Restriction endonuclease enzymes occur naturally in bacteria as a chemical weapon against the invading viruses. They cut both strands of DNA when certain foreign nucleotides are introduced in the cell. Endonucleases break strands of DNA at internal positions in random manner. Types of Restriction Enzymes: 1. Restriction enzyme Type I: These enzymes interact with an unmodified recognition sequence in double-stranded [...]
Yeast episomal plasmids (YEps) are shuttle vectors. They can replicate in E. coli and also in yeast. The yeast episomal plasmids and has the following parts: 1. The 2 Micron (µm) Plasmid, 2. LEU2 Gene, and 3. The pBR 322. Part # 1. The 2 Micron (µm) Plasmid: This plasmid is found in several strains of yeast, Saccharomyces cerevisiae. It [...]
Two types of vectors are used for the introduction of foreign genes into plant cells. Among them, the Ti-plasmid of Agrobacterium tumefaciens and a few plant viruses such as caulimoviruses and geminiviruses are the most important ones. Vector # 1. Agrobacterium Tumefaciens Ti Plasmids: Plants cells do not contain natural plasmids that can be utilised as cloning vectors. However, the [...]