BIOL240 Lecture Notes - Dna Ligase, Molecular Genetics, Genomics
13 Sep 2014
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Fundamentals of microbiology (biology 140) Microbial cells often take up foreign dna from the environment, or are injected with. Some of this dna could potentially harm the cell, especially if it encodes functions that are detrimental to cellular metabolism. Many prokaryotes are able to deal with foreign dna by recognizing it as foreign and destroying it. They use what are called restriction- modification systems. The methylation prevents the restriction enzyme from cleaving at the modified sites (figure 11. 1). Restriction enzymes are very important for molecular biology and molecular genetics research. Hundreds of these enzymes, with different specificities, are available commercially (see neb website as an example). They enable the cleavage of dna molecules at specific restriction sites. Resulting restriction fragments with compatible end sequences can be ligated together (using dna ligase enzyme), resulting in recombinant dna molecules. In e. coli, the most commonly used techniques were hfr mapping and, for more precise mapping, transduction using p1 phage.
