Manipulation of DNA - Enzymes Used In Gene Cloning скачать в хорошем качестве

Manipulation of DNA - Enzymes Used In Gene Cloning

Restriction Enzymes and DNA modification Once pure samples of DNA have been prepared, the next step in a gene cloning experiment is construction of the recombinant DNA molecule. To produce this recombinant molecule, the vector, as well as the DNA to be cloned, must be cut at specific points and then joined together in a controlled manner. As well as being cut and joined, DNA can be shortened, lengthened, copied into RNA or into new DNA molecules, and modified by the addition or removal of specific chemical groups. These manipulations, provide the foundation not only for gene cloning, but also for studies of DNA biochemistry, gene structure, and the control of gene expression. Almost all DNA manipulative techniques make use of purified enzymes. Within the cell these enzymes participate in essential processes such as DNA replication and transcription, breakdown of foreign DNA, DNA repair, and recombination between different DNA molecules. After purification from cell extracts, many of these enzymes can carry out their natural reactions under artificial conditions. Purified enzymes are therefore crucial to genetic engineering and an important industry has sprung up around their preparation, characterization, and marketing