21.4 Genetic engineering

• What is recombinant DNA?

  DNA molecule artificially generated from different origins (often different species)
• What is a restriction endonuclease?

  Enzyme that cuts a double stranded DNA fragment at a specific place (its restriction site)
• What is meant when a restriction enzyme recognition site is said to be 'palindromic'?

  It has the same sequence on both strands (reading from 5' to 3')
• What are 'sticky ends' in genetic engineering?

  Complementary single stranded 'overhangs' of DNA which can be used to stick two DNA fragments together.
• Do restriction enzymes catalyse condensation or hydrolysis reactions?

  Hydrolysis
• What is another method of getting the desired gene apart from using restriction endonucleases?

  Use reverse transcriptase
• What is a reverse transcriptase?

  Enzyme that makes a complementary DNA (cDNA) from the isolated mRNA made from the desired gene
• What does it mean when we say that two DNA fragments are 'annealed'?

  Joined together (compatible sticky ends)
• What process could you describe as the reverse of restriction digestion?

  DNA Ligation
• Name a common vector used in genetic engineering.

  Plasmids (also viruses, artificial chromosomes such as BACS, liposomes)
• What is the role of DNA Ligase?

  Joins DNA backbone/sugar phosphate backbone (makes phosphodiester bonds) of two DNA fragments together
• How are restriction enzymes used in genetic modification?

  Cut plasmid, isolate gene, producing sticky ends
• What is electroporation?

  Using an electrical current to make cell membranes more porous (to allow plasmids to enter)
• What is electrofusion?

  Pass tiny electric currents to the membranes of two different cells to fuse them together, forming a hybrid/polyploid cell
• What is a transgenic organism?

  One that has been genetically altered to include genetic material from another organism