- If all of the DNA in the nucleus is cut up with restriction enzymes and
made into plasmid recombinant DNA thousands of different fragments will be
obtained
- This is called a genomic DNA library since it contains all of the DNA from
the genome
- Bacteria will not be able to make proteins from a genomic library because
they do not know how to cut out
introns
- If proteins are required the DNA can be grown in eukaryotic cells
Messenger RNA Can be Used to Make a Complementary DNA Library
- Another way of making a DNA library is to start with messenger RNA
- The m-RNA can be converted to double strand DNA using the enzyme,
reverse transcriptase
- The DNA can then be put into plasmids to make a complementary DNA library
- This type of library shows the genes that are actually being transcribed
into m-RNA
- Bacteria can make proteins from a cDNA library because there are no
introns
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