Genetics - Analysis and Principles

Biology

Quiz 18 :
Genetics of Viruses

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Quiz 18 :
Genetics of Viruses

Advances resulted from gene cloning are: • Gene cloning in medicines: Insulin is the important hormone in the human body which is secreted by the -cells of Islets of the Langerhans. This hormone is important for the metabolism of glucose in the body. During diseased condition when the insulin is not produced properly by the -cells, the artificially prepared insulin is injected in the body to cover up the requirement. This artificial insulin is prepared by gene cloning and is called recombinant insulin. • Gene cloning helpful in producing vaccines in the form of recombinant proteins: Vaccine against Hepatitis B virus have been produced by using this technique. The antigenic sequence of the protein coat is identified which is synthesized as a recombinant protein by the process by which synthesis of animal protein occurs. This recombinant protein is then used as a vaccine and injected into the body to prevent the occurrence of diseasE.• Gene cloning in agriculture: It was found that spraying plants with insecticides is sometimes harmful to the plant as well as it is always harmful to the environment. Then it was identified that some bacteria have insecticidal protoxin (inactive toxin) that becomes active after insertion into the insect after eating bacteria. This toxin was endotoxin and it was then used as an insect targeted insecticide and was synthesized artificially by recombinant technology i.e. gene cloning. This would not be harmful for the plant as well as to the environment.

Sticky ends in a cloning experiment are those which have complementary sequence of base pairs from different source of DNA which are capable of attachment to each other by temporary bond forming a recombinant DNA. Thus these are of importance because they are only responsible for attaching the DNA segments from different source with each other but with temporary hydrogen bonding which is made permanent by DNA ligase enzyme that converts this hydrogen bonding into covalent bonding in between the sticky ends. From above explanation it is clear that the hydrogen bonding between the ends make them sticky. The more the hydrogen bonding, more sticky will be the ends.

Ethidium bromide (EtBr) was the first fluorescent dye that was to be introduced into the chain to identify the length or amount of DNA that has been produced or we can say to detect the real time PCR. This dye on interaction with the DNA fluoresces brightly. When this dye is introduced into the tubes containing DNA, it is surrounded by hydrophobic environment created by the bases. This leads to the loss of all water molecules from the dye then it fluoresce brightly. This occurs because water molecules, that are the fluorescence quenchers, are removed out of the dye molecules and it is free to fluorescE.Nowadays new dyes have been used for this purpose like a cyanine dye called SYBR Green I is the frequently used dye as the detector in the real time PCR. Since the dye has the capability to get bound with the DNA molecules thus more the DNA molecules, more brightly it will fluoresce. Hence the fluorescence will show that more amount of PCR product is formed and thus it will show the progress of the PCR.