DNA molecules are composed of only four nucleotides, their physical and chemical properties are very similar.

Hence, it is extremely difficult to purify individual species of DNA by classical biochemical techniques similar to those used successfully for the purification of proteins. However, we can use DNA cloning to help us to separate DNA molecules from each other.

A clone is a population of cells that arose from one original cell (the progenitor) and, in the absence of mutation, all members of a clone will be genetically identical.

DNA cloning

If a foreign gene or gene fragment is introduced into a cell and the cell then grows and divides repeatedly, many copies of the foreign gene can be produced, and the gene is then said to
have been cloned.

A DNA fragment can be cloned from any organism. The basic approach to cloning a gene is to take the genetic material from the cell of interest and introduce this DNA into bacterial cells.

Clones of bacteria are then generated, each of which contains and replicates one fragment of the genetic material.

The clones that contain the gene we are interested in are then identified and grown separately.



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