2. Genetic Engineering
4.4.1 Outline the use of polymerase chain reaction (PCR)
to copy and amplify minute quantities of DNA.
Details of methods are not required.
4.4.2 State that, in gel electrophoresis, fragments of DNA
move in an electric field and are separated according to
their size.
4.4.3 State that gel electrophoresis of DNA is used in
DNA profiling.
4.4.4 Describe the application of DNA profiling to
determine paternity and also in forensic investigations.
3. Genetic Engineering
Aim 8: There is a variety of social implications stemming
from DNA profiling, such as identity issues for a child
who learns unexpectedly who his or her biological father
is, self-esteem problems for someone who learns he is not
a father, problems in relationships where the male partner
learns that he did not father a child, but also relief for
crime victims when those responsible for the crime are
identified and convicted, sometimes decades later.
4. Genetic Engineering
TOK: A comparison could be made between blood groups
and DNA profiles in their potential for determining
paternity. The difficulty in assessing the chance of two
individuals having the same profile could be discussed,
and also the success of DNA profiling in securing
convictions in some of the high-profile legal cases of
recent years.
5. Genetic Engineering
4.4.5 Analyse DNA profiles to draw conclusions about
paternity or forensic investigations.
The outcomes of this analysis could include knowledge of
the number of human genes, the location of specific genes,
discovery of proteins and their functions, and evolutionary
relationships.
Aim 7: Online bioinformatics simulations are available.
6. Genetic Engineering
Aim 8: We can either emphasize the large shared content
of the human genome, which is common to all of us and
should give us a sense of unity, or we can emphasize the
small but significant allelic differences that create the
biodiversity within our species, which should be treasured.
Differences in the success of human races in coping with
the modern world and the threat to some small human
tribes could be mentioned. It is important to stress parity
of esteem of all humans, whatever their genome.
7. Genetic Engineering
TOK: The Human Genome Project was an international
endeavour, with laboratories throughout the world
collaborating. However, there were also efforts in some
parts of the world to gain commercial benefits from the
outcomes of the project.
The data from the Human Genome Project can be viewed
in different ways: it could be seen as a complete account
of what makes up a human, if one takes a reductionist
view of life, or, alternatively, as merely the chemical
instructions that have allowed a huge range of more
significant human characteristics to develop. This could
lead to a discussion about the essential nature of humanity.
8. Genetic Engineering
4.4.6 Outline three outcomes of the sequencing of the
complete human genome.
4.4.7 State that, when genes are transferred between
species, the amino acid sequence of polypeptides
translated from them is unchanged because the genetic
code is universal.
9. Genetic Engineering
Aim 8: There is an ethical or moral question here: whether
it is right to change the genetic integrity of a species by
transferring genes to it from another species. The
discussion could include the wider question of selective
breeding of animals, and whether this is distinctively
different and always acceptable. The possibility of animals
suffering as a result of genetic modification could be
considered.
10. Genetic Engineering
4.4.8 Outline a basic technique used for gene transfer
involving plasmids, a host cell (bacterium, yeast or other
cell), restriction enzymes (endonucleases) and DNA
ligase.
The use of E. coli in gene technology is well documented.
Most of its DNA is in one circular chromosome, but it also
has plasmids (smaller circles of DNA). These plasmids
can be removed and cleaved by restriction enzymes at
target sequences. DNA fragments from another organism
can also be cleaved by the same restriction enzyme, and
these pieces can be added to the open plasmid and spliced
together by ligase. The recombinant plasmids formed can
be inserted into new host cells and cloned.
11. Genetic Engineering
4.4.9 State two examples of the current uses of genetically
modified crops or animals.
Examples include salt tolerance in tomato plants, synthesis
of beta-carotene (vitamin A precursor) in rice, herbicide
resistance in crop plants and factor IX (human blood
clotting) in sheep milk.
Aim 8: The economic benefits of genetic modification to
biotechnology companies that perform it could be
considered. Also mention the possibility that harmful
changes to local economies could result, and the danger
that wealth could become more concentrated in a smaller
percentage of the population if expensive but profitable
new techniques are introduced. In this respect, inequalities
in wealth may become greater.
12. Genetic Engineering
4.4.10 Discuss the potential benefits and possible harmful
effects of one example of genetic modification.
Aim 8: There are ethical questions here about how far it is
acceptable for humans to change other species, as well as
other ecosystems, in order to gain benefit for humans.
13. Genetic Engineering
TOK: This is an opportunity to discuss how we can assess
whether risks are great enough to justify banning
techniques and how the scientific community can inform
communities generally about potential risks. Informed
decisions need to be made but irrational fears should not
be propagated. Consideration could be given to the
paradox that careful research is needed to assess the risks,
but performing this research in itself could be risky. Do
protesters who destroy trials of GM crops make the world
safer?
14. Genetic Engineering
4.4.11 Define clone.
Clone: a group of genetically identical organisms or a
group of cells derived from a single parent cell.
4.4.12 Outline a technique for cloning using differentiated
animal cells.
Aim 8: Ethical questions about cloning should be
separated into questions about reproductive cloning and
therapeutic cloning. Some groups are vehemently opposed
to both types.
15. Genetic Engineering
4.4.13 Discuss the ethical issues of therapeutic cloning in
humans.
Therapeutic cloning is the creation of an embryo to supply
embryonic stem cells for medical use.
16. Polymerase Chain Reaction (PCR)
Sometimes you only have a very small sample of DNA.
The polymerase chain reaction (PCR for short) can make
multiple copies of minute quantities of DNA very
quickly.
This process is done without the need of bacteria.
The sample of DNA is repeatedly heated and cooled, in
the presence of an enzyme, DNA polymerase and
nucleotides.
The heating opens the DNA double helix.
The DNA polymerase attaches the nucleotides.
18. Gel Electrophoresis
Gel Electrophoresis is a process used to separate
fragmented pieces of DNA according to their charge and
size.
DNA is made up of a lot of repeated nucleotide sequences
(junk DNA). Around 90% of our DNA is junk DNA.
The frequency of junk repeats is characteristic for an
individual, just as fingerprints or iris patterns are unique.
This pattern enables the DNA to be exactly matched to a
person.
Gel electrophoresis is used in DNA profiling.
19. Gel Electrophoresis
DNA can be cut into lengths using restriction enzymes.
This produces fragments called Restriction Fragment
Length Polymorphisms (RFLPs).
DNA is negatively charged, so these fragments can be
separated in an electric field.
The negatively charged fragments move towards the
anode (positive terminal).
The smaller fragments move further than the larger ones.
This produces a banding pattern, unique for each
individual.
21. Ref: Advanced Biology, Kent
Gel Electrophoresis
can be used in
criminal
investigations
Gel
Electrophoresis
22. DNA Profiling
DNA profiling is sometimes called DNA fingerprinting.
Gel electrophoresis can be used in DNA profiling.
Two major uses of DNA profiling are:
Criminal investigations.
Paternity testing.
The only major worry about the accuracy of DNA
profiling is the risk of contamination of samples.
23. Genetic Screening
Genetic screening is the testing of an individual for the
presence or absence of a gene.
This can be used to test for certain diseases of which the
gene responsible is known.
The question of whether genetic screening techniques
should be used in human populations has been widely
discussed.
There are potential advantages but also possible
disadvantages.
24. Advantages of Genetic Screening
1. Fewer children with genetic diseases are born.
Men or women who are carriers of an allele that causes a genetic
disease could avoid having children with the disease by choosing a
partner who has been screened and found not to be a carrier of the
same allele.
1. Frequency of alleles causing genetic disease can be reduced.
Couples who know that they are both carriers of a recessive allele that
causes a genetic disease could use IVF to produce embryos screened
for the allele. Embryos that do not carry the allele could be used.
1. Genetic diseases can be found and treated more effectively.
If some genetic diseases are diagnosed when a child is very young,
treatments can be given which prevent some or all of the symptoms of
the disease. PKU is an example of this.
25. Disadvantages of Genetic Screening
1. Frequency of abortion may increase.
If a genetic disease is diagnosed in a child before birth, the
parents may decide to have it aborted. Some people believe
that this is unethical.
1. Harmful psychological effects.
If a person discovers by genetic screening that they have a
genetic disease or will develop a disease when they are older,
this knowledge might cause the person to become depressed.
1. Creation of a genetic underclass.
People who are found to have a genetic disease may be refused
jobs, life insurance and health insurance and be less likely to
find a partner.
26. The Human Genome Project (HGC)
Genome: the complete set of genetic material of an
organism. Humans have about 30,000-40,000 genes
It is estimated that there are about 3.3billion nucleotides
in the human genome.
The human genome project is an international cooperative
venture to sequence the complete human genome.
Many research groups around the world are working out
the nucleotide sequence of the different chromosomes, or
parts of chromosomes.
It was started in 1990 and was originally estimated to take
15 years but was finished in 2003.
27. The Human Genome Project (HGC)
There are possible advantageous outcomes from the
HGC:
It should lead to the understanding of many genetic disorders.
We will be able to easily identify genes that cause genetic disorders
and test people for them by making gene probes.
It will allow the production of new drugs based on DNA base
sequences of genes or the structure of proteins coded for by
these genes.
Research into a particular disease can now focus on only the
gene (s) that are relevant to the disease.
It can provide more information about evolutionary paths by
comparing similarities and differences in genes between
species.
28. Genetic Engineering
Genetic material can be transferred between species.
This can occur because the genetic code is universal to
all living organisms.
The process used to transfer genetic material is called
Genetic Engineering
it is also known as Recombinant DNA technology.
For genetic engineering you need:
The gene to be transferred from the donor organism.
Restriction enzymes (restriction endonucleases).
Ligase enzymes
A host cell (usually a bacterium) and their plasmids (circular
rings of DNA.
29. Genetic Engineering
Potential uses of genetic engineering fall into three
categories:
To produce a protein product.
Human growth hormone.
Endow a particular organism with a characteristic it did not
previously possess.
Pest resistance in crops.
To create more copies of a gene.
So it can be studied more.
30. Genetic Engineering
The general steps in genetic engineering are:
Circular rings of DNA called plasmids are obtained from a
bacterium (E. Coli is commonly used).
The plasmids are cut using a particular restriction enzyme
leaving sticky ends on the plasmid.
The same restriction enzymes are used to cut the required gene
from the donor organism, leaving the same sticky ends.
The gene and plasmids are combined and the gene is spliced
into the plasmid using ligase enzymes.
The recombinant plasmid is reinserted into the bacterium and
allowed to multiply.
33. Genetically Modified Organisms
Organisms that have had genes transferred to them are
called Genetically Modified Organisms (GMOs) or
transgenic organisms.
Some examples of GMOs are:
Herbicide resistance in crops.
Sheep that produce human blood clotting factor IX.
Salt tolerance in plants.
Delayed ripening in tomatoes (Flavr-Savr™).
Bacteria use to produce insulin and clotting factor VIII.
Bt Corn resistant to insects.
34. Herbicide Resistance
Herbicide resistance in crops:
Almost all plants are killed by the herbicide glyphosphate.
A gene for resistance to glyphosphate was discovered in a
bacterium.
This gene has been transferred to maize and other crops.
The transgeneic crops can be sprayed with glyphosphate to kill
the weeds but not the crop.
35. Blood Clotting Factor IX in Sheep
Sheep that produce human blood clotting factor IX.
A gene for the production of the human blood clotting factor IX
was inserted into sheep.
They produce the clotting factor in their milk, which can be
collected and the clotting factor extracted.
The clotting factor can be administrated to humans.
36. Gene Therapy
Gene therapy is the treatment of genetic disorders by
altering the genome.
Gene therapy involves the replacement of defective genes
with gene with the correct functioning alleles.
Examples of where gene therapy has been tried include:
Treatment of cystic fibrosis
Treatment of SCID (severe combined immune disorder).
Treatment of thalassemia.
37. Benefits and harmful effects of Bt Corn
Bt corn contains a gene from Bacillus thuringiensis which
produces a protein toxic to specific insects( European corn
borer).
Benefits:
1. Damage caused by insect reduced.
2. More expensive, but the difference is less than one extra
application of insecticide.
3. Non Bt corn needs to be checked often for signs of the
borer.
4. Less insecticide needed means less impact on the
environment.
5. Reduces the infection with fungus also.
38. HARMFUL EFFECTS OF Bt CORN
1. Will also kill some other insects.
2. Insects may develop resistance to Bt toxin because they
are exposed to it all the time.
3. Insects also make Bt spray useless as insecticide( Bt spray
is safe for humans and environment)
4. It is difficult to prevent pollent (with Bt gene) from
travelling outside the field where Bt corn is grown.
-it may fertilise organically grown non Bt corn which can no
longer be sold as organic corn.
- It may fertilise wild relatives and makethem more resistant
to insects and have them dominate the niche they live in
resulting in loss of biodiversity.
39. Cloning
Clone is a group of genetically identical
organisms or a group of cells artificially
derived from a single parent.
The technique for cloning using
differentiated cells is mostly somatic cell
nuclear transfer but the use made of the
produced cells can be quite different like
reproductive and therapeutic cloning.
40. REPRODUCTIVE CLONING
Reproductive cloning creates a new individual( Dolly was the
first cloned sheep).Cloning using differentiated cell.
Steps involved in reproductive cloning
1. From the original donor sheep to be cloned, a somatic cell
(non-gamete cell) from the udder was collected and
cultured. Nucleus was removed from the cultured cell.
2. An unfertilized egg was collected from another sheep and
its nucleus was removed.
3. Using a zap of electric current, the egg cell and the
nucleus from the cultured somatic cell were fused
together.
41. 4.The new cell developed in vitro in a similar way to a zygote
and started to form an embryo.
5. The embryo was placed in a womb of surrogate mother
sheep.
6. The embryo developed normally.
7. Dolly was born, and was presented to the world as a clone
of the original donor sheep.
42. Therapeutic cloning (cloning using undifferentiated
cells)
In some cases, scientists are not interested in making an
organism but simply in making copies of cells. This is
called therapeutic cloning.
In therapeutic cloning human embryos are produced, the
cells are referred to as embryonic stem cells
Aim is to develop cells which have not yet gone through
the process of differentiation.
The cells can grow into any of a large number of different
specialised tissues.
This cloning aims at cell therapy where diseased cells are
replaced with healthy cells.
43. Use of embryonic stem cells
Growing skin to repair a serious burn.
Growing new heart muscle to repair an
ailing heart.
Growing new kidney tissue to rebuild a
failing kidney.
Bone marrow transplants for patients with
leukemia.
44. Ethical Issues of therapeutic cloning in
humans
Arguments in favour of therapeutic cloning
1. Ability to cure serious diseases with cell therapy,
currently leukemia and in the future possibly cancer and
diabetes.
Arguments against therapeutic cloning
1.Fears of it leading to reproductive cloning.
2. Use of embryonic stem cells involves the creation and
destruction of human embryos
3. Embryonic stem cells are capable of many divisions and
may turn into tumours.
45. IBO guide:
4.4.1 Outline the use of polymerase chain reaction (PCR)
to copy and amplify minute quantities of DNA.
Details of methods are not required.
4.4.2 State that, in gel electrophoresis, fragments of DNA
move in an electric field and are separated according to
their size.
4.4.3 State that gel electrophoresis of DNA is used in
DNA profiling.
4.4.4 Describe the application of DNA profiling to
determine paternity and also in forensic investigations.
46. IBO guide:
4.4.5 Analyse DNA profiles to draw conclusions about
paternity or forensic investigations.
4.4.6 Outline three outcomes of the sequencing of the
complete human genome.
4.4.7 State that, when genes are transferred between
species, the amino acid sequence of polypeptides
translated from them is unchanged because the genetic
code is universal.
47. IBO guide:
4.4.8 Outline a basic technique used for gene transfer
involving plasmids, a host cell (bacterium, yeast or other
cell), restriction enzymes (endonucleases) and DNA
ligase.
4.4.9 State two examples of the current uses of genetically
modified crops or animals.
4.4.10 Discuss the potential benefits and possible harmful
effects of one example of genetic modification.
48. IBO guide:
4.4.11 Define clone.
Clone: a group of genetically identical organisms or a
group of cells derived from a single parent cell.
4.4.12 Outline a technique for cloning using differentiated
animal cells.
4.4.13 Discuss the ethical issues of therapeutic cloning in
humans.
Therapeutic cloning is the creation of an embryo to supply
embryonic stem cells for medical use.
