Question

Bacterial artificial chromosomes (BACs), cosmids, phages, plasmids and yeast artificial chromosomes (YACs) are all commonly used cloning vectors that differ in their cloning capacities, with a range from approximately 100 bp to 1000 kb. Which of the following is the increasing cloning capacity?
A. BAC, cosmid, phage, plasmid, YAC
B. YAC, BAC, cosmid, phage, plasmid
C. Plasmid, plage, cosmid, BAC, YAC
D. Plasmid, cosmid, phage, BAC, YAC

Answer 1

Hint:- A small piece of DNA that can stably maintain itself in an organism and a foreign DNA fragment can be inserted into it for cloning purposes is called a cloning vector. The examples include DNA taken from a virus, the cell of a higher organism or plasmid of a bacteria.

Complete Answer:-In general, cloning vectors are used primarily to propagate DNA. They can replicate in E. coli to form a high number of copies and contain a multiple cloning site (polylinker) with restriction sites used for inserting a DNA fragment.
The ability of a vector to clone a DNA fragment is known as the cloning efficiency of the respective vector.
The cloning capacity of various cloning vectors are as follows:-
Plasmid - 15 Kb long DNA fragments
Phage - 15- 23 Kb long DNA fragments
Cosmid - 45 Kb long DNA fragments
BAC - 300-350 Kb long DNA fragments
YAC - 1 Mb long DNA fragments
 So the correct answer is Option C.

Note:- The key features of cloning vectors are extremely necessary for their functions. These include the presence of an appropriate cloning site, the presence of Origin of Replication, selectable marker genes and restriction sites. It must not be too big in size. It should contain multiple sites for cloning and the insertion of donor DNA should not hamper with the replication process and other properties of the cloning vector. The vector and the sample DNA should both be easily digested with the same restriction enzyme as then the recombinant DNA would be enabled to grow in a host.