Restriction enzymes should not have more than one site of action in the cloning site of a vector. Comment.
If the restriction enzymes have more than one recognition site in a vector, then the vector itself will get fragmented on treatment with the restriction enzymes.
What does 'competent' refer to in competent cells used in transformation experiments?
DNA being a hydrophilic molecule can not pass through cell membranes. Therefore, the bacteria should be made competent to accept the DNA molecules.
Competent means bacterial cells, on treatment with chemicals like $\mathrm{CaCl}_2$, are made capable of taking up foreign DNA.
What is the significance of adding proteases at the time of isolation of genetic material (DNA)?
Proteases degrade the proteins present inside a cell (from which DNA is being isolated). If the proteins are not removed from DNA preparation then they could interfere with any downstream treatment of DNA.
While doing a PCR, 'denaturation' step is missed. What will be its effect on the process?
If denaturation of double-stranded DNA does not take place then primers will not be able to anneal (joining) to the template. Hence, no extension will take place and after are there will be no amplification.
Name a recombinant vaccine that is currently being used in vaccination program.
Hepatitis-B recombinant vaccine (engerix) is used for vaccination of hapatitis virus.