What is the role of Cos ends of lambda DNA?
The genome contains 48,490 base pairs of double-stranded, linear DNA, with 12-base single-strand segments at both 5′ ends. These two single-stranded segments are the “sticky ends” of what is called the cos site. The cos site circularizes the DNA in the host cytoplasm. The lambda genome can be inserted into the E.
How is bacteriophage lambda ensuring expression of its early genes?
When a decision is made to establish lysogeny, lambda ensures that the proteins that favor the lytic growth pathway disappear quickly, thereby minimizing stuttering between the lytic and lysogenic life cycle directions and ensuring that a decision is definitive.
What does bacteriophage lambda infect?
Bacteriophage lambda is a virus that infects E. coli. The typical infection cycle results in the lysis of the E. coli cell and the release of about 100 progeny phage particles, each capable of infecting another cell.
What is the role of Cos sites in bacteriophage lambda?
cos. The cos site is a ≈200 bp long segment that is required to both initiate and terminate the packaging of a monomeric genome from concatemeric DNA. The site where terminase introduces staggered nicks to generate the cohesive ends is called cosN (fig. 2).
How does bacteriophage lambda infect E coli?
The bacteriophage lambda DNA or recombinant lambda DNA-containing inserts is packaged into infectious phage particles using an efficient in vitro packaging reaction. Once the particles are formed, each one can inject its DNA into an E. coli cell.
Which vector based on bacteriophage have sticky ends?
cosmid vectors
To clone large pieces of DNA into cosmid vectors, both must have compatible sticky ends. The cosmid vector is first linearized so that each end has a cos site. Then the linear cosmid is cut with BamHI, which generates sticky ends with the overhang sequence GATC.
What is cos end?
A cosmid is a type of hybrid plasmid that contains a Lambda phage cos sequence. They are often used as a cloning vector in genetic engineering. Cosmids can be used to build genomic libraries. Cosmids can contain 37 to 52 (normally 45) kb of DNA, limits based on the normal bacteriophage packaging size.
