Manipulating DNA Part 1

Manipulating DNA – Old School Humans have been manipulating DNA for hundreds of years, whether they knew it or not! It all started with selective breeding which is when humans choose which organisms will create the next generation based on desirable characteristics. (Just like MENDEL!) Examples: Cows that produce - the most milk, most or highest quality meat, best hides. Corn that produces the biggest/tastiest ears.

Types of Selective Breeding Hybridization – breeding dissimilar organisms to bring together desired characteristics. Cross a plant with disease resistance and a plant with good food production. Inbreeding – breeding organisms with similar characteristics to maintain desired traits. Horse / dog / cat breeds, Mendel’s true-breeding plants. PROBLEM: brings together recessive alleles for genetic disorders (hip problems in German Shepards)

Genetic Engineering - Modern Mutations What is the original source of all genetic variability? MUTATIONS! How often do they happen? Not as often as we’d like (Evolution is VERY SLOW) How can we speed it up? By inducing mutations with radiation and chemicals. What is the result? Most mutations are harmful or inconsequential, but every once in a while we get lucky and find a beneficial mutation. How have we benefitted from this process? Bacteria that digest oil for cleaning up oil spills.

Recombinant DNA 1.The DNA (plasmid) is removed from a bacterium. 2.The gene for human growth hormone is located in a healthy human’s DNA. 3.The gene for human growth hormone is cut out of human DNA using an enzyme. 4.The plasmid is cut using the same enzyme. 5.The “sticky ends” of the two DNA fragments bond together. 6.The plasmid containing the gene for HGH is put back in the bacterium. 7.Bacterium reproduces making a bunch of bacteria that contain the human growth hormone gene.

Recombinant DNA Now the bacterium will produce human growth hormone. The HGH is then collected from the bacteria and can be injected into a patient. Example: A ten year old boy who had leukemia was undergoing chemotherapy for over a year. This is a time when children generally grow quite a bit. His illness and treatments interfered with normal growth, so he was on a regimen of human growth hormone injections to help him catch up to where he should have been.

Genetically Modified Organisms Are organisms that contain a gene from a different species.

GloFish

Remember these?

GMO’s Transgenic Microorganisms – Human genes are inserted into bacterial DNA. Products we have gotten transgenic bacteria to make: Insulin (to treat diabetes) Human Growth Hormone Clotting factors (to treat hemophilia) Using transgenic bacteria to produce these proteins is beneficial because: The products are quick and cheap to make

Transgenic Organisms Transgenic Animals We use mice with human immune systems for the purpose of studying the effects of disease without harming humans. We use livestock with extra copies of growth hormone for producing meat faster and with less fat. We use disease-resistant livestock to prevent food poisoning.

Transgenic Organisms Transgenic Plants We use plants that contain natural insecticides so that no more man-made pesticides are needed. This is beneficial for two reasons: Money-saving and better for the environment. We use plants that are resistant to weed-killing chemicals. This is beneficial to farmers because crop dusting is much less expensive than paying workers to spray individual weeds.

Part 2

Gene Therapy Procedure 1.Obtain a virus and modify its DNA so that it cannot cause disease. 2.Cut the viral DNA using an enzyme. 3.Cut out a piece of human DNA that has a working copy of the gene using the same enzyme. 4.Splice the human gene into the viral DNA. 5.Allow the virus to “infect” the person. 6.Viral DNA is transcribed and translated. 7.Person is cured! It sounds simple enough, but it doesn’t always work. Gene therapy is still very high risk and experimental. It sounds simple enough, but it doesn’t always work. Gene therapy is still very high risk and experimental.

Cloning Which sheep’s DNA is going to be used to make the clone? Sheep A Which two sheep are genetically identical? Sheep A and Lamb What is sheep C’s role in the cloning process? Surrogate (she grows the lamb in her uterus, her genetic material is not used) Which animal is the clone? Lamb

DNA Fingerprinting A DNA Fingerprint can be used to identify an individual for the purpose of maternity or paternity testing, in order to match a person to DNA found at a crime scene, or to compare species. DNA Fingerprints are created through a process called gel electrophoresis.

DNA Fingerprinting e-dna-fingerprint.html e-dna-fingerprint.html

DNA Fingerprinting 1. 1.Pour restriction enzymes into your DNA sample. The restriction enzymes will cut the DNA every time it finds a specific sequence. The restriction enzyme pictured here will cut the DNA every time it finds the sequence CTTAAG. Everyone has a different sequence, so everyone’s DNA will be cut into different length fragments.

DNA Fingerprinting 2. 2.Pour agarose gel into the tray. The gel acts as a strainer,allowing smaller pieces of DNA to move farther and faster than larger pieces Load the fragmented DNA into the wells at one end of the tray Turn the switch on. This will send an electric current through the gel creating a positively charged end and a negatively charged end. Since the DNA fragments are negatively charged they will be pulled towards the positive end of the gel. When electrophoresis is complete, the fragments will be distributed throughout the gel according to size.

DNA Fingerprinting 5. 5.Place a nylon membrane on top of the gel after it is done running.The DNA fragments will “stick” to the nylon membrane Add probes to the nylon membrane. The probes are radioactive pieces of pieces. The probes attach to the DNA fragments at certain sequences Place a sheet of X-ray film on top of the nylon membrane. The radioactivity of the probes exposes the film (just like light exposes film in a camera) Develop the X-ray film. The film displays locations on the nylon membrane where the probes attached themselves to the DNA fragments. This creates a banding pattern (much like a bar code) that is unique to each individual.