DNA TechnologyChapter 13
DNA Technology
Genetic Engineering
Uses: Cure Diseases Treat Genetic Disorders Improve Food Crops Improve Human Lives
Restriction Enzymes (R.E.)
Bacterial enzymes that cut DNA into pieces
R.E. recognizes specific nucleotide sequences
“Sticky ENDs”
Single chain “tails” of DNA that are created on each DNA segment
Sticky Ends readily bond to complementary chains of DNA
Cloning Vectors
Restriction Enzymes can isolate specific gene
Can be transferred by a cloning vector to an organism
PLASMID Small ring of DNA found in bacteria
that can serve as a cloning vector
Procedure for using cloning vectors
Restriction enzymes cut the plasmid open.
Donor gene is spliced in to the plasmidSpecific gene isolated from another organism Plasmid is returned to the bacterium The gene is replicated as the bacterium is
copiedEACH PLASMID HAS A GENE CLONE- exact copy of gene
Transplanting Genes
Plasmids transfer a gene to a bacterium so it will produce a specific protein.
EXAMPLE: INSULIN production
Large quantities are produced by inserting a human gene for insulin into a bacterium
Isolating Genes
Isolate Human DNA and Plasmid from DNA
Use Restriction Enzyme to cut DNA Splice the DNA into the plasmid to
create a GENOMIC LIBRARY
Thousands of DNA pieces from a genome that have been inserted into a cloning vector 13-4a
Producing Recombinant DNA
Recombinant DNA:
DNA from 2 or more sources
13-4c
DNA Technology Techniques
DNA Fingerprints: Pattern of bands made up of specific
fragments from an individuals DNA.
Banding patterns can be determined how closely related different organisms are.
Making a DNA FINGERPRINT
RFLP: Restriction Fragment Length Polymorphisms
1. Remove DNA and cut into fragments with restriction enzymes
2. Separate the fragments with Gel Electrophoresis
Procedure that separates nucleic acids based on size and charge.
Making a DNA Fingerprint
3. Make visible only the bands being compared. DNA fragments are blotted onto the filter paper.4. Form PROBES : Radioactive segments of DNA
complementary to the segments being compared .
Form visible bands when exposed to photographic film.
Bands can be analyzed
Accuracy of the Fingerprints
Based on how unique the prints are A complete DNA sequence is NOT
USED, only a small portion. VERY ACCURATE since they focus on
unique regions – (non-coding areas) They look for repeat patterns at 5
different sites. LESS than 1 in 1 million chance of non-
twins having the same patterns
PCR: Polymerase Chain Reaction
Procedure for making many copies of the selected segments of the available DNA
PIC
PCR: Polymerase Chain Reaction
1. A sample of DNA2. A supply of the 4 DNA Nitrogen bases
(A,T,C,G)3. DNA Polymerase (enzyme that glues
DNA)4. PRIMERS:
> Artificially made single strand of DNA required to initiate replication
PCR: Polymerase Chain Reaction
What is needed and the procedures:5. Incubation (with all ingredients)6. DNA will quickly double – Every 5 minutes7. New samples will make a DNA fingerprint8. Only need about 50 blood cells to make a sample rather than 5,000 to 50,000 for RFLP analysis.
THE Human Genome Project
THE START OF THE PROJECT: In 1990, the National Institutes of
HEALth (NIH) and the Department of ENERGY joined with international partners in a quest to sequence all 3 billion base pairs, In the human genome.
Projected to take 15 years to complete
The Human Genome Project
The Completion of the Project:
In April 2003, researchers successfully completed the Human Genome Project
Under budget and more then 2 years ahead of schedule
The Human Genome ProjectWhat have we achieved with the HGP:
Fueled the discovery of more than 1,800 disease genes
There are more than 1,000 genetic tests for human conditions
The Human Genome ProjectThe Future: Completion of the HapMap (a catalog
of common genetic variation, or haplotypes)
Genetic factors for many common diseases, such as heart disease, diabetes, and mental illness, will be found in the next few years.
A Copy of Your Personal Genome
Currently too costly ( approx $20,000 as of July 2010)
NIH will strive to cut the cost of sequencing an individual’s genome to $1,000 or less.
Having one’s complete genome sequence will make it easier to diagnose, manage, and treat many diseases.
Individualized Care based on your Genome
Powerful form of preventive, personalized, and preemptive medicine.
Tailoring recommendations to each person’s DNA, health care professionals will be able to work with individuals to focus efforts on the specific strategies
EXAMPLES: Diet and high-tech medical surveillance
Gene Therapy Technique that uses genes to treat or
prevent disease. Treat a disorder by inserting a gene into a
patient’s cells instead of using drugs or surgery.
EXAMPLES: Replacing a mutated gene that causes
disease with a healthy copy of the gene. Inactivating, or “knocking out,” a mutated
gene that is functioning improperly. Introducing a new gene into the body to help
fight a disease
Gene Therapy Successes
Nasal sprays for CF patients
Problems with Gene Therapy
Gene Therapy has had limited success It poses one of the greatest technical
challenges in modern medicine 1. Corrected gene must be delivered to
several million cells 2. Genes must be activated 3. Concern that the genes may go to the
wrong cells.4. Concern that germ cells (sex cells)
would get the genes and be passed to offspring.
Problems with Gene Therapy
5. Immune response- body will fight off the vector as a foreign invader.6. Gene gets “stitched” into a wrong space and knocks out an important gene
Patients treated for SCID’s developed Leukemia- It was found that new gene interfered with a gene that controls the rate of cell division.
What are the Ethical Issues with Gene Therapy:
Altering GERM-LINE (sex cells)
Genetic enhancement
Concerns with past practices of EUGENICS- Adolf Hitler
eu·gen·ics The study of hereditary improvement of the human race by controlled selective breeding.
Pic
Producing Pharmaceutical Products
Can be produced more inexpensively
INSULIN: produced in bulk by bacteria
Genetically Engineered Vaccines
VACCINE: Harmless version of a virus or bacterium
DNA technology may produce safer vaccines
Increasing Agricultural Yields
Can insert genes into plants to make them resistant to pests
Crops that don’t need fertilizer
Ex: Genetically enhanced tomatoes that ripen without becoming soft
Concerns with Genetically Engineered Foods
FDA requires scientific evidence that allergy- inducing properties have not been introduced into the food.
If a food contains a new protein, carbohydrate, or fat it must be approved by the FDA for sale.
Concerns that they could spread creating “SUPERWEEDS”
Examples of Super weeds
Super WeedBiotechnology. A wild plant that has been accidentally pollinated by a genetically-modified plant and now contains that plant's abilities to resist herbicides and insects
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