Question

Explain what are the desirable characteristics of an ideal cloning vector used in rDNA technology.

Answer 1

Desirable characteristics of an ideal cloning vector:

• Origin of replication: It is a specific sequence of nucleotides that serves as a binding site for initiator protein (Helicase) to start replication. Any foreign DNA linked with vector DNA also gets replicated along with it, hence it is important for maintaining the copy number of foreign DNA.
• Selectable markers: Cloning vectors must contain at least one selectable marker or it helps in:
  – detection of transformed host cells,
  – Identification and elimination of nontransformed post cells,
  – Isolation and growth of transformed host cells.
• Cloning sites: A cloning site is a restriction endonuclease recognition site or target site in vector DNA. It has a palindromic sequence of nitrogenous bases cut by a specific restriction endonuclease enzyme for insertion and linking of foreign DNA.
• Small size: A vector should be small in size because large molecules bind is break up during isolation and purification.