Download and the DNA

Chapter 13
Gene Technology
Section 1: Vocabulary Pretest
1. Length Polymorphism
2. Variable number tandem
repeats
3. Polymerase chain reaction
4. Primer
5. Restriction enzyme
6. Gel electrophoresis
7. DNA fingerprint
8. Genetic engineering
9. Recombinant DNA
10. Clone
11. Vector
12.Plasmid
13. Probe
A. Strand of RNA labeled with a
radioactive element or fluorescent dye
B. Exact copy of a DNA fragment, a whole
cell, or a complete organism
C. Enzyme that cuts DNA
D. Small rings of DNA inside bacteria cells
E. Pattern of DNA bands used for
identification
F. Process that separates DNA fragments
according to size
G. DNA from two different sources is
combined
H. Technique that quickly produces many
copies of DNA fragments
I. Small pieces of DNA needed to start
DNA replication
J. Variations in the length of a DNA
molecule between known genes
K. Repeating sequences of DNA
L. Viruses or plasmids used to carry DNA
fragments
M. Altering genetic material in order to
make new substances
Section 1 Vocab Answer Key
1. Length Polymorphism
2. Variable number tandem repeats
3. Polymerase chain reaction
4. Primer
5. Restriction enzyme
6. Gel electrophoresis
7. DNA fingerprint
8. Genetic engineering
9. Recombinant DNA
10.Clone
11.Vector
12.Plasmid
13.Probe
J
K
H
I
C
F
E
M
G
B
L
D
A
DNA Technology
• DNA Technology is the
manipulation of DNA for
practical purposes such as:
o Identification using DNA
fingerprinting
o Improving food crops
o Identifying genetic diseases
before symptoms appear
o Research for cures or
treatments of genetic
diseases
DNA Identification
• About 0.1% of human DNA
differs from person to person.
This variation allows us to:
o Identify people
o Determine paternity
o Identify human remains
o Tracing human origins
o Provide evidence in criminal
cases
Noncoding DNA
• 98% of our DNA does not code for any
protein
• It is called noncoding DNA
• It contains many length polymorphisms
(variations in the length of the DNA
molecule between known genes)
• It also contains short, repeating sequences
known as variable number tandem repeats
(VNTR)
• Geneticists use VNTR’s to determine how
rare a particular DNA profile is.
Steps in DNA Identification
1. Isolate the DNA (make
copies if needed)
2. Cut DNA into shorter
fragments that contain
known VNTR areas
3. Sort the DNA by size
4. Compare the size
fragments in the
unknown sample of
DNA to those of known
samples of DNA
Copying DNA: PCR
• Polymerase Chain Reaction (PCR) is a technique that
quickly produces many copies of a DNA fragment (it is
used if the DNA fragment is very small)
• Steps:
o Start with a fragment of DNA with the sequence to
be copied
o Heat to denature and separate the DNA strands
o Add primers (artificially made pieces of singlestranded DNA that are complementary to the ends
of the DNA fragment); DNA polymerase; and
nucleotides
o Primers will bind to original strands; DNA polymerase
will add free nucleotides to complete the strands
o Repeat about 30 times and generate millions of
copies
Cutting DNA
• Restriction Enzymes: bacterial enzymes that
recognize specific short DNA sequences and cut
them.
• Cuts are usually asymmetrical and produce “sticky
ends” so that other pieces of DNA with
complementary sequences can bind to them.
Sorting DNA by Size
• Gel Electrophoresis —technique that separates nucleic
acids or proteins according to their size and charge
• Steps:
o Cut DNA with restriction enzymes
o Place DNA into wells in a thick gel
o Run electric current through the gel
o Negatively charged DNA moves towards positive
end of the current
o Smaller fragments move faster and farther
o Transfer DNA to a nylon membrane and add
radioactive probes
o Expose x-ray film to radiolabeled membrane to
produce a DNA fingerprint
Comparing DNA
• At least 13 VNTR loci
comparisons are
needed to make a
positive DNA
identification.
• Thirteen identical loci
make the odds that
two people will share
a DNA profile about
1 in 100 billion
Recombinant DNA
• Genetic engineering —
the process of altering
the genetic material of
cells or organisms to
allow them to make
new substances. It
often involves
recombinant DNA
• Recombinant DNA —
DNA from one
organisms is added to
another
Pig expressing a jellyfish gene
Cloning Vectors
• Clone —an exact copy of a
DNA segment, a whole cell,
or a complete organism: or
to make a genetic
duplicate
• Vectors are used to clone
DNA fragments
o They carry foreign DNA
from one organism to
another
o They include
bacteriophages and
plasmids
Plasmids
• Plasmids —small rings of DNA found naturally
in bacterial cells. They replicate separately
from bacterial DNA
• Plasmids serve as
excellent vectors for
DNA
• Steps:
o Isolate the plasmid from a
bacteria cell and the DNA of
interest from a human cell (ex:
gene coding for insulin)
o Used restriction enzymes to cut
the DNA and the plasmid
o Mix the DNA and the plasmid
together; sticky ends will bond
o Use DNA ligase to join them by
forming permanent covalent
bonds
o Transfer the recombinant
plasmids back into bacterial
cells
o Allow bacteria to reproduce
(copying the plasmids to the
new cells)
o Use probes to identify the
colonies that have the desired
gene. These bacterial cells will
now be able to produce human
insulin
Probes
• A probe is a strand of RNA
or single-stranded DNA
that is labeled with a
radioactive element or
fluorescent dye and that
can base-pair to specific
DNA, such as the donor
gene in recombinant
DNA.
• Probes will glow under UV
light, allowing scientists to
identify which
recombinant colonies
have the desired gene.
Medical Applications for
DNA Technology
• Since 1982, more than 30 products made using DNA
technology are now on the market.
• Examples:
o Human insulin
o Proteins to treat immune system deficiencies and
anemia
o Clotting factors for people with hemophilia
o Human growth hormone
o Interferons for viral infections and cancer
o Growth factors for treating burns and ulcers
Section 2 Vocabulary Pretest
1. Human Genome
Project
2. Proteome
3. Single nucleotide
polymorphism
4. Bioinformatics
5. Proteomics
A.
An organism’s complete
set of proteins
B. Combines biology,
computer science and
information technology
C. The study of all of an
organism’s proteins
D. Unique spots in DNA where
individuals differ by a
single nucleotide
E. A research effort to
sequence all of the human
DNA code and locate
within it all of the
functionally important
sequences (genes)
Answer Key
1.
2.
3.
4.
5.
Human Genome Project
Proteome
Single nucleotide polymorphism
Bioinformatics
Proteomics
E
A
D
B
C
The Human Genome Project
• The Human Genome
Project began in 1990
• Its goal was to
determine the
sequence of all 3.3
billion nucleotides of
the human genome
and to map the
location of every gene
on each chromosome.
• More than 20 labs in 6
countries worked on the
project
• It was completed in
2003
DARN
What Did We Learn?
• Only 2% of our genome codes for proteins
• Chromosomes have unequal distribution of
nucleotide sequences that are transcribe and
translated
• Our genome is smaller than we thought; only about
30,000 -40,000 genes
• The same gene can encode different versions of a
protein. An organism’s complete set of proteins is
called its proteome.
• Transposons, pieces of DNA that move from one
chromosome location to another make up half of
our genome and play no role in development
• The are 8 million single nucleotide polymorphisms
(SNP). These are spots where individuals differ by
just one nucleotide.
Applications
• We have
discovered the
specific genes
responsible for
many diseases,
which can help
us to develop
treatments and
possibly cures for
the more than
4,000 human
genetic disorders
Section 3 Vocabulary Pretest
1. Gene therapy
2. Nuclear transfer
cloning
3. Telomere
4. DNA vaccine
5. Bioethics
A. Vaccine made from DNA
of a pathogen but does not
have disease-causing
capabilities
B. A method for cloning entire
organisms
C. The study of ethical issues
related to DNA technology
D. Repeated sequences of
DNA at the ends of
chromosomes
E. A technique used to treat
genetic disorders
Answer Key
1.
2.
3.
4.
5.
Gene therapy
Nuclear transfer cloning
Telomere
DNA vaccine
Bioethics
E
B
D
A
C
Genetic Engineering: Medical Applications
• Gene Therapy —a technique used to treat a
genetic disorder by introducing a gene into a
patient’s cells. It works best for disorders that result
from the loss of a single protein. Ex: Cystic Fibrosis
• Cystic Fibrosis patients lack
the CFTR gene: Result—
excess mucus in lungs
• Steps of Gene Therapy:
o Isolate the functional
gene from a healthy
person
o Insert it into a viral vector
o Infect the patient with the
recombinant virus
(carrying the functional
gene)
o The functional gene
temporarily produces the
missing protein,
improving the symptoms
of the disease
• Obstacles:
o Cells that express the
highest levels of CFTR are
deep in the lungs and
are not being reached
by the virus
o Surface cells die off
regularly so the
treatment must be
repeated often
o Immune reactions to the
treatment may occur
Genetic Engineering: Medical Applications
• Cloning —in 1996, the first clone
of an adult mammal was
developed. It was a sheep
named Dolly.
o Dolly was created by a process
known as cloning by nuclear transfer
o Steps:
• Mammary cell with its nucleus was
isolated from an adult female
sheep
• Egg cell from another sheep was
isolated and the nucleus removed
• The two cells were fused together
and an embryo developed
• Embryo was transferred into a
surrogate mother
• Dolly was born with nuclear DNA
that was identical to the donor of
the mammary cell
Professor Ian Wilmut and Dolly
Dolly suffered from premature aging and died at the age of 6. However, other cloned
animals have not experienced the same problem.
Why Clone Animals?
Most animal cloning is done
to alter the genome in some
useful way.
• Examples:
•
o Altered, cloned goats can secret
human blood clotting factors into
their milk. This can then be
extracted and used to treat
hemophiliacs.
o Cloned pigs are altered so that
their organs can be used in
human transplants with a lessened
risk of rejection.
o Altered, cloned mice are used in
the study of many human
diseases; like cystic fibrosis.
Genetic Engineering:
Medical Applications
• Vaccines —DNA vaccines are now being
researched. They are made from the DNA of the
pathogen, except the disease-causing genes are
removed.
• When injected into a patient, the patient will mount
a defense and build up antibodies.
• If the real, disease-causing pathogen then enters
the body; the antibodies will attack— preventing
illness.
• DNA vaccines to prevent AIDS, malaria and certain
cancers are currently being studied.
Genetic Engineering: Agricultural Applications
• Genetically Modified (GM)
Crops are becoming very
common. Today, most
crops can be genetically
engineered to be:
o More tolerant to
environmental conditions
o Resistant to weed killing
herbicides
o Resistant to insects and
other pests
o Resistant to diseases
o Improve nutritional value
Ethical Issues
• Bioethics —the study of ethical
issues related to DNA technology.
• Issues:
o GM crops: are they healthy for
us and are they safe for the
environment?
o Gene therapy: considered
unethical if it involves
reproductive cells that would
affect future generations
o Cloning: considered unethical
to clone human embryos for
reproduction
o Genetic make-up of individuals
should remain confidential to
reduce the possibility of
discrimination.