Drug PTC, 124 is taken orally while gene therapy requires the delivery of gene by vectors into respiratory tract. PTC 124 can be self administered while gene therapy requires proper medical treatment monitored by professionals. PTC 124 is readily taken up by cells while gene by vector system may be poorly or partially taken up by few cells.PTC 124 may have fewer or no side effects while gene therapy has possibility of side effects, i.e. viral vectors may cause infections.

It is because spores of Bacillus thuringiensis produce the insecticidal Cry proteins that are toxic when ingested by certain insects.

Very low concentration of a bacteria or virus in human body can be detected by amplification of their nucleic acid using the technique of polymerase chain reaction (PCR).This method is applied to detect HIV in suspected AIDS patients and to detect mutations in genes in suspected cancer patients.

We are aware of the facts that trade of human organs is in full swing, particularly kidneys are being sold at higher rates to organ brokers, violating a ban on such sale since 1994.Organ donation after death is rare, and most transplanted organs are coming from poor people selling them for cash.The only way out is to develop technology and create animal organs compatible with human body and make them available for transplant.In this regard, scientists have already created a human-sheep chimera which has the body of a sheep and half human organs.The time is not far away when animal organs will solve transplant problems.

Plant breeding through genetic engineering makes it possible to insert a specific gene or genes into plants. Through conventional breeding, however, it is not possible.This is because genes are usually linked, and if the desirable gene is linked with undesirable gene, it is often not possible to separate them and transfer only the desired character.Moreover, conventional breeding takes too much time and possible only in case of interspecies or intraspecies crosses.Sometimes even interspecies crosses are not possible.On the other hand, technique of genetic engineering allows to transfer genes across genera.

Hormone insulin is synthesized as a proinsulin which consists of three polypeptide chains.It undergoes a process of maturation during which the chain C consisting of 33 amino acids is removed.The mature insulin molecule consists of two short polypeptide chains of about 51 amino acids.The chain A has 21 and the chain B has 30 amino acids which are linked together by disulphide bridges.

The best possible remedial measure is gene therapy in which a defective gene is manipulated by introduction of normal healthy and functional gene/s.

Transgenic animals contain functional foreign genes introduced into their genome from another species by the technique of genetic engineering. Many of such transgenics are designed to increase understanding and study of how genes contribute to the development of disease. These laboratory exercises are specially made to serve as models for human diseases so that preventive measures and treatments for such diseases are made possible.

Golden rice is a genetically modified variety of rice. It contains 'beta carotene' genes from daffodil plant and also from some bacteria. Beta carotens is the building block of Vitamin A.Deficiency of vitamin A causes blindness.Thus, beta carotein present in golden rice can prevent blindness in children.

(i) A sheep named 'Tracy'.
(ii) Transgenic bananas that contain a portion of the 'enterotoxin' gene of E.coli.These bananas have potential to protect children against diarrhoea.
(iii) Flavr Savr tomatoes.