Biology 1A03
Lab 3: λphage DNA Analysis
Submitted: Friday, March 21, 2014
Abstract
In this experiment, the sizes of λ phage DNA were estimated after they were digested with HindIII, EcoRI, and BamHI. This study was carried out to analyze and understand the how DNA fragments of varying sizes are produced using different restriction endonucleases, and how their sizes affect separation during electrophoresis. After the incorporation with different restriction enzymes, λ phage DNA was placed into an agarose gel electrophoresis apparatus, where fragment separation occurred. The distance the DNA travelled is proportional to the length of the base pair sequence of each fragment, such that the shorter the fragment, the further along the gel it travelled. Two standard curves obtained from HindIII and 1 kb ladder experiments were used for the estimation of λ phage fragment sizes after digestion with EcoRI and BamHI restriction endonucleases. Similar methods of cutting viral DNA is used for protection in bacteria, and can also be used for the various techniques of genetic engineering (Freeman et al. 2008).
Introduction
It is known that DNA of humans and all other organisms are made up of base pair sequences which “code” for certain genes. Foreign pathogens such as lambda-phage are also made up of the same type of DNA, although their sequences or the potential sequences that lamba-phage can inject into its host, can be fatally dangerous – transmitting the E. Coli bacteria (Jeltsch, 2001). Complex organisms have developed a method of inhibit the effects of certain bacterial DNA infections from causing excessive damage, by means of restriction endonucleases (Princeton, 2014). These enzymes excise certain DNA (palindromic sequences unique to the enzyme’s recognition site), cleaving it into fragments. This is done by the hydrolysis of phosphodiester bonds, which attach complementary base pairs (Adenine and Thymine, Cytosine and...