12.1 Recombinant DNA technology (rDNA) – combining genes from different sources into a single molecule. The result is a transgenic organism Bacteria, like E coli, readily host recombined DNA Transgenic food crops are modified for pest resistance and increased nutrition

Plasmids – extrachromosomal DNA - of bacteria are used to customize bacteria

Restriction enzymes - a bacterial defense system - are used to ‘cut and paste’ DNA from different organisms • Each recognizes a specific DNA sequence • Many are pallindromes

complementary sticky ends • Ligase brings together the • Restriction enzymes (aka endonucleases) that produce staggered cuts are used for recombining DNA • Using the same restriction enzyme on DNA from multiple sources produces complementary sticky ends • Ligase brings together the sugars & phosphates of the two nucleic acids Plasmid DNA Foreign DNA (gene of interest) Recombinant DNA http://www.slic2.wsu.edu:82/hurlbert/micro101/images/LigaseAnimation6.gif

Find the bacteria that have taken up the rDNA plasmid Recombinant plasmid Bacterium takes up plasmid

Recombinant DNA overview

Look for the colonies that took up the target gene

12.8 –( Nucleic Acid Probes ) How to identify the clones with the gene of interest? • Use a nucleic acid probe – create the base sequence that complements the inserted gene. Tag it with florescence or radioactivity. Mix with heated DNA to get visual confirmation • If the gene of interest produces a protein, like HGH, see which clones can • pair the gene with another for antibiotic resistance; test each clone group using antibiotics

Even better: CRISPR NPR Doudna and other researchers did not pluck the molecules they use for gene editing from thin air. In fact, they stumbled across the CRISPR molecules in nature. Microbes have been using them to edit their own DNA for millions of years, and today they continue to do so all over the planet, from the bottom of the sea to the recesses of our own bodies.We’ve barely begun to understand how CRISPR works in the natural world. Microbes use it as a sophisticated immune system, allowing them to learn to recognize their More: https://www.quantamagazine.org/20150206-crispr-dna-editor-bacteria/ NPR