Gene Cloning

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Lecture 10 Gene cloning
BIOLOGY Campbell, Reece and Mitchell

Chapter 20

Gene cloning technology Also known as: Genetic engineering or Genetic manipulation (GM) technology – implies precision engineering being applied to DNA molecules

Recombinant DNA technology - implies that new combinations of DNA molecules can be made I.e. “recombinant” DNA molecules

Overview of Genetic Engineering procedure 1. Making recombinant DNA molecules that can replicate in bacterial cells

Genetic engineering applications

A tool kit for recombinant DNA technology 1. Tools to cut DNA molecules into large “gene-sized” fragments 2. Vector DNA molecules that can replicate and into which “foreign” DNA can be inserted 3. Tools to join vector DNA and “foreign” DNA together to create recombinant DNA molecules 4. Methods for introducing “recombinant” DNA molecules into bacterial cells where they can replicate 5. A method for identifying bacterial cells that have taken up the recombinant DNA molecules = a method of selecting for transformants

1. Tools for cutting DNA molecules into “gene-sized” fragments Ø A typical chromosome might contain more than 5 million base pairs Ø Molecules of this enormous size cannot easily be cloned and they contain 1000’s of genes Ø A single gene might contain approximately 2,000 base pairs of DNA sequence. Molecules of this size can be easily cloned Ø For this reason, we need to be able to cut the very large chromosome-sized DNA molecules into smaller gene-sized fragments Ø This can be done using a cutting tool called a

restriction enzyme

Restriction enzymes
Ø Restriction enzymes are made by bacteria to protect themselves incoming virus DNA Ø They act as molecular scissors to cut DNA into large fragments Ø They have a unique property: they cut DNA in a sequence-specific manner by recognizing a specific sequence of bases e.g. The restriction enzyme EcoRI will only cut a DNA molecule if it contains the following sequence:...
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