Bacteriophage vectors, Biology

Assignment Help:

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.


Related Discussions:- Bacteriophage vectors

Benthos - aquatic ecosystem, Benthos - Aquatic Ecosystem The benthos o...

Benthos - Aquatic Ecosystem The benthos or the benthic organisms are those found living in or on the bottom or benthic region of the water mass. They exhibit a variety of adap

How does the cellular immune response take place, Q. How does the cellular ...

Q. How does the cellular immune response take place? The lymphocytes that participate in the cellular immune response are the T lymphocytes and T lymphocytes differentiate into

Define assessment of chromium status, Define Assessment of Chromium Status?...

Define Assessment of Chromium Status? No specific tests are currently available, which could help us to determine chromium status. Another reason being the chromium content of

Galvanotaxis - modes of cell movement, Galvanotaxis - Modes of Cell Movemen...

Galvanotaxis - Modes of Cell Movement Galvanotaxis considers to the movement of cells in response to a potential variation between cells. It is suggested that there are voltag

Respiration , why should breathe faster after a hard work

why should breathe faster after a hard work

Poo, BBBBBBBBBBBBBiiiiiiiiiiittttttttttcccccccchhhhhhhhhhhhhhh ass cunt.

BBBBBBBBBBBBBiiiiiiiiiiittttttttttcccccccchhhhhhhhhhhhhhh ass cunt.

Explain elastic fibers would not wrinkle, As we age, our skin wrinkles due ...

As we age, our skin wrinkles due to change in collagen and elastic fibers in the dermis and a decrease in their production. Explain why topical application of collagen and elastic

Physical map, Physical map is the map of locations of the identifiable lan...

Physical map is the map of locations of the identifiable landmarks on DNA (for example restriction of the enzyme cutting sites, genes), regardless of their inheritance. Distance i

Define observation or inference for fehling's test, Define Observation or I...

Define Observation or Inference for fehling's test? An insoluble reddish brown precipitate of cuprous oxide will be obtained. The reddish brown precipitate indicates the presen

Help, about how humans survive and reproduce currently. In your journal, wr...

about how humans survive and reproduce currently. In your journal, write down three adaptations that help humans have differential survivability, and three adaptations that help hu

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

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!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd