Question

In protoplast fusion which chemical is used?
A) DMSO
B) Liquid N2
C) Pectinase
D) PEG

Answer 1

Hint The principle of chemical transfection involves the interaction of negatively charged nucleic acids with positively charged carrier molecules, like polymers or lipids, enabling the nucleic acid to touch the negatively charged membrane components and integrating the gene into the cell by endocytosis.
Complete Step-by-step answer:
Certain chemicals (called fusogens), such as polyethene glycol (PEG), cause cell membranes to fuse together. This can be utilized to transfect animal cells by blending them with other cells having large amounts of plasmid DNA.
Schaffer first successfully used bacterial protoplasts to transfect mammalian cells in culture by treating bacterial cells with chloramphenicol to amplify the plasmid contents and lysozyme to remove the cell wall. The protoplasts were then induced to fuse with mammalian cells.
Additional information There are many chemical transfection techniques other than protoplast fusion such as transfection with calcium phosphate, transfection with DEAE-dextran, liposomes, and lipofection, receptor-mediated transfection, and physical transfection strategies are microinjection, particle bombardment, and electroporation and transduction are a virus-mediated transfection. It describes virus-mediated gene transfer. Certain animal viruses normally pass the infection to human and mammalian cells. 
Hence the correct answer is option D.
Note: Introduced DNA integrates into the host genome and is maintained permanently in the cell, this is called Stable transfection. And if the DNA introduced into the cells replicate and express without integration i.e., maintained in the nucleus is an extrachromosomal state(episomally). This is known as transient transfection.