Q21 of 42 Page 1

Give reasons why:

(a) DNA cannot pass into a host cell through the cell membrane.


(b) Proteases are added during isolation of DNA for genetic engineering.


(c) Single cloning site is preferred in a vector.


a) Since the bacterial cells must be made ‘competent’ to take up DNA. When the cell is not competent, the DNA cannot pass into a host cell through the cell membrane.


b) To remove proteins, the proteases are added during the isolationof DNA for genetic engineering.


c) The presence of more than one recognition site within vector will create several fragments, which complicate the gene cloning process avoids that the single cloning site is preferred in a vector.


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