DNA TechnologyDNA Technology

Techniques in DNA technologyTechniques in DNA technology

Restriction enzymesGel electrophoresisPCR – polymerase chain reactionRecombinant DNA

SCI.9-12.B-4.9 - [Indicator] - Exemplify ways that introduce new genetic characteristics into an organism or a population by applying the principles of modern genetics.

DNA ExtractionDNA Extraction

Chemical treatmentsChemical treatments cause cells and nuclei to burst

The DNA is inherently stickysticky, and can be pulled out of the mixture

This is called “spooling”“spooling” DNA

““Spooled” DNASpooled” DNA

Cutting DNACutting DNARestriction enzymesRestriction enzymes cut DNA at specific sequences

Useful to divide DNA into manageable fragmentsmanageable fragments

ElectrophoresisElectrophoresisDNA can be separated based on size and chargesize and charge

The phosphate phosphate groupsgroups are negativelynegatively charged

DNA is placed in a gelgel and electricityelectricity is run through

ElectrophoresisElectrophoresis

Negative DNANegative DNA moves toward the positive end

SmallerSmaller fragments move farther and fasterfarther and faster

ElectrophoresisElectrophoresis

Copying DNACopying DNAPolymerase Chain Polymerase Chain ReactionReaction

Also called PCR A method of making many copies of

a piece of DNA

SCI.9-12.B-4.9 - [Indicator] - Exemplify ways that introduce new genetic characteristics into an organism or a population by applying the principles of modern genetics.

Steps in Copying DNASteps 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 DNASteps in Copying DNAThe DNA is heatedDNA is heated to separate the two strands

PrimersPrimers, short pieces of DNA complementary to the ends of the molecule to be copied, are added

Copying DNACopying DNA

•The tube is cooled, and DNA DNA polymerase adds new bases to polymerase adds new bases to the separated strandsthe separated strands

PCRPCR

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

samplesample

Genetic EngineeringGenetic Engineering

Genetic Engineers can alter the DNA code of living organisms.

Selective Breeding

Recombinant DNA

PCR

Gel Electrophoresis

Transgenic Organisms

Selective BreedingSelective 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 DNARecombinant 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 BacteriaRecombinant 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 Benefits of Recombinant BacteriaBacteria

1. Bacteria can make human insulin or human growth hormone.

2. Bacteria can be engineered to “eat” oil spills.

The DNA of plants and animalsThe DNA of plants and animals can also be altered. can also be altered.

PLANTS1. disease-resistant

and insect-resistant crops

2. Hardier fruit

3. 70-75% of food in supermarket is genetically modified.

How to Create a Genetically How to Create a Genetically Modified PlantModified 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 What do you think about eating genetically modified foods?genetically modified foods?

Genetically modified organisms Genetically modified organisms are called are called transgenic organismstransgenic organisms..

TRANSGENIC ANIMALS

1. Mice – used to study human immune system2. Chickens – more resistant to infections3. 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 How to Create a Transgenic AnimalTransgenic Animal

PCRPCRPolymerase chain reactionPolymerase chain reactionThis process makes millions of copies of This process makes millions of copies of

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

Gel ElectrophoresisGel ElectrophoresisGel electrophoresis is a commonly used Gel electrophoresis is a commonly used

method of separating molecules based method of separating molecules based on their charge, size, and shape. It is on their charge, size, and shape. It is

especially useful in separating charged especially useful in separating charged molecules of DNA and RNA. [When an molecules of DNA and RNA. [When an electric current is applied to the gel, electric current is applied to the gel, negatively charged molecules movenegatively charged molecules move

toward the positive end, and positively toward the positive end, and positively charged molecules move toward the charged molecules move toward the negative end.] The charge, size, and negative end.] The charge, size, and

shape of a particular molecule all affect shape of a particular molecule all affect the rate at which a molecule moves the rate at which a molecule moves through the gel.through the gel.

DNA FingerprintingDNA Fingerprinting1.1. You first must have You first must have

enough DNA to run a enough DNA to run a fingerprint. PCR or fingerprint. PCR or polymerase chain reaction polymerase chain reaction is used to make enough is used to make enough DNA.DNA.

2.2. The DNA is then cut with The DNA is then cut with restriction enzymes. The restriction enzymes. The more enzymes you use, more enzymes you use, the more accurate the the more accurate the results.results.

3. After the DNA is cut into small 3. After the DNA is cut into small pieces, it is separated on a gel. The pieces, it is separated on a gel. The gel is sometimes made of agarose. gel is sometimes made of agarose. The DNA is put into little holes in The DNA is put into little holes in the gel called wells.the gel called wells.

4. The gel is put into a electrophoresis 4. The gel is put into a electrophoresis chamber. A liquid buffer is poured chamber. A liquid buffer is poured over the gel and the electricity is over the gel and the electricity is turned on.turned on.

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

Is the other end positively or Is the other end positively or negatively charged?negatively charged?