INTRODUCTION LAB 6

Intro:

Bacteria transfer genes three different ways, conjugation, transduction, or transformation. Conjugation is a process in which genetic material is passed from oned bacterium to another by **. Transduction requires a virus to carry or be the vector of the genetic material and carries the material from one bacterium to another. Transformation is the direct uptake of genetic material. Plasmids are generally taken up by the bacteria. The plasmid can carry a gene that the bacteria lacks and will help it to resist certain antibotics.

A plasmid is a small loop of DNA that can be passed on at cell division. Plasmids only have a few thousand base pairs. The genes on plasmids often give the bacteria resistance to antibotics. A bacterium that has plasmids is resistant to any attack by the antibioic-producing bacteria. Plasmids are important in genetic engineering because they can be removed from the bacteria cell. They are also readily introduced into bacterial cells that have no plasmids of their own.

The discovery of how to transfer plasmids from cell to cell was an important step in the developement of genetic engineering. A major factor in the advance of genetic engineering was the discovery of restriction enzymes. These enzymes are produced by bacteria to protect themselves from a virus.

Restriction enzymes recognizes a short sequence of DNA bases, called its target sequence. If a peice of DNA contains this sequence, the enzyme will cut the DNA at that point. This creates sticky ends where the DNA can be reconected to another DNA strand cut with the same restriction enzyme.

The process for inserting a human gene in a bacterial cell is quite simple. Restriction enzymes are used to cut up the DNA from one organism. Then the genes of interest are isolated from the fragments. Restriction enzymes are then used to open the plasmids, and the genes isolated from the first organism are inserted into those plasmids, creating recombinant DNA. This technique is called gene splicing. Then a group of bacteria is treated with the recombinant DNA. Only some take up the plasmids and transform. The bacteria are then grown on agar gel that will be there food. As the bacteria grows and divides, it makes copies with itself all carrying the plasmid. To locate your plasmid, add an antibiotic solution to your cells in which your cells of intrest to are resistant to. we are using ampicillian. The ones that survive are the ones with a plasmid for ampicillian resistance. Lastly, to identify your bacteria, add something that will make your cells of interest stand out. We used sugar and created blue and clear cells, the clear cells are the cells of interest because we placed the firefly gene in the middle of the lac gene, and so it cannot properly digest it and therefore will remain clear.

Another way to locate a gene of interest involves gene probes. Each gene is unique and has its own sequence of base pairs taht are not found in any other gene. It is a feture taht genetic engineers use to identify genes. First, they make a short strech of DNA that matches a unique part of the gene they are trying to find. This is the gene probe. The probe is labled with radioactive material. The DNA in the probe will only bind with its complimentary bases and it will be on the gene of interest. The southern blot is a common way to do this.