Cloning Vectors- Definition, Characteristics, Types, Uses


DNA is the molecule that carries the genetic information of living organisms. It consists of two strands of nucleotides that form a double helix structure. Each nucleotide has a base that can pair with another base on the opposite strand. There are four types of bases: adenine (A), thymine (T), cytosine (C), and guanine (G). A pairs with T and C pairs with G, forming the base pairs that hold the strands together.

DNA can be manipulated by using enzymes that can cut, copy, paste, or modify the nucleotides. One of the most important tools for DNA manipulation is a restriction enzyme, which can cut DNA at specific sequences. By using different restriction enzymes, DNA fragments of different sizes and shapes can be generated.

Cloning vectors are DNA molecules that can carry foreign DNA fragments into host cells, where they can be replicated and expressed. Cloning vectors are used for various purposes, such as studying gene function, producing recombinant proteins, creating transgenic organisms, or sequencing genomes.

Cloning vectors have three main features:

  • They have an origin of replication (ori), which allows them to replicate independently in the host cell.
  • They have one or more selectable markers, which confer resistance to antibiotics or other substances that can be used to identify and select the cells that contain the vector.
  • They have one or more cloning sites, which are unique restriction sites where foreign DNA fragments can be inserted.

There are different types of cloning vectors, depending on the size and source of the foreign DNA fragment, the host cell, and the desired application. Some of the most common types of cloning vectors are plasmids, bacteriophages, bacterial artificial chromosomes (BACs), yeast artificial chromosomes (YACs), and human artificial chromosomes (HACs). Each type of vector has its own advantages and limitations, which will be discussed in the following sections.