Genetic Engineering Toolbox

Library Screening



Description and Procedure:

Bacteria or yeast etc. containing library fragments (in plasmids) are cloned on nutrient agar. When colonies are visible a sterile filter (the size of the petri dish) is placed over them (replica plating). Some live bacteria stick to the filter from each colony. The cells on the filter are lysed; their DNA denatured forming single strands; a radioactive DNA hybridization probe is added which combines only with the target DNA. An autoradiograph is then used to locate the colony with took up the DNA fragment or gene of interest.

Uses or Function:

Used to locate a specific gene or fragment from a large gene library.