Read the following statements.
I. Pigs are being developed for use in testing the safety of vaccines before they are used on humans.
II. Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals.
III. The first clinical gene therapy was given in 1990 to a 4-year-old girl with adenosine deaminase (ADA) deficiency.
IV. The two insulin polypeptides are connected through hydrogen bonds.
Which of the above statements are correct?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → II and III
I. Pigs are being developed for use in testing the safety of vaccines before they are used on humans. — False. The animals used to test vaccine safety are transgenic mice, for example for the polio vaccine. Pigs are among the transgenic animals produced, but the book does not name them for vaccine testing.
II. Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals. — True. This is the book’s definition. Over 95 per cent of the transgenic animals made so far are mice.
III. The first clinical gene therapy was given in 1990 to a 4-year-old girl with adenosine deaminase (ADA) deficiency. — True. ADA is an enzyme the immune system needs. The disorder is caused by deletion of the gene for ADA, and gene therapy gives the patient a working copy of the gene.
IV. The two insulin polypeptides are connected through hydrogen bonds. — False. Chains A and B of insulin are joined by disulphide bridges, not hydrogen bonds.
NCERT Extract:
Transgenic Animals – “Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals. Transgenic rats, rabbits, pigs, sheep, cows and fish have been produced, although over 95 per cent of all existing transgenic animals are mice. … (iv) Vaccine safety: Transgenic mice are being developed for use in testing the safety of vaccines before they are used on humans.”
Gene Therapy – “… The first clinical gene therapy was given in 1990 to a 4-year old girl with adenosine deaminase (ADA) deficiency.”
Genetically Engineered Insulin – “… Insulin consists of two short polypeptide chains: chain A and chain B, that are linked together by disulphide bridges (Figure 10.3).”
Figure 10.3 Maturation of pro-insulin into insulin (simplified)