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Section 1:
DNA TECHNOLOGY-Tools of DNA
Positive ID at a crime scene
Improvement of food crops
Human predisposition for disease
Research treatments for genetic diseases
DNA Identification
No two human beings are identical genetically –
except identical twins
Human beings have pretty much the same DNA
except for 0.1%
Because of this difference, we can compare
samples of humans for paternity, providing
evidence, tracing human origins, identifying
remains
Noncoding DNA
We only use about 2% of our DNA
The remaining 98% is called noncoding DNA
This DNA contains many long, repeating varying
nucleotide sequences called variable number
tandem repeats – VNTR
CACACA CACACA CACACA CACACA CACACA
Noncoding DNA, cont.
The pattern of repeating nucleotides varies
tremendously in the human population and can
be used to make up a DNA profile
Steps in DNA
Identification
DNA Extraction (isolation)
PCR – polymerase chain reaction – the
molecular photocopying process
http://learn.genetics.utah.edu/content/labs/pcr/
Steps, cont. – RE’s
Restriction enzymes – the molecular scissors
Enzymes that can cut (hydrolyze) DNA at specific
sites.
Current DNA technology is totally dependent on
restriction enzymes.
Restriction enzymes are endonucleases – they cut
within the DNA
Steps, cont.
Bacterial enzymes – used to cut bacteriophage
DNA (viruses that invade bacteria) – why?
Different bacterial strains produce different
restriction enzymes
The names of restriction enzymes are derived
from the name of the bacterial strain they are
isolated from
Steps, cont.
Titles of restriction enzymes are derived from the first
letter of the genus + the first two letters of the
species of organism from which they were isolated.
EcoRI - from Escherichia coli
BamHI - from Bacillus amyloliquefaciens
HindIII - from Haemophilus influenzae
Steps, cont.
Steps, cont.
Using this piece of DNA, cut it with Eco RI
G/AATTC
GACCG/AATTCAGTTAATTCG/AATTC
GACCG/AATTCAGTTAATTCG/AATTC
Steps, cont.
Sticky ends – Creates an overhang. BamH1
Blunts- Enzymes that cut at precisely opposite
sites without overhangs. SmaI is an example of
an enzyme that generates blunt ends
Steps, cont. GE
Gel Electrophoresis – the molecular sieve
Separates nucleic acids or proteins based on
size and charge
DNA fingerprinting –
Banding pattern of the fragments of cut DNA on a
special gel medium (agarose)
Steps, cont. GE
http://learn.genetics.utah.edu/content/labs/gel/
Steps, cont. GE
DNA Fingerprinting
A powerful tool to analyze VNTR
Odds are 1/100,000,000,000 that any two people
will have the same genetic fingerprint!!!
Recombinant DNA
The process of altering genetic material to make
new substances – genetic engineering
The product is called recombinant DNA
Cloning Vectors
Many copies of a desired gene can be cloned and its
product harvested
This is accomplished by using a cloning vector – an
organism that contains the desired gene and can
multiply rapidly – this organism is usually a bacterium
Vector = carrier
http://www.bioteach.ubc.ca/TeachingResources/Appl
ications/GMOpkgJKloseGLampard2.swf
Probes
A strand of DNA or RNA that is radiolabeled
It is used to “fish” for the desired gene when
either carrying out recombination, or identifying
unknown DNA
Section 2: The Human
Genome
Huge research project, conducted over 13
years, sequenced and identified 20-25,000
human genes
Findings include: 2% coding DNA, RNA useful in
regulating gene expression, transposons shuffle
to make new genetic combinations
Section 3: Genetic
Engineering
Gene therapy – treat a genetic disorder by
inserting a functional gene
CFTR gene in cystic fibrosis, a temporary fix
Gene inserted into a nonpathogenic virus and
introduced into nasal spray
Not completely successful; lung tissue is deep,
cells slough off, rejection responses
Cloning
Stimulate to
divide; implant
into another
female sheep
Mammary cell
nucleus of one
sheep
Insert it into an
anucleated egg
cell from
another sheep
HELLO DOLLY!!!
Dolly died prematurely as she had short
telomeres = ends of chromosomes – like aglets!
Currently animals can be cloned to grow up
organs for human transplants
Other applications
GMOs – genetically modified organisms, crops
Increase yield, make crops weather and pest
resistant, increase nutritional value
Controversy related to genetically modified (GM)
food : risk of harm from GM food, whether GM food
should be labeled, the role of government regulators,
the effect of GM crops on the environment, the
impact of GM crops for farmers, the role of GM crops
in feeding the growing world population
GM foods, cont.
Soy, corn, dairy
Buy organic, 100% grass fed beef
Buy local
PLU codes – 5 numbers beginning with a 9 =
organic; 4 numbers = conventional; 5 numbers
beginning with an 8 = GM