While cloning vectors, which of the two will be preferred by biotechnologists -
bacteriophages or plasmids. Justify with reason.

Dear Student,

Vector can be defined as a vehicle which can carry a DNA molecule of interest to the host organism. 
The features which are required in a vector include:
1) Capable of replicating in host
2) Relatively small molecular weight
3) Availability of selectable markers
4) Contain multiple cloning sites (MCS)
5) Multiple copies of vector

Now, Plasmids - These are extrachromosomal, double stranded, covalently closed circular (super coiled) DNA molecules. Found in wide variety of bacteria and vary in sizes from 1 Kb to 200 Kb. They can carry up to 15 Kb of foreign DNA (like plasmid pBR322). 
These are generally used for cloning vectors for the study of prokaryotic transcription and translation. Improved versions like pUC can also be used for cloning efficiently due to presence of more restriction sites and for blue-white screening.

Bacteriophages are viruses which infect bacteria. They are not used as vectors rather these kinds of vectors are called as Phagemids. It is derived from bacteriophage lambda. This DNA is linear, double stranded and has 12 nucleotides overhangs known as cos sites (on both 5' ends of the DNA and are complementary in nature). Upon entering in to the host these the dsDNA gets circularised due to cos sites. 
Uses/Importance: Contain useful restriction sites for cloning
2. Allow cloning of DNA molecule of a broad range
3. Useful in differentiation of parent and new cells by markers and plague formation
4. Biologically safe.
5. It can accommodate a maximum of 24.6 Kb (sometimes 38-52 Kb) foreign DNA molecule for cloning purposes.

Therefore, depending upon the size and host one can select the vector to be used. Both of these vectors are suitable for their respective functions for various purposes.

Hope this information will clear your doubts about the topic.

If you have any more doubts just ask here on the forum and our experts will try to help you out as soon as possible.



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