Ingenieria Genetica

GENETIC ENGINEERING
Genetic engineering is a technology that consists of isolating, modifying and inserting genes in the same or different organism to produce proteins, the objective is to modify the traits produced by some genes to use them in a beneficial way such as gene therapy, which means to control or cure some genetic disorders. In order to do that using recombinant DNA is necessary.Recombinant DNA is a type of DNA that contains combination of DNA of different species. That DNA is cut out and inserted in a bacterial cell, yeast cell, or in a mammal cell in order to be replicated. Bacterial cell reproduce by binary fission, in one minute bacteria cell can produce thousands and millions and since it is a very fast process many copies of the DNA are replicated and can be used ingenetic research.
Restriction Enzymes
Hamilton Smith discovered that Haemophilus influenzae chops up foreign DNA inserted into it by a bacteriophage. Extracts from H. influenzae cells included an enzyme that restricts itself to a specific kind of site in DNA. It was named a restriction enzyme. In time, several hundred strains of bacteria offered up a toolkit of restriction enzymes that recognizeand cut specific sequences of four to eight bases in DNA.
Modification Enzymes
DNA fragments with staggered cuts have sticky ends. "Sticky" means a restriction fragment's single-stranded tail can base-pair with a complementary tail of any other DNA fragment or molecule cut by the same restriction enzyme. Mix DNA fragments cut by the same restriction enzyme, and the sticky ends of any twofragments having complementary base sequences will base-pair and forní a recombinant DNA molecule.


























Teacher’s comment: We are cutting the section of DNA of interest with the restriction enzyme and I also cut another piece of DNA and that piece corresponds to a plasmid, little circles of DNA contained in the bacteria. In bacteria you find a circle withDNA and next to it a plasmid where the original DNA has just one chromosome but one with many genes, the plasmid contains other genes that provide benefits in terms of adaptation, resistance. Once I cut you modify the cut DNA. You cut DNA and plasmid and unite it. The modified enzyme comes here and unites the two sticky parts DNA ligases. The mix later is fixed and we have a product calledrecombinant DNA. With a vector (plasmid + DNA) you now put it in a bacterium.
Cloning Vectorsfor Amplifying DNA
Restriction and modification enzymes make it possible to insert foreign DNA into bacterial cells. Each bacterial cell has only one chromosome, a circular DNA molecule. Many also inherit plasmids. A plasmid is a very small circle of extra DNA that has just a few genes and that gets replicatedalong with the bacterial chromosome. Bacteria usually can survive without plasmids, but some of the genes offer benefits, as when they confer resistance to antibiotics. Under favorable conditions, bacteria divide rapidly and often so that huge populations of genetically identical cells form. Before cell division, replication enzymes duplicate the bacterial chromosome and the plasmid, so a cell canhold many identical Copies of foreign DNA. A modified plasmid that accepts foreign DNA is a cloning vector. It can insert foreign DNA into a host bacterium, yeast, or some other cell that can be the start of a "cloning factory." It may give rise to a population of rapidly dividing descendant cells, all with identical [copies of the foreign DNA.




Reverse Transcriptase to Make cDNA
Mosteukaryotic genes have introns (noncoding sequences). mRNA transcripts of the genes can't be translated until the introns are snipped out and coding regions (exons) spliced together. Bacterial cells can't snip out the introns, so they often can't translate human genes into proteins. Reverse transcriptase catalyzes transcription in reverse. cDNA, a DNA strand "copied" from a mature mRNA transcript,...