Biology Test 263

Retroviruses are the most important for transfection in animals. It is the process by which DNA is taken up by eukaryotic cells.

Statins are bioactive molecules which are used as blood cholesterol lowering agents. These are obtained from a yeast, Monascus perpureus.

Restriction enzymes are used to cut double-stranded DNA. These are the most important tool in genetic engineering as they have the ability to recognise and cut specific nucleotide sequences.

The first discovered restriction enzyme was Hind II. It was isolated by Smith Wilcox and Kelley in 1968. It was found that it always cuts DNA molecule at a particular point recognising a specific sequence of the six base pairs known as the recognition sequences for Hind II.

cDNA in genetic engineering is formed by reverse transcriptase. This enzyme acts by reversing transcription, i.e. it synthesises DNA from RNA template.

The genetically engineered protein which is used to treat the lung disease emphysema is -1 antitrypsin. It is an inhibitor of protease enzymes like trypsin and elastase.

More advancement in genetic engineering is due to the discovery of restriction endonucleases. These enzymes make cuts at a specific position within the DNA.

Exonucleases are the enzymes that catalyse the removal of nucleotides from the ends of DNA.

They act on single strand of DNA or gaps in double- stranded DNA. They do not cut RNA.

Biolistic gene gun is suitable for the transformation of plant cell. This extraordinary technique fires microscopic gold particles coated with the foreign DNA at the cells using a compressed air gun.

The patent granted to the Medical Centre, University of Missisippi (USA) for the use of haldi powder as a wound healing agent was challenged by CSIR, New Delhi. The patent was cancelled in 1998.