1. Biotechniques

2. Restriction Enzymes endonucleases Bacteria have endonucleases to cut up viral DNA. 400 About 400 different endonucleases Each endonuclease recognises a specific sequence of about 4-6 nucleotide bases Cut DNA into fragments at these recognition sites

3. Specific different enzymes cut the DNA at different places same enzymes always cut the DNA at the same places enzymes are named after the bacteria they are taken from

4. Protection against cutting Bacteria can protect their own DNA from restriction enzymes add methyl groups to A and C bases in sequences recognised by their own endonucleases

5. Genetic Engineer Toolkits Recognition Sites cuts isolate specific DNA fragments manipulate individual genes from any organism.

6. C T T A A A A T T CG G Sticky Ends Fragment Restriction enzyme: EcoRI C T T A A A A T T C G G C T T A A G G A A T T CG G Cut DNA with an overhang Only complementary sticky ends can join (same restriction enzyme)

7. C C C G G G C C C G G G C C C G G G C C C Blunt Ends can join to any other blunt end fragment - non-specific cut C C C G G G C C C G G G C C C G G G C C C DNA

8. Restriction enzymes http://videos.howstuffworks.com/hsw/22635-discoveries-with-bill- nye-restriction-enzymes-video.htm (restriction enzymes, 1 min) http://videos.howstuffworks.com/hsw/22635-discoveries-with-bill- nye-restriction-enzymes-video.htm http://www.dnatube.com/video/1008/Tissue-Culture (restriction enzymes, 1 min) http://www.dnatube.com/video/1008/Tissue-Culture http://www.youtube.com/watch?v=aA5fyWJh5S0 (restriction enzymes, 1 min – no sound) http://www.youtube.com/watch?v=aA5fyWJh5S0 http://www.youtube.com/watch?v=AEINuCL-5wc&feature=related (restriction enzyme, 3 min – very simple) http://www.youtube.com/watch?v=AEINuCL-5wc&feature=related http://www.youtube.com/watch?v=zF3REf7yKpw&feature=related (restriction enzymes, 7 min – students in lab, no sound??) http://www.youtube.com/watch?v=zF3REf7yKpw&feature=related