Restriction enzymes are enzymes produced by bacteria that cut DNA strands at specific nucleotide sequences. There are three main types of restriction enzymes: Type I cuts DNA randomly, Type II cuts every 4-6 nucleotides and is most used in biology, and Type III cuts sections up to 25 nucleotides long. Werner Arber and Stuart Linn discovered restriction enzymes, with the first being EcoB from E. coli. Restriction enzymes are used in the recombinant DNA process to cut DNA for insertion into a plasmid or virus for further study and product creation like vaccines.

1. Restriction Enzymes
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2. What Are Restriction Enzymes?
• Enzymes that are produced by different kinds
of bacteria that can cleave or cut DNA strands
at a specific sequence of nucleotides
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3. Types of Restriction Enzymes
• Type I: Random cuts occur at locations that
could be thousands of nucleotides apart
• Type III: Cuts are as long as around 25
nucleotides
• Type II: This type is most used in Biology – cuts
occur about every 4-6 nucleotides

4. Types of Cleaving
• Blunt End: Enzyme • Sticky End: Enzyme
cuts straight through cuts closer to each
side of the
recognition sequence.
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/RestrictionEnzymes.html

5. Discovery
• Werner Arber & Stuart Linn discovered
Restriction Enzymes
• 1st Restriction Enzyme that was discovered
was EcoB
– This came from a strain of E. coli
– Soon after this discovery, EcoK was discovered
from E. coli as well

6. Recombinant DNA Process
• In this process, bacterial DNA is joined with a
gene of interest
• This process is performed in order to study
the DNA more thoroughly or for useful
products like vaccines

7. Recombinant DNA Process Steps
1. DNA from the organism of interest is
prepared to be able to be cloned
2. A virus is digested with and enzyme and
compatible ends (with the DNA) are made
3. DNA in a plasmid form is cut
4. This DNA is joined with the virus’ compatible
ends
5. The DNA strands are joined with DNA ligase

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Here, the new
Compatible DNA is attached
virus ends are with DNA ligase
joined

9. Still Confused?
• The beginning of this video shows how
Restriction Enzymes work to create
Recombinant DNA:
http://www.youtube.com/watch?v=YdjvUv-1vCI

10. Sources
• http://users.rcn.com/jkimball.ma.ultranet/Bio
logyPages/R/RestrictionEnzymes.html
• http://biotech.about.com/od/proteinengineer
ing/a/restrictenz.htm
• http://www.bookrags.com/research/restrictio
n-enzymes-gen-04/