(i) Plasmid is an extra chromosomal, self-replicating, circular, double stranded DNA molecule found naturally in bacteria. (ii) ADA deficiency occurs due to the deletion of gene for adenosine deaminase enzyme. This enzyme is crucial for immune system functioning in humans.
In gene therapy, lymphocytes from the blood of the patients are grown in a culture outside the body. A functional ADA, cDNA is then introduced using a retroviral vector into the lymphocytes. These lymphocytes are then returned to the patient. Because these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes
(i) What is plasmid? (ii) What is meant by ADA deficiency? How is gene therapy a solution to this problem? Why is it not a permanent cure?
Answers
Nk yaday
(i) Plasmid is an extra chromosomal, self-replicating, circular, double stranded DNA molecule found naturally in bacteria.
(ii) ADA deficiency occurs due to the deletion of gene for adenosine deaminase enzyme. This enzyme is crucial for immune system functioning in humans.
In gene therapy, lymphocytes from the blood of the patients are grown in a culture outside the body. A functional ADA, cDNA is then introduced using a retroviral vector into the lymphocytes. These lymphocytes are then returned to the patient. Because these cells are not immortal, the patient requires periodic infusion of such genetically engineered lymphocytes