Why is the enzyme cellulase needed for isolating genetic material from plant cells and not from animal cells?

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(a)

Cellulase is used to digest the cell wall (cellulose) of plant cells; animal cell have no cell wall and hence, it is not needed.

Why is it essential to have a 'selectable marker' in a cloning vector?

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(a)

It helps in identifying the recombinants from the non-recombinants.

Restiction enzymes should not have mora than one site of action in the cloning site of a vector? Comment

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(a)

Presence of more than one recognition site will generate several segments and complicate the gene cloning.

Would you choose an exonuclease for producing a recombinant DNA molecule?

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(a)

No, because exonucleases will remove the nucleotides from the ends DNA molecule and not at any particular desired region.

Retroviruses are disease-causing microorganisms, even then are efficiently used in biotechnology experiments. Explain how is it possible?

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(a)

Retroviruses in which its disease-causing gene is removed (inactivated) can be used as vectors to deliver the recombinant/alien DNA into animal cells.

Why do DNA fragments move towards the anode during gel electrophoresis? If yes, explain.

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(a)

Yes, it is because DNA fragments are negatively charged. Hence, move towards the anode (positive charge).

Any DNA flanked at its two borders by T-DNA can be integrated into the plant genome. Name the vector used for this plant gene transfer?

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(a)

Tumor inducing plasmids (Ti Plasmids)

In making bacteria as a competent host for transformation with r-DNA, it is treated with a specific concentration of divalent cation like calcium. What is the role of calcium?

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(a)

Creates pores in its cell wall

Why are antibiotic-resistance genes used as markers in E.coli?

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(a)

It is because the normal E. coli cells do not have resistance to any such antibiotics.

A plasmid without a selectable.marker was chosen as vector for cloning a gene. How does this affect the experiment?

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(a)

In the absence of a selectable marker, it will not be possible to identify the recombinants from the non - recombinants.