Download Unit 6: Biotechnology

Unit 6: Biotechnology
Name __________________________________________ Hour ______
I. Mutation
A. mutation – A change in the sequence of DNA that affects the genetic information; caused by mutagens.
1. germ/sex cell mutation – _A change in the DNA/ chromosomes of a sex cell
2. somatic cell mutation – A change in the DNA/ chromosomes of a somatic cell
B. Types of Mutations
Normal Codon Sequence
1. Gene or Point Mutation – mutation that only affects one gene.
THE CAT ATE THE RAT
a) Addition or Insertion – Addition of a nucleotide or base
THE FAT CAT ATE THE
b) Subtraction or Deletion – The removal of a nucleotide
THE ATE THE RAT
c) Substitution or Missense – Bases are switched
THE COT ATE THE RAT
2. Chromosomal Mutation – Mutation that affects many genes on one or more chromosomes.
Diagrams of Chromosomal Mutations
a) Deletion – When a section of a chromosome
is removed
b) Duplication – When a section of a chromosome
is repeated
c) Inversion – When part of a chromosome becomes
oriented in reverse
d) Translocation – When a piece breaks off and
Attaches to another chromosome
e) Nondisjunction Failure of chromosomes to separate
during meiosis
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II. Selective Breeding

selective breeding – The method of improving a species by allowing only individuals with desired traits to reproduce
_____________________________________________________________________________________________

Humans have used selective breeding of dogs for thousands of years. It began as a way to have the best hunting or
retrieving dog, but today has become a hobby and competitive sport. Humans have also used selective breeding in
agriculture with plants and animals.

To maintain a desired characteristic, breeders often have to rely on inbreeding, which is the continued breeding of
dogs with similar characteristics.
? What problems may result from selective breeding and inbreeding?
- mutations
- hidden reccesiveness
- physical deformities such as blindness, and joint deformities
III. Genetic Engineering
A. Genetic Engineering – the transferring of DNA/genes from one organism to another.
1. It is also called recombinant DNA technology or gene splicing.
2. Genetic engineering can take place within a species (e.g. transferring genes between humans) or between
species (e.g. transferring genes between humans and bacteria).
? Why is it possible to transfer genes between different species and still have the gene function properly?
- matching of genetic code allows for the movement of genes
B. Steps of Genetic Engineering
1. Scientists identify the gene, a sequence of nucleotides that codes for a specific protein, that they want to
transfer. They then collect a sample of the DNA containing that gene.
2. Restriction enzymes, also known as endonucleases, are added to the sample of DNA.
a. These endonucleases naturally occur in bacteria (it is a natural defense against infection).
b. There are 100’s of known restriction enzymes, and each one identifies a specific recognition sequence of
DNA nucleotides. By trial and error, geneticists usually find a recognition sequence of DNA on either side
of the desired gene that can be cut by a restriction enzyme. Restriction enzymes get their names from the
bacteria that makes them (E. coli = Eco RI).
Examples of Restriction Enzymes and their Recognition Sequences
3. Restriction enzymes attach themselves to and cut out specific sequences of DNA nucleotides, called
recognition sequences, which are usually 4 to 6 nucleotides in length.
4. The DNA is now in fragments or pieces.
a. The ends of the DNA fragments are called “sticky” ends because when the restriction enzyme cuts the
DNA at the recognition sequence, the cut leaves two, single complementary strands that can reattach
b. Ligase – A molecule that can link together strands of DNA / RNA
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Action of Restriction Enzymes
IV. Eight Stages of Genetic Engineering
A. DNA Extraction – DNA can be removed from most cells by lysing cell membranes and separating the DNA from
other cell parts.
B. Cutting DNA – a restriction enzyme is used to cut or cleave the source DNA into fragments.
1. Each fragment is termed RFLP, which stands for Restriction Fragment Length Polymorphism
2. Because the restriction enzyme’s recognition sequence is likely to occur many times within the source DNA,
cutting will produce fragments of different lengths.
3. Different RFLPs may be made using different
that recognize different DNA sequences.
Restiction Enzymes
C. Separating DNA – the RFLPs can be separated by size using electrophoresis.
1. A mixture of DNA fragments is placed at one end of a porous gel.
2. An electric voltage is applied to the gel
____________________________
3. The negatively charged DNA molecules move toward the positive end____
4. The smaller fragments move faster through the gel and get to the positive end quicker than the larger
fragments.
Steps of Gel Electrophoresis
Well
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Example Problem:
Scientists found members of a plant species they did not recognize. They wanted to determine if the unknown species
was related to one or more of four known species, A, B, C, and D. The relationship between species can be determined
most accurately by comparing the results of gel electrophoresis of the DNA from different species. The chart below
represents the results of gel electrophoresis of the DNA from the unknown plant species and the four known species.
–
+
← Well
Band = RFLP
+
1. Which Plant Specie(s) has the smallest fragment of DNA? ______A___________________
2. Which Plant Specie(s) has the largest fragment of DNA? __Unknown, C, D_______________________
3. Which Plant Specie(s) is most closely related to the unknown plant? __C__________
4. Which Plant Specie(s) is least closely related to the unknown plant? ___B then A ________
D. Making Recombinant DNA
1. To recombine, or insert genes from one organism to another, geneticists must first cut out the desired genes
using restriction enzymes.
2. The same restriction enzymes are used to cut out a segment of DNA from a plasmid or a virus.
a. plasmid – small ring of DNA found in bacteria that has the ability to replicate but does not code for proteins
to make cellular structures or to control cellular functions.
b. virus – a nonliving structure containing a sequence of DNA that codes for its structure and function.
3. The sticky ends, which are complementary to each other, and ligase enzymes will allow the DNA fragments to
combine, creating recombinant DNA from two organisms.
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E. Cloning
1. Plasmids or viruses are then used as a vector, a genetic vehicle that carries foreign DNA into a host cell.
Usually, the host cell is a ____Bacterium___.
2. The recombinant DNA inside the host cell reproduces new cells that contain copies of the inserted gene.
F. Screening – extracting copied genes from the vector after cloning.
1. After cells are cloned, the cells are lysed (broken open to release contents) and the vector plasmids or viruses
are isolated.
2. DNA strands are split into two using heat or enzymes.
3. Radioactive probes, complementary copies of the duplicated gene, are mixed with the separated DNA strands
and form bonds with the DNA.
4. The mixture can then be separated by isolating the DNA bonded to the probes.
? Why use a radioactive probe versus a non-radioactive probe?
G. Genome Sequencing – process of locating all the genes on a chromosome of an organism and determining the
nucleotide or base sequence for each gene.
1. In DNA sequencing, a complementary DNA strand is made using a small proportion of fluorescently labeled
nucleotides. Each time a labeled nucleotide is added, it stops the process of replication, producing a short
color-coded DNA fragment. When the mixture of fragments is separated on a gel, the DNA sequence can be
read directly from the gel.
2. Several genomes have already been sequenced, including dozens of viruses and bacteria, insects (fruit fly &
Anopheles mosquito), zebra fish, fungi (yeast), plants (soybean, rice, wheat, corn, tomato), mammals (mouse,
rat, chimp, human). Several other genomes are nearing completion.
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H. Making Copies of DNA with PCR
1. Polymerase Chain Reaction – a man-made process
of producing clones of DNA sequences in a machine.
2. After sequencing the nucleotides of a desired gene,
primers are produced. A primer is a single-stranded
sequence of DNA nucleotides which is used to copy
both strands of DNA from the desired gene.
3. A solution of target DNA to be cloned and primer are
added to a PCR machine and heated to a
temperature warm enough to break the hydrogen
bonds holding the two target DNA strands together,
but not too hot to break the bonds holding the
nucleotides together (glycosidic and phosphodiester
bonds).
4. DNA polymerase and nucleotides are added to the
PCR machine which is now cooling down.
5. As the temperature continues to decrease, DNA
polymerase uses the primers as a starting point to
add free nucleotides to the strand of DNA on the
primer. When complete, the primer becomes a
lengthened complementary copy of the entire gene.
6. Because both strands are copied in PCR, there are 2
new strands of DNA for every one strand in the
solution. Amplification, or copying, continues until the
desired number of genes is made.
? How many cycles must be completed to make a million gene copies using PCR? ___21 times ________
V. Applications of Genetic Engineering
A. Reproductive Screening – Testing on healthy individuals to detect genetic disorders that may occur in offspring
__________________________________________________________________________________________
Example: amniocentesis, chorion villus sampling, fetal cell sorting, fetoscopy
B. DNA Fingerprinting – Identification of organisms using sequences of DNA that vary widely between organisms.
Example Problem:
Is Jack the father of Payle? NO
How do you know?
No markers/ fragments match up
? What are the uses of DNA Fingerprinting?
Murder, Robbery, Paternity cases, Rape
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C. Transgenics – animals or plants that possessing one or more genes from another organism
1. Transgenic Microorganisms – used to produce a variety of important substances useful for health and
industry.
2. Agrogenetics
a. Transgenic Animals – used to study genes and to improve food production and supply.
b. Transgenic Plants – used to increase the amount of food produced and increase hardiness of crops.
D. Human Genome Project – an international effort to map and sequence the human genome.
1. The project began in 1990 under the leadership of James Watson, of DNA fame, at a cost of $3,000,000,000+
dollars.
2. A draft sequence was completed in 2000, and a final sequence was announced in 2003.
? This was an international project, involving many scientists. Why is this?
1. Problem of the size of the project
2. Different ways to search for genes
3. A break through for everyone
? What are some uses for the information of the Human Genome Project?
Gene therapy and Saving a species
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E. Cloning of Dolly the Sheep and other Organisms
1. Success rate for this experiment was 1 out of 277 attempts (0.003%).
2. Steps to the cloning process:
a. Scientists extracted a donor cell from a sheep and halted its cell cycle.
b. The nucleus of an egg cell was removed.
c. The two cells (the donor and the egg) are fused together using a low current of electricity to restart the cell
cycle and division.
d. An embryo develops and is implanted into a surrogate mother.
e. The clone develops inside the womb until birth.
Process of Cloning the First Mammal
A donor cell is taken from
a sheep’s udder.
Donor
Nucleus
These two cells are fused
using an electric shock.
Fused Cell
Egg Cell
The nucleus of the
egg cell is removed.
An egg cell is
taken from an adult
female sheep.
The fused cell
begins dividing
normally.
Embryo
Cloned Lamb
The embryo
develops normally
into a lamb—Dolly
Foster Mother
The embryo is placed
in the uterus of a
foster mother.
F. Gene Therapy – a therapy used to cure a diseased individual who does not possess a copy of a necessary gene.
1. A normal gene is cut out using restriction enzymes and copied by PCR.
2. The copies are introduced into the diseased individual.
3. Methods for introducing the gene include
a. using non-harmful viruses (vector) to deliver gene to a cell’s DNA
b. intravenous (IV) injections into the bloodstream
c. direct insertion into affected cells
Gene Therapy for Sickle Cell Disease
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VI. Bioethics
A. Bioethics includes people’s response to the ever growing understanding and use of gene technologies and cell
reproduction.
B. Because of the wide variety of cultures and societies, there is a wide variety in personal ethics, causing many
bioethical beliefs and concerns. This can lead to spirited debate about biological and legal issues.
C. Examples of bioethical issues: stem cell research, genetically engineered foods, and DNA Fingerprinting.
? Who determines which technologies are carried out in a society?
Pros and Cons of Genetic Engineering
Genetic Engineering Application
Pros
Cons
Mammal Cloning
(sheep, pigs, humans)
DNA Fingerprinting
Human Genome Project
Reproductive Screening
(amniocentesis)
Agrogenetics
Gene Therapy
Stem Cell Research
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Who Controls Your DNA?
April 16. Cpl. John C. Mayfield and Cpl. Joseph Vlacovsky were found guilty of disobeying a lawful order. The U.S.
Department of Defense requires DNA samples for a database that could be used to identify soldiers’ remains. The two
Marines refused.
At their court martial, the two Marines argued that DNA samples could be examined for genes related to disease or even
behavior and, therefore, the database was an invasion of privacy. As a result of the concerns raised by this case, the U.S.
Department of Defense has changed its policies. It now destroys DNA samples upon request when an individual leaves
military service. Do people have a right to control their own DNA samples?
The Viewpoints
DNA Information Is Not Private
As the court recognized, the U.S. Department of Defense had good reasons for requiring that DNA samples be taken and
stored. Furthermore, DNA sequences are no more private and personal than fingerprints or photographs, which are taken
by private and government agencies all the time. An employer has a right to take and keep such information. Individuals
should have no reason to fear the abuse of such databases.
DNA Information Is Private and Personal
The use of DNA for personal identification by the military may be justified. An individual’s genetic information, however, is
a private matter. A recent study at Harvard and Stanford universities turned up more than 200 cases of discrimination
because of genes individuals carried or were suspected of carrying. Employers with DNA information might use it to
discriminate against workers who carry genes they suspect might cause medical or behavioral problems. Individuals must
have the right to control their own DNA and to withhold samples from such databases.
You Decide
1. What are the major issues regarding DNA databases?
2. Are there any circumstances in which an employer might be justified in demanding DNA samples from its
employees? Why might an employee wish to withhold such samples?
3. Should the control of DNA databases be a matter of law, or should it be a matter to be negotiated between
people, their employers, and insurance companies?
4. Suppose you were a doctor working as a consultant to a health insurance company. The insurance company is
trying to decide whether to test adults for cystic fibrosis alleles before agreeing to insure their families. What
advice would you give to the company about this?
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