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

What are the different organ of the gastrointestinal system, The different ...

The different organs of the gastrointestinal system  Mouth or buccal cavity - Teeth 32 Permanent and - Tongue  Pharynx  Oesophagus  Stomach  Small Intestine

What is the meaning of ideometric approach, What is the meaning of Ideometr...

What is the meaning of Ideometric approach Ideometric approach in the context of neuropsychological assessment emphasises the patient's premorbid functioning with reference to

Wildlife - ecology, Wildlife - Ecology The term wildlife probably orig...

Wildlife - Ecology The term wildlife probably originated in 1913 in a book, Our Vanishing Wildlife by William Hornaday, Director of the New York Zoological Park. The main focu

Define need of vitamin c during pregnancy period, Define need of vitamin C ...

Define need of vitamin C during pregnancy period? Vitamin C deficiency has not been shown to affect the course or outcome of pregnancy in humans, although low plasma levels hav

How can we control to occur campylobacteriosis diseases, How can we control...

How can we control to occur Campylobacteriosis diseases If a person is suffering from campylobacteriosis, he can take an antibiotic such as ciproflaxin or azithromycin. Erythro

Explain the steps of exercise, Explain the Steps of Exercise You have l...

Explain the Steps of Exercise You have learnt the steps of exercises in Block 3, Unit 1 of theory block. Let us review the steps. In aerobic exercises one has to under go fo

Illustrate working of mitochondria and chloroplasts, Q. How is the finding ...

Q. How is the finding of ribosomes inside mitochondria and chloroplasts explained? It is a strong hypothesis that chloroplasts and mitochondria were prokaryotes that associated

What is protein denaturation, What is protein denaturation? Is there any ch...

What is protein denaturation? Is there any change in the primary structure when a protein is denatured? Secondary, tertiary and quaternary structures of proteins are spatial st

Which type of energy is used in photosynthesis transformed, Q. Into which t...

Q. Into which type of energy is the light used in photosynthesis transformed? The luminous energy used in the photosynthesis is transformed in to the chemical energy.

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