Final Step: Screening Gene Libraries
Library screening is done to identify the colony that has the gene of interest. If your gene library consists of thousands of colonies the search for the desired colony must obviously be directed. In most cases the screening can be done because the geneticist knows one or more details about their gene such as:
1) the protein encoded by the gene they want to clone.
2) the DNA sequence of a similar or homologous gene cloned from a different organism.
3) the gene of interest has been mapped and is known to be closely linked to DNA markers.
Understanding how the gene cloner can use the above information to identify the right colony requires you to imagine what is going on inside of the bacteria cells that make up the colonies in our gene library.
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