Upload
nora-barton
View
223
Download
2
Tags:
Embed Size (px)
Citation preview
In this lesson we
• examine the use of DNA technology in forensics, medicine, and agriculture (SB2f)
Terms and topics related to DNA Technology:– Biotechnology– cloning– DNA fingerprinting– genetic engineering– Human Genome Project– plasmid– recombinant DNA
What is biotechnology?• The use of living organisms to do
practical tasks.
• Early examples:– The use of microorganisms to make
cheese and wine– Selective breeding of livestock and crops– Production of antibiotics from
microorganisms– Production of monoclonal antibodies
Goal of biotechnology today:
• To find practical applications of DNA tecniques for the improvement of human health and food production– Making gene products using Genetic Engineering
– Uses in basic research – Medical uses. Diagnosis of disease – Making vaccines and other pharmaceutical
products – Forensic uses of DNA such as DNA fingerprinting – Agricultural uses such as making transgenic plants
DNA TECHNOLOGYDNA recombination or genetic engineering is the direct manipulation of genes for practical purposes
Recombinant DNA technology
• Refers to the set of techniques for combining genes from different sources in vitro( in a test tube) and transfering this DNA into a cell so it can be expressed.
• These techniques were first developed around 1975 and resulted in the appearance of the Biotechnology industry
The tools of recombinant DNA
• Plasmids
• Restriction enzymes
• Gel electrophoresis
• PCR ( polymerase chain reaction)
– Researchers can insert desired genes into plasmids, creating recombinant DNA
• And insert those plasmids into bacteria
Bacterium
Bacterialchromosome
Plasmid
1 Plasmidisolated
3 Gene insertedinto plasmid
2 DNAisolated
Cell containing geneof interest
DNAGene ofinterest
Recombinant DNA(plasmid)
4 Plasmid put intobacterial cell
Recombinantbacterium
5 Cell multiplies withgene of interest
Copies of proteinCopies of gene
Clone of cellsGene for pestresistanceinserted intoplants
Gene used to alter bacteriafor cleaning up toxic waste
Protein used to dissolve bloodclots in heart attack therapy
Protein used tomake snow format highertemperature
Figure 12.1
Genetic Engineering
• DNA from one species is inserted into another species.
• Ex. Human Insulin for diabetics is now made by bacteria cells!
•Therapeutic hormones– In 1982, humulin, human insulin produced
by bacteria• Became the first recombinant drug
approved by the Food and Drug Administration
Figure 12.7A
Recombinant DNA
Two pieces of DNA cut with the same restriction enzyme will be able to re-combine with each other.
Plants
• 1) Examples of transgenic plants with resistance to viruses…
potatoes, tomatoes, tobacco• 2) Examples of transgenic plants with resistance
to insects… corn, cotton • 3) resistance to herbicides • 4) slow down spoilage in tomatoes • 5) Extreme example – strawberries that are resistant to drought, salt, insects, viruses, cold and frost, and improved taste
Animals
• Bacteria now produce all of the following…– Human growth hormone (HGH) – – Human insulin (replaced cow and pig insulin for
human therapy )– Follicle-stimulating hormone – Factor VIII (replaced clotting factors taken from
human blood.)
Electrophoresis• Separation of charged molecules
in an electric field.• Nucleic acids have 1 charged
phosphate (- charge) per nucleotide. Separation based (mostly) on length: longer molecules move slower.
• Done in agarose gel matrix to stabilize.
• average run: 100 Volts across a 10 cm gel, run for 2 hours.
• Stain with ethidium bromide: bonds between DNA bases and fluoresces orange.
• Run alongside standards of known sizes to get lengths
Gel electrophoresis sorts DNA molecules by size
+ +
– –
Powersource
Gel
Mixture of DNAmolecules ofdifferent sizes
Longermolecules
Shortermolecules
Completed gel
Figure 12.10
– After digestion by restriction enzymes• The fragments are run through a gel
–
+
Longerfragments
Shorterfragments
x
w
y
z
y
1 2
Figure 12.11B
Crime
• Forensic science is the use of scientific knowledge in legal situations.
• The DNA profile of each individual is highly specific.
• The chances of two people having exactly the same DNA profile is 30,000 million to 1 (except for identical twins).
•DNA and Crime Scene Investigations– Many violent crimes go unsolved
• For lack of enough evidence
– If biological fluids are left at a crime scene• DNA can be isolated from them
– DNA fingerprinting is a set of laboratory procedures
• That determines with near certainty whether two samples of DNA are from the same individual
• That has provided a powerful tool for crime scene investigators
Investigator at oneof the crime scenes(above), Narborough,England (left)
DNA Fingerprinting1st-The DNA molecule is cut with restriction enzymes
2nd- we have to separate the fragments
This is done by a technique called gel electrophoresis
The DNA is placed on a tray filled with gel through which an electric current runs causing the fragments to move through the gel. The segments separate by how far they move in the gel according to size.
The DNA will form bands corresponding to the bases (and no two people have the same sequence of bases) in the gel which are unique for each individual. This is DNA fingerprinting
Example
• A violent murder occurred.
• The forensics team retrieved a blood sample from the crime scene.
• They prepared DNA profiles of the blood sample, the victim and a suspect as follows:
Does suspect DNA bands match DNA from the crime scene?
Suspects Profile
Blood sample from crime scene
Victims profile
– DNA fingerprinting can help solve crimes
Defendant’sblood
Blood fromdefendant’s clothes Victim’s
blood
Figure 12.12A Figure 12.12B
DNA Fingerprinting
Gel Electrophoresis separates pieces of
DNA based on size (after being cut up with
restriction enzymes)Different people will
have different banding patterns.
Related individuals will have similar patterns.
Solving Medical Problems
DNA profiles can be used to determine whether a particular person is the parent of a child.
A childs paternity (father) and maternity(mother) can be determined.
This information can be used in• Paternity suits• Inheritance cases• Immigration cases
Example: A Paternity Test
• By comparing the DNA profile of a
mother and her child it is possible to
identify DNA fragments in the child
which are absent from the mother and
must therefore have been inherited
from the biological father.
29
Cloning organismsCloning organisms
• A body cellbody cell from one organism and an egg cellegg cell from another are fused
• The resulting cell divides divides like a normal embryolike a normal embryo
30
CloningCloning• CloneClone- a
member of a group of genetically identical cells
• May be produced by asexual asexual reproductionreproduction (mitosis)
What is cloning?
• Reproductive cloning– Making an exact copy of a
pre-existing or currently existing organism.
• Therapeutic cloning– Embryos are grown and
stem cells from the embryo are harvested to be used in research to develop treatment for cancer, Alzheimer’s, etc.
– Very controversial b/c it kills the embryo in the process.
Human Genome Project
• Started 1988, finished 2001, the entire sequence of bases in human DNA is now known.
• This multi-national effort has led to increased knowledge of …– Human genetic diseases– Gene therapies– Evolutionary relationships– Cellular functions– Cancer genes
Gene Libraries
• Human genes (and other genes of interest) can be stored inside bacteria cells and viruses which can be saved and grown for use in research.
• This may also preserve the genes of endangered or extinct species.