Question

In the process of insertion inactivation_________
A. A recombinant DNA is inserted within the coding sequence of enzyme galactosidase resulting in the inactivation of the enzyme.
B. A recombinant DNA is inserted within the coding sequence of proteins involved in the replication of plasmid.
C. A recombinant DNA is inserted within the recognition site of EcoRI.
D. None of the above.

Answer 1

Hint: The incorporation of a DNA fragment into the vector leads to the inactivation of one more gene present on its genome and a characteristic coded by the inactivated gene will no longer be displayed by the host cells.

Complete answer:
In the process of insertional inactivation, a recombinant DNA is inserted within the coding sequence of enzyme galactosidase resulting in the inactivation of the enzyme.
Insertional inactivation technique of recombinant DNA technology used to select bacteria that carry recombinant plasmids; a fragment of foreign DNA is inserted into a restriction site within a gene for antibiotic resistance, thus causing that gene to become nonfunctional. It is often used to identify recombinant vectors in gene cloning and in turn to distinguish a recombinant vector from a non-recombinant vector. For example, insertion of a piece of foreign DNA into a cloning site which is located on an antibiotic-resistant gene on the vector can lead to loss of the antibiotic resistance phenotype by insertional inactivation. The recombinant vector will, therefore, specify antibiotic sensitivity, whilst the non-recombinant vector will specify antibiotic resistance.

So, the correct answer is 'A recombinant DNA is inserted within the coding sequence of enzyme galactosidase resulting in the inactivation of the enzyme'.

Note:
- Recombinant DNA Technology is defined as the joining together of DNA molecules from different organisms and inserting it into a host organism to produce new genetic combinations that show advanced and desirable characteristics.
- A plasmid can be seen as a small, extrachromosomal DNA molecule within a cell. It is not associated with chromosomal DNA and can replicate independently. It is present in bacteria, archaebacteria, and some of the eukaryotic organisms.