4.4 Genetic Engineering and Biotechnology - HS Biology IB


14 déc. 2012 (il y a 8 années et 7 mois)

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This pedigree shows a genetic condition in a family. It is not sex linked,
figure out if it is dominant or recessive. Why?




On your first day interning in the office of a human geneticist, a man with purple ears
walks in. You questioned the man and wrote down the following family history

The man's mother and one of his sisters also had purple ears, but his father, his
brother, and two other sisters had normal ears. The man and his normal
eared wife
had seven children, including four boys and three girls. Two girls and two boys had
purple ears.

Draw the family pedigree and indicate what form of inheritance that the purple
trait most likely follows.

What are the genotypes of his parents?

Pedigree Word Problem

4.4 Genetic Engineering and Biotechnology

Outline the use of the polymerase chain reaction (PCR) to copy and amplify minute
quantities of DNA

State that, in gel electrophoresis of DNA, fragments of DNA move in an electric field and
are separated according to their sizes.

State that gel electrophoresis of DNA is used in DNA profiling.

Describe the application of DNA profiling to determine paternity and also forensic

Outline 3 outcomes of the sequencing of the complete human genome.

State that, when genes are transferred between species, the amino acid sequence of the
polypeptides translated from them is unchanged because the genetic code is universal.

Outline a basic technique used for gene transfer involving plasmids, a host cell (bacterium,
yeast or other cells), restriction enzymes and DNA

Assessment Statements

State two examples of the current uses of genetically modified crops or animals.

Discuss the potential benefits and possible harmful effects of one example of
genetic modification.

Define clone

Outline a technique for cloning using differentiated animal cells.

Discuss the ethical issues of therapeutic cloning in humans.

Assessment Statements continued…..

Answer the following

What is biotechnology?

How has biotechnology and genetic engineering helped society? Give

What ethical issues are raised with these advancements?

What is DNA profiling? What can be found at a crime scene that can be used
to get DNA?

What is polymerase chain reaction (PCR)?

What is gel electrophoresis? Describe the technique.

What are restriction enzymes?

What is the human genome project? When did it start? Completed?


Genetic engineering and biotechnology have opened new
opportunities in forensic science, agriculture, medicine and food

As knowledge has grown, science has enabled us to manipulate the unique
genetic identity of organisms.

Gene transfer, cloning and stem cell research have raised questions and the
safety and ethics of techniques that are new to this generation.

DNA Profiling

At crime scenes, forensic scientists check for fingerprints because
fingerprints are unique can be used to identify someone.

Forensic scientists also collect samples of hair, skin, blood and other body
fluids that contain a person’s DNA.

Fingerprint Types

DNA Profiling

Matching the DNA from a sample to a known individual is called
DNA profiling

Along with forensic science DNA profiling can be used to determine





(No need to know)

The ELISA has been used as a diagnostic tool in medicine as well as a quality

check in
various industries.

In simple terms, in ELISA, an unknown amount of antigen is affixed to a surface, and then a
specific antibody is applied over the surface so that it can bind to the antigen.

This antibody is linked to an enzyme, and, in the final step, a substance containing the enzyme's

is added. The subsequent reaction produces a detectable signal, most commonly a
color change in the substrate.


(No need to know)



(LAL) is an aqueous extract of blood cells

from the horseshoe crab.

An extract of the horseshoe crab's blood is used by the pharmaceutical
and medical device industries to ensure that their products, intravenous
drugs, vaccines, and medical devices, are free of bacterial contamination. No
other test works as easily or reliably for this purpose.

Gel Electrophoresis

Gel electrophoresis is a method used to separate fragments of DNA
on the basis of size and the electrical charge they carry.

It can indentify natural variations found in every individual’s DNA.

Any DNA sample usually contains long
molecules that are too large to be used for

Enzymes, called
restriction enzymes
used to cut DNA into fragments at very
precise points in the base sequences.

Since each person has a unique DNA
sequence, the position of these cutting sites
will vary, resulting in different fragment sizes.

The DNA fragments are placed in a well in a plate of a gel and an electrical field is applied.

Each DNA fragment has a small negative charge so will move in the electrical field, through
the gel.

The distance a fragment can move depends on its size: smaller fragments move more easily
through the gel matrix and travel further, while larger fragments are left behind close to their

After fragments have separated in the gel, they are stained and produce a unique pattern of
bands called a
DNA profile.

Mr. Conte

Mr. Brown


Run a gel yourself!!


Polymerase Chain Reaction (PCR)

DNA profiles can only be done if there is sufficient DNA to
complete the procedure.

Sometimes at a crime scene or when a body is found after a long
period of time, only a minute amount can be collected.

PCR is a simple method that makes millions of copies of a tiny
amount of DNA.

At high temperatures a special type of DNA polymerase enzyme is used
to build up two new complete copies of the DNA.

By cycling through lowering and raising temperatures it amplifies the
process creating many strands of DNA.


Thoughts to Consider

DNA profiles do not show individual base sequences but only
identify repeated sequences. How much confidence should be
placed on DNA evidence?

What are the implications for society if the authorities were to
hold a DNA profile for every person?

What safeguards should be in place to protect the rights of
individuals whose DNA profiles have been placed on a database
but have not been convicted of a crime?

Is it right to convict a person on DNA evidence alone?

The Human Genome Project

In 1990, the Human Genome Project was started as an international
collaboration to determine the entire base sequence of the human genome.

The sequencing of three billion base pairs was completed in 2003.

Work continues on locating genes and mapping specific positions on

Identifying and studying the proteins produced by these genes may soon give a
better understanding of genetic disorders.

Since 2003, other genome
sequencing projects have been undertaken to
gather data on populations from different parts of the world and analyze
genetic variation.

Just knowing the base sequence of a chromosome does not have much
scientific value, however, knowing the sequence of the genes on that
chromosome is a great value to molecular medicine, forensic science and
studying evolution.

Medical Benefits

Improved diagnosis of diseases

finding faulty genes allows for early diagnosis
and earlier or preventative treatment

Earlier detection of genetic susceptibility to a disease

Better identification of carriers of genetic conditions

Gene therapy, which aims to repair or replace a faulty gene

Drug design to find new classes of drugs that act on specific genes

, where the drug is tailored specifically to an individual

Gene Technology

Gene technology
, also known as genetic modification (GM) or
involves the transfer of genes from one species to another in
order to produce new varieties of organisms with useful or desirable

Selective plant and animal breeding has been carried out by humans for
thousands of years as people tried to develop cattle that produced more milk
or crops with better resistance to diseases.

Animals or plants of the same species were chosen for breeding because of a
certain trait. Over many generations of selection, the desired trait increase in
frequency in the population.

Gene technology gives us the ability to transfer genes from one species to
another completely different species in just one generation.


Bacterial genes have been transferred to plants, human genes to bacteria
(insulin) and spider genes transferred to a goat.

Glow in the dark monkeys and cats

Could help with AIDS


Gene transfer is possible because the genetic code is universal.

No matter what the species, the genetic code spells out the same
information and produces an amino acid sequence that is exactly the
same in any species.

Technique of Gene Transfer

Insulin was the first gene transfer that was used for medical purposes.

Before diabetics used insulin from cow or pig pancreases.

Today diabetics inject themselves with human insulin that has been made by
modified E. coli.

3 Key Steps:

Obtaining the desired human insulin gene in the form of a piece of DNA

Attaching this DNA to a vector, which will carry it into the host cell
) the vector used is the plasmid found inside the bacterium.


bacteria so that they translate the DNA and make

Plasmids from bacteria are cut with restriction enzymes (scissors) to produce sticky

Cells from the human pancreas are extracted, the mRNA code for the human insulin
gene are isolated, DNA polymerase builds the DNA and it’s cut with the same
restriction enzymes.

The insulin DNA and the plasmid DNA are mixed together, with a

enzyme. The
sticky ends are joined by the

(like glue).

The recombinant plasmid with the insulin gene is introduced into bacteria.

The gene is cloned by growing the bacteria.


Genetically Modified Organisms (GMOs)

There are over 100 plant species that have been genetically

Most genetic engineering has involved commercial crops such as
corn, potatoes, tomatoes and cotton.

Plants have been modified to make them resistant to pests, disease
and tolerant to herbicides.

Salmon have been modified to grow larger and mature faster

Herbicide Tolerance

Herbicides are used to kill weeds in crop fields but they are expensive
and can affect local ecosystems as well as cultivated areas.

One very common and powerful herbicide is
, which is
broken down by soil bacteria.

Farmers used to have to spray this herbicide several times a year, but
now the gene has been transferred into corn making them

to the herbicide.

Farmers can plant the modified corn seeds, which grow along with the
competing weeds.

Spraying once with

kills the weeds and leaves the corn

The corn then grows and out
competes any weeds that grow later.

Crop yields are improved and less herbicide has to be used.

If you could save lives by producing vaccines in transgenic bananas, would you?

Debate about GMOs

Impact on other species/ biodiversity


Philosophy/ Religious concerns

Population increases, climate change

Benefits of GMO’s

As our population increases and more people need feeding, modifying plants and
animals to increase yield or to be able to grow plants in places where they
previously could not, will provide more food. Plants can be made more tolerant
to drought or salt water so that food can be grown in difficult areas.

Crop plants that are disease resistant not only increases yields but also reduce
the need for applying potentially harmful pesticides.

Many substances, such as human growth hormone, a blood
clotting factor,
antibodies, and vitamins, are already being made by GMO’s to improve human

Harm from GMO’s

Animals could be harmed by having genes inserted in them.

There is concern that people consuming genetically modified
plants and animals could be harmed.

The long term effects of genetically modified crops in the
environment are unknown. Plants or animals could escape into
the environment and their genes might become incorporated
into wild populations, with unknown effects.

Human food crops could become controlled by a small number
of biotech companies.

GM seeds/plants may be more expensive, preventing poorer
farmers from buying them. Wealth might become concentrated in
smaller percentage of the population, which may damage the local

More GMO’s may lead to a reduction in natural biodiversity.

Reducing Pollution

Pigs fed on grains and soybeans produce a lot of phosphate in their manure.

Phosphate causes pollution and algal blooms in the environment.

Genetically modified pigs have developed with a gene from E. coli.

The bacteria make an enzyme which releases the digestible phosphorus found in grains
and soybeans.

Genetically modified pigs produce the enzyme in their saliva and digest the food better.

More phosphorus become available to them, so the pigs absorb the nutrients so they
grow better and much less phosphate is released in the manure.


a group of genetically identical organisms or group of cells
derived from a single parent.

Cloning happens naturally

identical twins or triplets are clones.

Cloning is also widespread in agriculture and horticulture, and has been
used for many years to propagate new plants from cutting, taken from
roots, stems or leaves.

Animal clones can be produced after in vitro (in a lab environment) fertilization.

The ball of cells formed as the zygote begins to divide can be separated into
several parts in a

dish and each part can go on to form a genetically identical

Cells from a newly fertilized eggs are not differentiated and have not specialized
into the different cells they will become.

The first successful clone made from an adult animal was Dolly the sheep in
1997 in Edinburgh, Scotland.

Dolly was created from fusing the ovum with the mammary cell of an adult


Interactive Cloning

Therapeutic Cloning

Therapeutic cloning is used to produce tissue or even organs that may be
needed by human patients.

Human embryos are used as a source of embryonic stem cells, which are
undifferentiated and can become any type of human cell.

The value of the stem cells is that they could be used to repair damaged
parts of the body, such as liver or kidney, or brain because they will

become those tissues.

There are many ethical issues that arise when human cloning is considered
and stem cell research has been banned in some countries.

Currently, embryos are not specially created for the purpose of
therapeutic cloning.

Embryos that are used come from the in vitro fertilization (IVF) process
and are surplus embryos that were not implanted into the mother.

Ethic and Therapeutic Cloning

There are 2 types of cloning

reproductive and therapeutic.

Reproductive cloning involves an embryo that has been created and
implanted into the surrogate mother, where it will develop into a new

In therapeutic cloning process, no sperm fertilization is needed nor is it
necessary to implant an embryo into the uterus to create a child.

In the future, human therapeutic cloning could begin with the extraction of a nucleus
from a donated egg.

This nucleus holds all the genetic material from the donor. Scientists might then take
a body cell from their patient and extract the nucleus from it.

The patient might need a stem cell transplant to treat a health condition or disease.

The patient’s nucleus would be substituted into the egg cell so that the egg then
contains the patient’s genetic material.

The egg could be stimulated to divide, the stems cells could be isolated and infused
into the patient where they are needed to restore structure or function.

One of the major benefits of therapeutic cloning is that the stem cells
can give rise to any cell type in the body.

Another benefit is that there is no risk of immunological rejection
because it’s the patient’s own genetic material.

Therapeutic cloning could reduce waiting times for organ transplants
as well as eliminating the immunological concerns.


Therapeutic cloning is still in research, and it uses unused IVF embryos. Is it ok
to take it to the next stage and create patient

specific embryos?

Some women are willing to donate eggs but is it ethical to buy them from
willing donors?

Because the embryonic stem cells are genetically identical to the patient there
is no need for immunosuppressant drugs and no danger of rejection. Is this a
useful argument to supporting therapeutic cloning?

Since embryonic stem cells can develop into any cell type, how can the doctor
be certain that the implanted cells will develop into the correct cells and not
some other cell type such as cancer cells. Are these risks worth taking?

How can animal clones be produced?

What was the first successful clone from an adult animal. When was it?

What is therapeutic cloning? How is it done?

What is therapeutic cloning used for?

What are some benefits of therapeutic cloning?

What are some ethical issues with therapeutic cloning?

Assessment Statements

Define clone

Outline a technique for cloning using differentiated animal cells.

Discuss the ethical issues of therapeutic cloning in humans.