Biotechnology and its Applications Test - 7

Alpha-1-antitrysin gene is used to treat emphysema disease. This disease causes breakdown of alveoli cell and reducing the surface area for exchange of gases.

The С peptide is not present in the mature insulin and is removed during maturation into insulin. The main challenge for production of insulin using rDNA technique was getting insulin assembled into a mature form.

In 1983, Eli Lilly an American company, first prepared two DNA sequences corresponding to A and В chains of human insulin and introduced them in plasmids of Escherichia coli to produce insulin chains. Chains A and В were produced separately, extracted and combined by creating disulfide bonds to form human insulin

Hereditary diseases are due to defects in gene. Gene can be corrected at embryonic stage by gene therapy technique in which genes are inserted into person cells or tissue to take over the function of defective gene.

Adenosine deaminase deficiency is an inherited condition that affects the immune system and typically leads to severe combined immunodeficiency (SCID). People with SCID have a reduced or absent immune response which leaves them vulnerable to frequent bacterial, viral, and fungal infections. Most people affected by ADA develop symptoms of the condition before 6 months of age.

ELISA is based on the principle of antigen-antibody interaction. Infection by pathogen can be detected by the presence of antigens or by detecting antibodies synthesized against the pathogen.

Several different tests can be used to establish whether a person is in the early stages of HIV infection . PCR viral load is the most sensitive test for detecting HIV infection in seroconversion, though greater sensitivity may be achieved when used in conjunction with the proviral DNA test.

Thequantitative polymerase chain reaction (PCR) test is performed by doing a routine blood draw. PCR amplifies genetic material (RNA) and looks for actual virus by using the reverse transcriptase (RT) enzyme to multiply HIV gene sequences in the blood sample so that they show up more easily.

A chemical reaction marks the virus and these markers are then measured and used to calculate the amount of virus in the bloodstream. This test is very reliable for detecting HIV in someone recently exposed to virus and will be highly accurate within 48 to 72 hours. An ultra-sensitive version of the RT-PCR test can detect as few as 50 copies/ml

Radioactively labeled probe can be detected by autoradiography. A single stranded DNA or RNA tagged with a radioactive molecule is allowed to hybridise to its complementary DNA in a clone of cells followed by detecting using autoradiography.

In mammals, including humans, insulin is synthesised as a prohormone (like a pro-enzyme, the pro-hormone also needs to be processed before it becomes a fully mature and functional hormone) which contains an extra stretch called the C peptide. This C peptide is not present in the mature insulin and is removed during maturation into insulin.The main challenge for production of insulin using rDNA techniques was getting insulin assembled into a mature form.

A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization.

The method is named after its inventor, the British biologist Edwin Southern. Detection of bands on a southern blot is done by probe that contain radioactive single stranded DNA or RNA.