Studying the genomes of organisms GENE TECHNOLOGY

Genetic Engineering- From The Beginning Cohen and Boyer isolated a gene for ribosomal RNA from the DNA of a frog and inserted it into the DNA of E.coli bacteria. During transcription the bacteria produced frog rRNA, becoming the first genetically altered organism. The process of manipulating genes for practical purposes is called genetic engineering.

Why do we use Genetic Engineering? Drugs Vaccines Improving crops Animal Farming Cloning

Why do we use Genetic Engineering? One of the first uses of this technology was for the production of human insulin. What is insulin?  A protein hormone that controls sugar metabolism. Who needs it?  Diabetics who cannot produce enough insulin. Where did they get it?  Before genetic engineering, insulin was extracted from the pancreases of slaughtered cows and pigs and then purified.  Today, the human insulin gene is cloned into bacteria so that they produce human insulin.

Words You Should Know to Understand Genetic Engineering Recombinant DNA- DNA made from two or more different organisms Restriction enzymes- enzymes that recognize and then cut the DNA between specific nucleotides. CTGAATTCCG GACTTAAGGC  CTG|AATTCCG GACTTAA|GGC  EcoR1 recognition site

Many Restriction Enzymes Exist

What do you use restriction enzymes for? Molecular Cloning

Genetic Engineering- Molecular Cloning What is molecular cloning? A set of experimental methods used to assemble recombinant DNA molecules and direct their replication in a host organism, like E. coli.

Genetic Engineering- Molecular Cloning Why do scientists use molecular cloning? To make multiple copies of a specific DNA sequence. To make large amounts of specific human proteins which can be used in medicine. To genetically modify a cell.

How does molecular cloning happen?

Step 1- Cutting DNA The DNA from the organism containing the desired gene is cut using a restriction enzyme. EX: ATTGCC TAACGG The cut produces overhanging ends, called sticky ends, which will be used to “glue” the DNA. Genetic Engineering- Molecular Cloning ATTGCC TAACGG G

Where do you “paste” the cut DNA? Vector- an agent used to carry the desired gene into another cell.  Plasmid- type of vector; circular DNA molecule found in bacteria that can replicate independently of the bacterial chromosome The vector DNA is cut with the SAME restriction enzyme.  The cut produces the SAME overhanging ends, called sticky ends, that match the organism’s DNA to the vector DNA. Genetic Engineering- Molecular Cloning

Step 1- Cutting DNA Genetic Engineering- Molecular Cloning

Step 2- Making recombinant DNA The DNA fragments from the organism are combined with the vector DNA. The fragments match up using base pairing rules. DNA ligase bonds the ends of the DNA fragments.

Genetic Engineering- Molecular Cloning Step 3- Introduction into a bacterial cell The recombinant DNA is introduced into a bacteria, such as E. coli Because bacteria reproduce by binary fission, many copies of the desired gene are made each time the host cell reproduces.

Molecular Cloning Video (click here)

Genetic Engineering Do they always use bacteria? No! Eukaryotic cells can be transformed as well, but not as simply as bacteria. Also, viruses can be modified to carry desired DNA into a eukaryotic or prokaryotic cell.

Which is better: receiving insulin extracted from pig and cow pancreases or receiving insulin produced by molecular cloning? Discuss.