DNA Technology

Techniques in DNA technology Restriction enzymes Gel electrophoresis PCR – polymerase chain reaction Recombinant DNA

SCI.9-12.B [Indicator] - Exemplify ways that introduce new genetic characteristics into an organism or a population by applying the principles of modern genetics.

DNA Extraction Chemical treatments Chemical treatments cause cells and nuclei to burst sticky The DNA is inherently sticky, and can be pulled out of the mixture “spooling” This is called “spooling” DNA

“Spooled” DNA

Cutting DNA Restriction enzymes Restriction enzymes cut DNA at specific sequences manageable fragments Useful to divide DNA into manageable fragments

Electrophoresis size and charge DNA can be separated based on size and charge phosphate groups negatively The phosphate groups are negatively charged gelelectricity DNA is placed in a gel and electricity is run through

Electrophoresis Negative DNA Negative DNA moves toward the positive end Smaller farther and faster Smaller fragments move farther and faster

Electrophoresis

Copying DNA Polymerase Chain Reaction Polymerase Chain Reaction Also called PCR A method of making many copies of a piece of DNA

SCI.9-12.B [Indicator] - Exemplify ways that introduce new genetic characteristics into an organism or a population by applying the principles of modern genetics.

Steps in Copying DNA A DNA molecule is placed in a small test tube DNA polymeraseDNA polymerase that can work at high temps is added

Steps in Copying DNA DNA is heated The DNA is heated to separate the two strands Primers Primers, short pieces of DNA complementary to the ends of the molecule to be copied, are added

Copying DNA DNA polymerase adds new bases to the separated strandsThe tube is cooled, and DNA polymerase adds new bases to the separated strands

PCR Large amounts of DNA can be made from a small starting sample

Genetic Engineering Genetic Engineers can alter the DNA code of living organisms. Selective Breeding Recombinant DNA PCR Gel Electrophoresis Transgenic Organisms

Selective Breeding Breed only those plants or animals with desirable traits People have been using selective breeding for 1000’s of years with farm crops and domesticated animals.

Recombinant DNA The ability to combine the DNA of one organism with the DNA of another organism. Recombinant DNA technology was first used in the 1970’s with bacteria.

Recombinant Bacteria 1. Remove bacterial DNA (plasmid). 2. Cut the Bacterial DNA with “restriction enzymes”. 3. Cut the DNA from another organism with “restriction enzymes”. 4. Combine the cut pieces of DNA together with another enzyme and insert them into bacteria. 5. Reproduce the recombinant bacteria. 6. The foreign genes will be expressed in the bacteria.

Benefits of Recombinant Bacteria 1. Bacteria can make human insulin or human growth hormone. 2. Bacteria can be engineered to “eat” oil spills.

The DNA of plants and animals can also be altered. PLANTS 1. disease-resistant and insect- resistant crops 2. Hardier fruit % of food in supermarket is genetically modified.

How to Create a Genetically Modified Plant 1.Create recombinant bacteria with desired gene. 2. Allow the bacteria to “infect" the plant cells. 3. Desired gene is inserted into plant chromosomes.

What do you think about eating genetically modified foods?

Genetically modified organisms are called transgenic organisms. TRANSGENIC ANIMALS 1. Mice – used to study human immune system 2. Chickens – more resistant to infections 3. Cows – increase milk supply and leaner meat 4. Goats, sheep and pigs – produce human proteins in their milk

Human DNA in a Goat Cell This goat contains a human gene that codes for a blood clotting agent. The blood clotting agent can be harvested in the goat’s milk.. Transgenic Goat

Desired DNA is added to an egg cell. How to Create a Transgenic Animal

PCR Polymerase chain reaction This process makes millions of copies of DNA to use in DNA fingerprinting. If a single hair is found at a crime scene, there is not enough DNA for fingerprinting. So, you take the DNA from the hair, put it into the PCR machine and you get lots of DNA to run tests on.

Gel Electrophoresis Gel electrophoresis is a commonly used method of separating molecules based on their charge, size, and shape. It is especially useful in separating charged molecules of DNA and RNA. [When an electric current is applied to the gel, negatively charged molecules move toward the positive end, and positively charged molecules move toward the negative end.] The charge, size, and shape of a particular molecule all affect the rate at which a molecule moves through the gel.

DNA Fingerprinting 1. You first must have enough DNA to run a fingerprint. PCR or polymerase chain reaction is used to make enough DNA. 2. The DNA is then cut with restriction enzymes. The more enzymes you use, the more accurate the results.

3. After the DNA is cut into small pieces, it is separated on a gel. The gel is sometimes made of agarose. The DNA is put into little holes in the gel called wells. 4. The gel is put into a electrophoresis chamber. A liquid buffer is poured over the gel and the electricity is turned on.

5. The electricity is turned on and the DNA fragments separate from each other. The largest fragments are too heavy to be carried far and the smallest fragments are carried closer to the other end. Is the other end positively or negatively charged?