Question

Assertion: All expression vectors are cloning vectors and vice-versa.
Reason: Expression vectors have at least the regulatory sequence, i.e., promoters, operator, ribosomal binding sites, etc, having optimum function in the chosen control but not origin of replication.

A. Both assertion and reason are correct and reason is the correct explanation for assertion.
B. Both assertion and reason are correct but reason is not the correct explanation for assertion.
C. Assertion is correct and reason is incorrect.
D. Both assertion and reason are incorrect.

Answer 1

Hint: Assertion and reasons can be explained by joining both the points together and seeing the similarities or the immediate link between the given points. Here, the point is about the expression vector.

Complete Answer:
- Cloning vectors are very useful for developing many copies of the gene. Expression vectors are associated with the actual expression of the gene into mRNA and protein in the target organism.
- Cloning vectors are usually which contain features related to the insertion or removal of DNA fragments. There are so many types of cloning vectors, but most commonly used ones are genetically engineered plasmids. Cloning is generally first performed using E.coli, and cloning vectors in E.coli include plasmids, bacteriophages, cosmids and bacterial artificial chromosomes.
- Expression vectors have at least the regulatory sequences, i.e., promoters, operator ribosomal binding sites,etc having the optimum function in the chosen control but not origin of replication. The vector is used to introduce a specific gene into a target cell, and can command the mechanism of the cell for protein synthesis to produce the protein encoded by the gene.
- The vector is engineered to have regulatory sequences that act as enhancer and promoter regions and lead to efficient transcription of the gene which is lifted on the expression vector.

Hence, the correct answer is option (D). Both assertion and reason are incorrect.

Note: An Expression vector must have elements necessary for gene expression. These consist of a promoter, the correct translation initiation sequence such as a ribosomal binding site and start codon, a termination codon, and a transcription termination sequence.