Question

Selectable markers are present in

• A. Antibiotics
• B. Antibiotic resistance gene
• C. Vector
• D. Host

Answer 1

The correct option is C Vector

Vector
Vectors are the DNA molecules which can carry the foreign DNA fragment into the host cells for cloning. Examples include plasmids.

Selectable marker
Selectable marker is a gene in a vector that helps in the selection of transformants (host cells which have successfully taken up the foreign DNA) and non-transformants (cells which have not taken up the vector DNA).
For example, antibiotic resistance genes in the vector.

Host
Hosts are the organisms in which the genes of interest are introduced with the help of vectors for expression.
For example, Escherichia coli acts as a host and produces the human protein insulin.

Antibiotic resistance gene
Antibiotic resistance gene is a type of selectable marker to separate the transformed cells from the non-transformants after cloning. Alien gene is inserted at this site. The cells are then placed on the growth medium with the respective antibiotics that retards their growth, hence they can be separated from the non-transformants.

Antibiotics
Antibiotics are the chemical substance obtained from the bacterial cells which they produce against other microorganisms for their self defense.

Final answer
(A) Vector