Question

The function of the selectable marker is
A. Identify ori site
B. To destroy recognition sites
C. Eliminating transformants and permitting non-transformants
D. Elimination of non-transformants and permitting transformants

Answer 1

Hint: The selectable markers are the sequence of a gene, whose expression allows us to identify whether the vector is introduced into the host cell or not.

Complete step by step answer: A selectable marker is one of the features in a vector. They are also called the reporter gene. These markers are an antibiotic resistance gene. These genes help us to indicate whether the host cell contains the foreign DNA (gene of interest). Suppose, the vector has the gene of interest. Now we want this gene of interest in huge quantities. Therefore we introduced this vector into the host cell, that is bacteria. So we want to know whether the bacteria contain the vector or not. In this condition, the selectable marker plays an important role to identify whether transformation took place or not. As we know that selectable marker is antibiotic resistance. Now will grow the host or bacteria into the culture that has antibiotics like ampicillin. So the bacteria that have a vector (transformant cell)will grow due to the presence of antibiotic resistance ampicillin, while other bacteria (non-transformant) that do not have vectors will die.
Hence the selectable marker helps in identifying and eliminating non-transformant and permitting the transformant to grow.
Therefore the correct option is D.

Note: Transformation is the process by which the vector or piece of DNA is introduced into the host cell. The host cell that carries that piece of DNA is called a transformant cell and the host which does not carry the piece of DNA is called non-transformant.