Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
Bacteriophage Vectors
Bacteriophages are viruses that attack bacteria. Mainly phage lyses the bacterial cells they infect (lytic phages). But many others may choose to follow either lysogenic or a lytic cycle; in the second situation, the phage chromosome integrates into the bacterial chromosome and multiplies with the latter as prophage (temperate or lysogenic phages). The prophage can dissociate from the bacterial chromosome and follow the lytic cycle. Many bacteriophage are used as cloning vectors, the most generally used E. coli phages being λ (lambda) and M13 phages. Plasmid vectors have to be introduced into bacterial cells which are then cloned and choose for the recovery of recombinant vectors. In contrast, the phage vectors are sprightly tested to an suitable bacterial lawn (a constant bacterial-free zone in the bacterial lawn). Phage vectors show two advantages over plasmid vectors. (1) it is easier to screen a large number of phage plaques than bacterial colonies for the identification of recombinant vectors.(2) They are more efficient than plasmids for cloning of large DNA fragments; the largest cloned insert size in a λ vector is just over 24 kb, while that for plasmid vectors it is less than 15 kb λ Phage Vectors The λ genome (total 48,502 bp) contains an source of replication; genes for head and tail enzymes and proteins for DNA replication lysogeny and lysis; and single-stranded protruding cohesive ends of 12 bases (5' GGGCGGCGACCT; the other end is opposite to it; i.e.CCCGCCGCTGGA 5'). The λ genome remains linear in the phage head, but within E. coli cells the two cohesive ends anneal to make a circular molecule essential for replication. The sealed cohesive ends are known cos sites that are the sites of cleavage during and are essential for packaging of the mature phage DNA into phage heads. The λ DNA need to be larger than 38 kb and smaller than 52 kbto be packaged into phage particles. The genes for lysogeny are situated in the segment among 20 and 38 kb; the complete or a part of this segment is deleted to create λ vectors to (1) accommodate larger DNA inserts and (2) to ensure that the recombinant phage is always lytic.
There are 3 types of DNA sequences. Genomic DNA comes from the genome and haves both genes and extragenic material. cDNA is reverse transcribed from mRNA and corresponds only
Natural selection can therefore mean differential reproduction among members of the sarne gene pool. We earlier said that selection would promote those alleles that give rise to ph
What are the major respective constituents of cell walls in bacteria, protists, fungi and plants? Ans) In bacteria cell wall is made of peptidoglycans; between protists algae ha
what is it
In these disinfectants, iodine is incorporated along with a detergent. They are not as effective as hypochlorites against bacterial spore but also get inactivated in the pres
Is it expected that a change in the primary, in the secondary or in the tertiary structure of a protein will produce more functional consequences? Any change of the protein str
summarise the comparative anatomy of the digestive system of the invertebrate and the vertebrate.
Q. What is the relationship between environmental resistance and the population growth according to the biotic potential curve and the real population growth curve? The differe
Which organs of the body are part of the human digestive system? The digestive system, also called as "systema digestorium", or gastrointestinal system, is composed of the dige
Q. What are the two divisions of meiosis and what are the major events that occur in those divisions? Meiosis is divided into first meiotic division, or meiosis I, and second m
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd