Transcript MolecularBiology1APLab6

Molecular Biology Part I:
Restriction Enzymes
AP Lab 6
What you need to know!
• http://www.phschool.com/science/biol
ogy_place/labbench/lab6/intro.html
Bacteria
Contain:
• 1 chromosome
• 1 or more plasmids
• Restriction enzymes
Plasmids
• Small, circular DNA pieces
• Contain random DNA fragments that
are collected or exchanged w/ other
bacteria
• Contain nonsense information
• Sometimes contain useful information
like antibiotic resistance
Restriction Enzymes (RE)
• Enzymes that cut DNA at very specific
base sequences (often palindromes)
• Make blunt or sticky ends
• Evolved to combat invasive DNA from
viruses
• Does not cut bacterium’s DNA
because it’s missing correct DNA
sequence
• Different bacterial strains have
different RE
RE Nomenclature
• Named after the bacteria it comes
from
• First capital letter is of the genus
• Lower case letters are the species
• Next capital letter is the strain
• The number is the order of discovery
within the particular bacteria
Example: EcoRI
E = Escherichia co = coli R = RY13
EcoRI
• Cleaves double stranded
DNA at GAATTC
• Cuts between the G and A
on the top and bottom strand
G|A A T T C
C T T A A|G
• This creates a sticky end
• Other RE can create blunt
ends
– i.e.
C C|G G
G G|C C
Genetic Engineering
• RE fragments can be “glued” back
together using ligase
Biotech supply vendors offer:
• Purified RE in a large variety
• Plasmids with published restriction
maps