Genetic EngineeringSome diabetics need to inject insulin. We used to get insulin from cows or pigs, but that took time andmoney. We now use bacteria to produce insulin because they can make it quickly and cheaply.

• How can bacteria be used to produce insulin?– We need to isolate the DNA sequence bases for human

insulin and put it into bacteria.

• How could we isolate and cut out a desired gene from DNA?

Making human insulin from bacteria:

1. Use a restriction enzyme to cut out the gene. The enzyme acts as a genetic scissors which cuts DNA at to specific sequence of nucleotides. Sticky ends are left over with nonpaired bases.

Sticky ends can form hydrogenbonds with complementary stickyend base pairs on any other DNAmolecule cut with the sameenzyme

Making human insulin from bacteria:

2. Separate insulin from the rest of the DNA by gel electrophoresis.

2. Use Polymerization Chain Reaction to make many copies of the gene

To insert the copies of the gene into the bacteria we use plasmids – circular DNA found in bacteria (not humans)

Making human insulin from bacteria:

4. Remove plasmids from bacteria and use the same restriction enzyme to cut insulin gene out of the plasmid – sticky ends are left over with nonpaired bases

5. Add broken plasmids to foreign DNA to make a recombinant DNA molecule (held together by convalent bonds formed with ligase)

6. Insert plasmid into the bacteria. When the bacteria reproduce by dividing, the human insulin gene is also reproduced, giving rise to offspring that are able to produce human insulin.

How can we use genetic engineering to get this cow to produce more milk?

Increasing milk production with rBGH

Using the same process to make insulin, use bacteria to make copies of the cow’s growth hormone.

This hormone is called rBGH (recombinant Bovine Growth Hormone)

By injecting it daily into a cow, you can increase a cow’s milk production by 10-15%.

How can we use genetic engineering to clone a sheep?

Cloning – using a cell (except an egg orsperm cell) from a multicellular organism to makeone or more genetically identicalindividuals

Dolly – the first cloned sheep!