replicate if not inserted into a chromosome. Reason : Chromosomes have specific sequences called ori region where DNA replication is initiated.

Which of the following statements are correct ? (i) Restriction enzymes cut the strand of DNA a little away from the centre of the palindrome site, but between the same two bases on the opposite strands. (ii) Hind ll always cuts DNA molecules at a particular point by reconginisng a specific sequence of six base pairs. (iii) Separated DNA fragments cannot be visualised without staining on an agarose gel electrophoresis. (iv) 'Ori' is the sequence responsible for controlling the copy number. (v) DNA is a positively charged molecule.

In a polymerase chain reaction after the denaturation step why the mixture needs to cool down to a lower temperature ? a) To permit specific annealing of the primers b) To give a halt to the reaction mixture c) To increase the activity of enzyme Taq polymerase d) To obtain the multiple copies of the DNA

The base sequence in one of the strands of DNA is TAGCATGAT. (i) Give the base sequence of the complementary strand. (ii) How are these base pairs held together in a DNA molecule? (iii) Explain the base complementarity rule. Give the name of the scientist who framed this rule?

The different steps of recombinant DNA technology are given below randomly. (i) Isolation of the DNA fragments or genes to be cloned (ii) Introduction of the recombinant DNA into a suitable cell (usually E. coil) called host (transformation) (iii) Multiplication/expression of the introduced gene in the host (iv) Selection of the transformed host cells, and identification of the clone containing the desired gene/DNA fragment (v) Insertion of the isolated gene in a suitable plasmid vector Which of the following represents the correct sequences of steps ?

Read the following statements and select the correct ones. (i) Same kind of sticky ends are produced when a DNA has been cut by different restriction enzymes. (ii) Exonucleases make cuts at specific positions within the DNA. (iii) Hind ll was the first restriction endonuclease to be isolated. (iv) A bacteriophage has the ability to replicate within bacterial cells by integrating its DNA with bacterial DNA. (v) Presence of more than one recognition sites for a enzyme within the vector facilitates the gene cloning.