Question

A vector is engineered with three features which facilitates is cloning into the host cells list and explain three features

Answer 1

Answer:

A vector refers to the small piece of DNA used as vehicle which transports DNA or gene of interest into a foreign cell.

As the name suggests, the cloning vector is a type of vector which helps in maintaining the copy number of gene of interest in a cell i.e. cloning of a particular gene.

The cloning vector must have three features:

1. Origin of replication (ORI): It the sequence of DNA from where replication starts. The vector can be made to replicate in a host cell once it is attached to the ORI of that cell. It also helps in controlling the copy number of the linked DNA.
2. Selectable markers: These markers help in the screening of transformed cells from the non-tranrformants. Generally, genes coding for antibiotic resistance such as tetracycline, ampicillin, chloramphenicol etc are used as selectable markers. The transformed cells would grow easily in media containing these antibiotics whereas the non-transformants would not be able to grow in similar media.
3. Cloning site: It is the site where the gene or DNA of interest is inserted. It contains restriction site for commonly used restriction endonucleases (single site for each enzyme). It is also called as polylinker site.

Same restriction endonuclease is used to produce cut in this site and in the gene of interest to produce similar cut in both.

Few examples of cloning vectors are plasmid, cosmid, bacteriophage etc.

Answer 2

"Vectors are the DNA molecules which transport foreign DNA from test tube to host. The vectors have three important features which are given below.

• Replication : Ability to replicate

• Genetic Marker : Should differentiate between transformed and untransformed cells.

• Unique Restriction Sites : Site of unique cleavage to be present.

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