PURPOSE The purpose of our experiment was to determine the size of restriction fragments of lambda DNA. We did so by cutting up the DNA with different types of restriction enzymes (EcoR1, Bamh1, and Hind111) and using gel electrophoresis to separate the fragments by size. This allowed us to then analyze the projected bands using both Logger Pro and our own, hand drawn graphs. BACKGROUND DNA is a molecule that carries the the genetic material for all known living organisms. These genetic instructions are essential instructions for the growth, function, and reproduction of the organisms. Nucleotides, the monomers of DNA, are composed of one of four distinct nitrogen-containing bases—adenine, thymine, cytosine, or guanine—and …show more content…
The enzyme will recognize and cut along short, specific sequences of base pairs, called restriction sites, which are typically four to eight base pairs long. The restriction sites are palindromic, with nucleotide sequences that read the same on the forward strand as it does on the reverse strand when both are read in the same orientation. Restriction enzymes are naturally occurring in bacteria, and they aid in the protecting the bacteria from from bacteriophages viruses. Bacteriophages attack bacteria by inserting their genetic material into the cell which leads to an infection. However, some bacteria, such as E. coli, have restriction enzymes that can destroy foreign genetic material by digesting and ultimately inactivating the genes. At the same time, bacteria can also protect their own genetic material from being cut by the restriction enzymes by making slight variations to the nitrogen bases in its genome. Since restriction enzymes need specific restriction sites in order to make an incision, without the correct order of nucleotides the enzyme cannot do its job. This prevents the restriction enzymes from cutting and digesting DNA sequences from the bacteria