Question

A piece of foreign DNA was inserted into a plasmid with an antibiotic resistance gene and lactose Z gene. The plasmid DNA was cut with a restriction enzyme, which splits the lactose Z gene and opens the circle. The foreign DNA was next inserted into the open restriction site of the plasmid. When the recombinant plasmid was introduced into bacterial cells and grown in the presence of antibiotics, some of the colonies turned blue in the presence of genes. The blue colonies contained
A. Plasmid only
B. Foreign DNA only
C. Both foreign DNA and plasmid
D. Neither plasmid nor foreign DNA

Answer 1

Hint: The process of selectively repeating any segment of DNA is called molecular cloning. This can be achieved by recombinant DNA technique or polymerase chain reaction.

Complete answer:
Recombinant DNA technology is a process in which DNA from two different species are joined together. The recombinant DNA is then administered into a host to develop new combinations.

This process completes in three steps in which the DNA is cut, joined and then inserted with the help of vectors.
A plasmid containing cells must replicate the plasmid with addition to its own DNA. adding an antibiotic gene to the plasmid gives the solution.
Most of the resistance plasmids are conjugative. In this case, E.coli are used for cloning vectors. The original genes were removed thus the plasmids do not produce antibacterial toxins. Then the antibiotic resistance gene is added which helps to identify the bacteria with altered plasmid.

Hence, the correct answer is option (A)

Note: Cloning vectors are used for cloning. The foreign DNA fragments are added into the vector. Plasmids and bacteriophage are commonly used vectors.