Biotechnology & its Applications Test - 1

Adenosine deaminase enzymes is crucial for the immune system to function and its absence is caused by the deletion of a gene. It is cured by the gene therapy.
Insulin consists of chain A and chain B that are linked together by disulphide bridges.
Transgenic mice are being used to test the safety of the polio vaccine.
RNAi involves silencing of a specific mRNA due to a complementary dsRNA molecule that binds to and prevents translation of the mRNA.

The animals which carry foreign genes are called transgenic animals. The foreign genes inserted into the genome of the animal using recombinant DNA technology are called transgenes.

A human protein which is obtained from transgenic animals and is used to treat emphysema is α−1-antitrypsin. Transgenic animals that produce useful biological products can be created by the introduction of the portion of DNA which codes for particular product such as human proteins. 

Early diagnosis of disease cannot be done by transgenic animals but through techniques such as PCR and ELISA.

Dolly, the sheep, was cloned in 1997, Ian wilmur and his colleagues at the Roslin Research Scotland, took cells from ewe (mother sheep’s udder) They stored these udder cells in low nutrient culture. This stopped the starved cells from dividing switched of their active genes. One compete udder cell with its nucleus was selected, because its nucleus carries the mother's genetic information in the mean time, an unfertilised egg cell was taken from a different ewe. Its nucleus was removed leaving an empty cell containing all the essential machinery to produce an embryo. They then fused udder cell nucleus with the empty egg cell by electrical stimulation. The altered egg was cultured for six days.
Out of many resulting embryos, one was implanted in the uterus of the surrogate mother, where it grew into a lamb, So Dolly was born, genetically identical to mother sheep because her first cell nucleus came from mother’s cell. Dolly's birth proved that adult cells could acquire the cloning potential of embryonic cells.

Transgenic organism is one that has become transformed following the introduction of novel genes into its genome. It is most frequently achieved by integration of cloned DNA sequences following their injection into the fertilized egg. This fertilized egg divides mitotically to form the whole organism so that all the cells of the organism will carry the transferred gene. The transferred genes are known as transgenes.

Transgenic mice are being formed for use in testing the safety of vaccine before they are used on human beings. They are being used to test the safety of the polio vaccine. The first transgenic cow, Rosie produced human protein enriched milk (2.4 gms per litre). The milk contained the human alpha-lactalbumin. It is a more balanced product for human babies than natural cow-milk. Bulls with more power are produced by animal breeding not by genetic engineering.