WHAT ARE RESTRICTION ENZYMES? - PowerPoint PPT Presentation

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WHAT ARE RESTRICTION ENZYMES?

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WHAT ARE RESTRICTION ENZYMES? Restriction Enyzmes molecular scissors able to cut DNA HOW DO RESTRICTION ENZYMES WORK? Usually cut DNA at a palindrome such ... – PowerPoint PPT presentation

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Title: WHAT ARE RESTRICTION ENZYMES?


1
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.

4
HOW DO RESTRICTION ENZYMES WORK?
  • - REs generate two different types of cuts
  • - Sticky ends
  • - Blunt cuts.

5
WHERE DO RES COME FROM?
  • Bacteria
  • Immune system to protect against bacteriophages
    (bacteria-infecting viruses like Lambda).

6
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
7
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.

8
WHAT ARE RES USED FOR?
  • Genetic engineering pasting together DNA from
    two different organisms.

9
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
10
HOW IS DNA PASTED TOGETHER?
  • Ligase another enzyme which reconnects
    phosphodiester bonds.

RE Video
restriction enzymes.exe
Bill Nye on Restriction Enzymes
11
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
12
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?

13
Methylation
  • See board
  • In humans, methyl groups are used to tag genes to
    turn them on or off. Stay tuned.
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