Question

An antibiotic resistance gene in a vector usually helps in the selection of

• A. Non-competent cells
• B. Competent cells
• C. Transformed cells
• D. Non-recombinant cells

Answer 1

The Correct Option is C

In molecular biology, vectors are used to transfer foreign DNA into host cells for various purposes, such as cloning or expressing genes of interest. To ensure that the desired DNA has been successfully inserted into the host cells, a selectable marker is often included in the vector. The most common selectable markers are antibiotic resistance genes.

These antibiotic resistance genes provide a way to select for cells that have taken up the vector and acquired the desired DNA. The vector typically contains a gene that confers resistance to an antibiotic, such as ampicillin or kanamycin. When the vector is introduced into the host cells, the cells are typically grown in a medium containing the corresponding antibiotic. Only the cells that have successfully incorporated the vector, along with the antibiotic resistance gene, will be able to survive and grow in the presence of the antibiotic.

Therefore, the presence of an antibiotic resistance gene in a vector allows for the selection and growth of transformed cells that have taken up the vector and acquired the foreign DNA.

Answer 2

In the context of genetic engineering, vectors are used to carry foreign DNA into host cells. A crucial component of many vectors is an antibiotic resistance gene. This gene does not directly confer resistance to the host cell, but rather plays a vital role in identifying cells that have successfully taken up the vector. 

Therefore, an antibiotic resistance gene in a vector primarily aids in the selection of:

Transformed Cells

Transformed cells are those that have successfully incorporated the vector (and the foreign DNA it carries). By growing cells on a medium containing the antibiotic, only cells containing the vector (and thus the resistance gene) will survive. This allows researchers to easily distinguish and select for these successfully transformed cells.