Advances in biotechnology, especially regarding genetic testing and gene therapy, now allow for the screening and possible

treatment of many genetic disorders. During gene therapy, for example, specific gene sequences are inserted into an individual's

cells and tissues to replace a defective or mutant allele.

What have scientists found to be the most efficient and effective way to insert new sequences into an individual?

A. Scientists irradiate genes so that they can be absorbed through the skin.

B.

Scientists inject DNA strands into cells using a syringe.

C. Scientists have created genetically altered foods that release DNA during digestion.

D. Scientists use viruses to insert specific gene sequences.

D. Scientists use viruses to insert specific gene sequences.

Explanation:

Gene Therapy:

Gene therapy is a treatment approach for genetic diseases that involves either the removal or the replacement of the defective gene with a normal one. Gene therapy is currently an experimental procedure that utilizes in-vivo (directly into body) and ex-vivo (taking cells outside, treating them and injecting them back into the body. Gene therapy involves the use of two kinds of vectors i. e. vehicles for carrying and injecting the normal gene into body cells: Viral vectors are modified viruses that infect the target cells and inject the normal gene in to them. Non-viral vectors mostly comprise polymers (such as lipid based particles etc.) that encapsulate the normal gene and fuse with the cell membrane of the target cells.