We have discussed restriction enzymes as a form of defense used by bacteria against viruses. Restriction enzymes are of heightened importance to today's student because of their importance as tools for recombinant DNA experiments in the molecular biology laboratory. DNA methylation is another aspect to the battle between bacteria and the phages that infect them, and methylases are often part of the same enzyme complex. DNA methylation is a process of chemical modification of DNA bases that occurs in this context as a strategy of self-recognition for the bacterium. Phages that evade restriction enzymes can possess modified bases in target sequences as well. The bacterium methylates its own DNA to prevent it from digestion, so methylated viral DNA is also protected (the methylase recognizes the same palindromic sequence as the restriction endonuclease).

The WikiPremed MCAT Course is a comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum. Please read our policies on Privacy and Shipping & Returns.  Contact Us. MCAT is a registered trademark of the Association of American Medical Colleges, which does not endorse the WikiPremed Course. WikiPremed offers the customers of our publications or our teaching services no guarantees regarding eventual performance on the MCAT.

Creative Commons License
WikiPremed is a trademark of Wisebridge Learning Systems LLC. The work of WikiPremed is published under a Creative Commons Attribution NonCommercial ShareAlike License. There are elements of work here, such as a subset of the images in the archive from WikiPedia, that originated as GNU General Public License works, so take care to follow the unique stipulations of that license in printed reproductions.