Restriction Enzyme Lab Report

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Restriction Digest Lab Write-Up Background A restriction enzyme is an enzyme that cuts DNA at specific recognition nucleotide sequences known as restriction sites. To cut DNA, all restriction enzymes make two incisions, once through each sugar-phosphate backbone or strand of the DNA double helix. Restriction enzymes can also be called scissors. These enzymes are found in bacteria and probably evolved to provide a defense mechanism against invading viruses. Inside a bacterium, the restriction enzymes selectively cut up foreign DNA in a process called restriction; while host DNA is protected by a modification enzyme. In this lab, we used a procedure known as get electrophoresis to compare how restriction enzymes cut. Purpose The purpose of this lab was to compare how different restriction enzymes cut DNA. In this lab gel electrophoresis was used. The goal of this procedure was to separate the bands by sizes. Method Uncut Lambda DNA, Pstl, EcoRI, and Hindlll have been extracted from a bacteriophage and kept on ice. The four tubes are then labeled L for uncut lambda DNA (yellow tube), P for the Pstl restriction digest of lambda DNA (violet tube), E for the EcoRI restriction digest of lambda DNA (green tube), and H for the Hindlll restriction digest of lambda DNA (orange tube). In each tube four micro liters of uncut lambda DNA, 5 micro liters of restriction buffer and one micro liter of enzyme. Only one type of enzyme was added to each tube. Enzyme was not added into the tube labeled “L”. The different micro liters had to be added to each tube in a certain order; First the DNA, then the restriction buffer, and then the enzymes. A fresh pipet tip was used each time while adding the restriction buffer and each enzyme. Each tube was then tightly capped in order to mix all reagents. The tube was then held between the index finger and thumb of one hand and

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