Restriction Enzymes

• Restriction Enzymes

  • occurs naturally in bacteria
  • function is to protect bacterial cells from infection by cutting foreign DNA into smaller pieces
  • foreign DNA = viral DNA
  • restriction enzymes cut DNA at recognition sites
  • base sequence is a palindrome (read the same backwards and forwards)
• Sticky Ends

  • leaves some nucleotides exposed
  • results in overhangs on the 2 ends of the DNA
  • sticky ends are able to bind to complementary sticky ends on other DNA
  • segments of DNA can be inserted into other segments of DNA which have been cut by the same restriction enzyme
• Blunt Ends

  • cut has occurred at the same position in each strand of the DNA
  • there are no overhanging strands
• DNA Ligase: Recombining DNA

  • an enzyme is used to join pieces of DNA
  • forms phosphodiester bonds between 2 fragments of DNA
  • recombinant DNA technology: technology that recombines DNA from different sources to modify the DNA sequence