Question

In which of these vectors the size of the DNA that can be cloned is the smallest?
A. Bacterial artificial chromosome
B. Yeast artificial chromosome
C. Plasmid
D. Cosmid

Answer 1

Hint: A cloning vector is a piece of DNA which is stable and can be maintained in an organism. A foreign DNA fragment can be inserted into this vector for making clones. This cloning vector may take DNA from a virus, or it may be the plasmid of a bacterium.

Complete answer:
In this question, we have asked about the vector whose size of the DNA that can be cloned is the smallest. So first, we'll learn a little about cloning and cloning vectors. As we know, cloning is the process in which the individual is produced with identical or virtually identical DNA, either naturally or artificially. In biotechnology, cloning is making exactly the same copies of a desired DNA. A cloning vector is a piece of DNA which is stable and can be maintained in an organism. A foreign DNA fragment can be inserted into this vector and when this vector divides it will make clones. This cloning vector may take DNA from a virus, as occur in transduction or it may be the plasmid of a bacterium.
So, our 1st option is Bacterial artificial chromosome (BAC), which is an artificial DNA molecule used for cloning DNA sequences in bacterial cells (for example, E. coli). The 2nd option is Yeast artificial chromosome (YAK), which is an artificial DNA molecule used for cloning DNA sequences in yeast cells. The 3rd option is plasmid. A plasmid is a small, circular, double-stranded, extrachromosomal DNA molecule. Plasmids are used experimentally for the purposes of cloning DNA and are called vectors and the last option is cosmid. A cosmid is a hybrid plasmid which contains a sequence of Lambda phage. Cosmides are used for cloning vectors in genetic engineering and can be used to build genomic libraries. Among them, the smallest DNA Molecules can be cloned into plasmid vectors.

So, the correct option is C. Plasmid.

Note:
In plasmid, the gene can be cloned by:
> Isolation of target DNA fragments,
> Ligation of DNA fragments into a plasmid vector,
> Creating recombinant molecules,
>Transformation of recombinant plasmids into bacteria or other suitable hosts.