WHAT ARE RESTRICTION ENZYMES?

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WHAT ARE RESTRICTION ENZYMES?

• Restriction Enyzmes molecular scissors able to
  cut DNA

2
HOW DO RESTRICTION ENZYMES WORK?

• Usually cut DNA at a palindrome such as GAATTC.
• Palindrome word or phrase when spelled
  backwords, spells the same word or phrase
• Ex. BOB
• MADAM IM ADAM
• A Toyota! Race fast, safe car. A Toyota

5
3
GAATTC
Restriction site or Recognition Sequence

CTTAAG
3
5
3
HOW DO RESTRICTION ENZYMES WORK?

• REs cut DNAs phosphodiester bonds and hydrogen
  bonds.

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HOW DO RESTRICTION ENZYMES WORK?

• - REs generate two different types of cuts
• - Sticky ends
• - Blunt cuts.

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WHERE DO RES COME FROM?

• Bacteria
• Immune system to protect against bacteriophages
  (bacteria-infecting viruses like Lambda).

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HOW ARE RES NAMED?

• After bacteria which produces them.
• Genus
• Species
• Strain
• Order Isolated

EcoRI
HindIII
BamHI
Escherichia
Haemophilus
Bacillus
coli
influenzae
amylo.
R
d
H
I
III
I
Recognition Site
GAATTC
AAGCTT
GGATGC
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HOW DO RESTRICTION ENZYMES WORK?

• Must provide correct temperature and buffer
  (salt, pH) for enzyme to work.
• Mimics cellular conditions of bacteria they come
  from.

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WHAT ARE RES USED FOR?

• Genetic engineering pasting together DNA from
  two different organisms.

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HOW DO RESTRICTION ENZYMES WORK?

• Which are more useful in genetic engineering?
  REs that generate sticky ends or ones that
  produce blunt cuts?

STICKY ENDS
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HOW IS DNA PASTED TOGETHER?

• Ligase another enzyme which reconnects
  phosphodiester bonds.

RE Video
restriction enzymes.exe
Bill Nye on Restriction Enzymes
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WHAT ELSE ARE RES USED FOR?

• Forensics DNA Fingerprinting for crime scene
  investigation and paternity testing.
• Everyones DNA has a different sequence even
  though only 0.1 different.
• How frequently would EcoRI cut DNA?

46 once every 4096 bp
Lambda (48,514 bp) would expect about 12 EcoRI
sites
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THOUGHT QUESTION

• Bacteria are prokaryotes.
• Prokaryotes do not have a nucleus.
• Both DNA and REs are in cytoplasm.
• Why isnt bacterial DNA cut by REs?

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Methylation

• See board
• In humans, methyl groups are used to tag genes to
  turn them on or off. Stay tuned.