1. BT 201 Biotechnology Techniques I
Restriction Enzymes
BT 201
Biotechnology Techniques I

2. What Are Restriction Enzymes?
Endonucleases produced by prokaryote organisms that are capable of cutting DNA at specific sequences
Found naturally in bacteria, used as a defense mechanism against invading nucleic acids
Exploited by molecular biologists to cut DNA to be studied or modified at will

3. How Restriction Enzymes Work
RE’s recognize a specific base sequence in the DNA, depending on what enzyme you are using
RE’s cut the DNA between the specific bases within or near that sequence, called the restriction site
The result of the cut can either be “blunt” or “sticky” ends

4. Types of Restriction Enzymes
Type I: cut 100 bases after the restriction site
Type II: cut at the restriction site
Type III: cut bases after the restriction site
The type of enzyme used depends on the desired outcome

5. Blunt Cuts Do not have an overhang
Always compatible with other blunt ends for ligation purposes
Some enzymes use this type of cut

6. Sticky Cuts Leave an overhang of bases
Sequence of material to be ligated must be complementary to overhang
Many enzymes use this type of cut

7. Where Do We Get Them?
Commercially there are several hundred RE’s available
Obtained from different species of bacteria
Named for the bacteria they come from

8. Uses of Restriction Enzymes
To cut DNA (obviously)
For determination of length of DNA extracted
For determination of presence of insert
To allow DNA to be cut and pasted
For preparation of molecular standards
To make a chromosome map

9. Disclaimer
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