Question

Read the sources given and answer any four from the questions given below:

The gene therapy by using rDNA technology has been successfully used to cure severe combined immune deficiency (SCID) disorder. Children born with SCID, need to live in germfree conditions of plastic bubble as they cannot make adenosine deaminase (ADA) an enzyme essential for immune system. ADA deficiency is caused by the defect or deletion of a gene for enzyme ADA which is involved in the maturation of B and T lymphocytes. In the absence of these, children have a very weak immune system and tend to get lifethreatening infections even with normal cold and cough. For gene therapy, first bone marrow stem cells that produce lymphocytes are removed from the ADA-deficient patients. Then a retrovirus is used as a vector to insert a normal functional ADA gene into them. Virus inserts its nucleic acid (rDNA) including the functional ADA gene into the chromosomes of stem cells. The treated stem cells are injected back to the patient's bone marrow. As the stem cells have a functional ADA gene, they produce the ADA enzyme and the children can lead a normal healthy life.

1. The children born with SCID suffer from the following.
   1. have dysfunctional bone marrow
   2. cannot produce blood cells
   3. cannot produce B and T lymphocytes
   4. have severe anaemia
2. Which system of the body gets affected in ADA-deficient person?
   1. respiratory system
   2. immune system
   3. oxygen transport system
   4. endocrine
3. What is the role of retrovirus in treatment of SCID disorder?
   1. to strengthen immune system of body
   2. to produce antibodies
   3. to act as a vector to insert functional gene
   4. to produce B lymphocytes
4. Which cells of ADA-deficient patient are used in the gene therapy?
   1. stem cells of bone marrow
   2. erythrocytes
   3. lymphocytes
   4. antibodies
5. What is the full form of ADA?
   1. adenine deaminase
   2. adenosine deaminase
   3. adenosine deamine
   4. adenine aminase

Answer 1

1. cannot produce B and T lymphocytes
2. immune system
3. to act as a vector to insert functional gene
4. stem cells of bone marrow
5. adenosine deaminase