Read the following statements regarding the features of cloning vectors.

(i) The origin of replication is also responsible for controlling the copy number of the linked DNA.

(ii) In addition to ori site, the vector requires selectable markers, which help in identifying and eliminating non-transformants and selectively permitting the growth of the transformants.

(iii) The vector needs to have at least single recognition site for the commonly used restriction enzymes.

(iv) Presence of more than one recognition sites within the vector for one restriction enzyme will generate several fragments which will facilitate the gene cloning.

How many of the above statements are correct?

1

2

3

4

The correct number of statements regarding the features of cloning vectors is 3. Statements (i), (ii), and (iii) are accurate, while statement (iv) is misleading in the context of gene cloning. Therefore, the choice is 3 .
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Answered by Anonymous | 2025-07-04

Cloning vectors are essential tools in molecular biology used to insert foreign DNA into host cells for replication and study. Let's evaluate each statement to determine how many are correct:

The origin of replication is also responsible for controlling the copy number of the linked DNA.

This statement is correct. The origin of replication (ori) in a vector not only initiates the replication process but also influences how many copies of the vector, and hence the foreign DNA, are produced within the host. This control over copy number is crucial for maintaining efficiency and balance within the cell.


In addition to ori site, the vector requires selectable markers, which help in identifying and eliminating non-transformants and selectively permitting the growth of the transformants.

This statement is also correct. Selectable markers are genes integrated into the vector, like antibiotic resistance genes, that allow researchers to distinguish between cells that have taken up the vector (transformants) and those that haven't (non-transformants). Only cells with the vector will survive and grow in a medium containing the antibiotic.


The vector needs to have at least a single recognition site for the commonly used restriction enzymes.

This statement is correct. A cloning vector should have one or more unique recognition sites for restriction enzymes. These sites are necessary for inserting foreign DNA at a specific location within the vector without disrupting essential functions of the vector.


Presence of more than one recognition site within the vector for one restriction enzyme will generate several fragments which will facilitate the gene cloning.

This statement is incorrect. The presence of multiple recognition sites for the same enzyme within a vector makes cloning harder because cutting at multiple sites will produce multiple fragments, complicating the ligation process.



Thus, three out of the four statements are correct.

Answered by BenjaminOwenLewis | 2025-07-06