Since its advent in the 1970s, Genetic Engineering Technology has already been
revolutionizing Biochemistry. With its useful application in the field of Medicine, Nutrition, and
Agriculture, there is no doubt that indeed it has brought numerous positive fruits to alleviate
human conditions and maladies. However, coupled with its practicality and ingenuity, this
controversial fruit of several decades of basic research on DNA, RNA, and viruses still spurs
debates among scholars from different walks of life. This paper discusses some of the fruits of
Genetic Engineering and its practical application in our lives. Some findings on its perils are
discussed in this paper as well.
The 2000 Grolier Encyclopedia of Knowledge defines Genetic Engineering as the
application of the knowledge obtained from genetic investigations to the solution of problems
such as diseases, food production, improvement of species and a lot more. Included in the
Genetic Engineering Techniques are a wide range of procedures that alter the reproductive and
hereditary processes or organisms. Depending on the problem, the procedures used may involve
species hybridization, or the direct manipulation of the genetic material itself by the
Recombinant DNA Technique.
Recombinant DNA formation is a procedure whereby segments of genetic material from
one organism are transferred to another. This is through the use of special enzymes (restriction
enzymes) that split DNA strands wherever certain sequences of nucleotides occur. This results in
a series of donor DNA fragments that can combine with similarly formed DNA fragments from
other organisms. In most experimental situations, the donor DNA fragments are combined with
viruses or with plasmids (small rings of self-replicating DNA found within cells). The virus or
plasmid vectors carry the donor DNA fragments into cells. The combined vector and DNA
fragment constitutes the recombinant-DNA molecule. Once inside a cell, this molecule is
replicated along with the hosts’ DNA each time the host divides. These divisions produce a clone
of identical cells, each having a copy of the recombinant-DNA molecule and the potential to
translate the donor DNA fragment into the protein it encodes.
Genetic Engineering paved way to Gene Therapy. In this form of technology, scientists
believe they will be able to enhance traits such as intelligence or athleticism through gene
manipulation. Technically, this is not feasible because proficiency in such traits is the result of a
complex interaction of unknown genetic determinants and environmental experiences
(Wheale and McNally, 240). Gene therapy attempts to treat and possibly cure human diseases
including genetic defects, cancer, AIDS, and other maladies with cloned genes. The most
obvious use of cloned genes is to express them and harvest their products. This has already
yielded proteins that have pharmaceutical value (Weaver and Hedrick, 450). For example
proteins that are present in only a small number of cells or only in human cells. The method is
simple in principle. A DNA sequence coding for the desired protein is cloned in a vector
adjacent to an appropriate regulatory sequence. This step is done with cDNA, because it has all
the coding sequences spliced together in the right order. Using a vector with a high copy number
ensures that many copies of the coding sequence will be present in each bacterial cell, which can
result in synthesis of the gene product at concentrations ranging from 1%-5% of the total cellular
protein (Hartl and Jones, 381). This also implies that in the future, Gene Therapy may provide
mankind purified viral proteins that can serve as safe, effective vaccines against deadly diseases.
We may be able to engineer harmless viruses that can immunize us against unrelated dangerous
viruses (Weaver and Hedrick,450).In addition ,some of the proteins produced for therapeutic
use includes the following: Atrial Natriuretic Factor for heart failure and hypertension,
Epidermal Growth Factor for burns and skin transplant, Erythropoietin for anemia and a lot
more. In the easiest sense, these proteins are produced by cloning a human gene into a plasmid
and inserting the Recombinant vector into a bacterial host. After ensuring that the transferred
gene is expressed, large quantities of the transformed bacteria are produced, and the human
protein is recovered and purified (Klug and Cummings, 594).
The first human gene product manufactured using Recombinant-DNA and licensed for
the therapeutic use was human insulin. Insulin is a protein hormone that regulates sugar
metabolism, and an inability to produce insulin results to diabetes (Klug and Cummings, 593).
Recombinant-DNA procedures involving bacteria and donor DNA fragments that translate into
proteins have led to the increased availability of important substances like Interferon for viral
infection and some forms of cancer, and growth hormone for dwarfism (Grolier Encyclopedia of
Knowledge 2000, 210). How recombinational repair works is implied by the description of how
a gap in DNA leads to the recombination intermediate. The gap is filled by DNA from a
homologous duplex and is repaired. Repair is achieved whether or not the intermediate is cut so
as to exchange flanking arms of the two helices; it only matters that the gap is filled with DNA
of the correct sequence. Although a simple gap can be filled by DNA polymerase, a more serious
problem is posed by gaps that contain DNA lesions such as thyminedimers that no longer can
base-pair; these arise when replication necessarily stops at the damaged site and must reinitiate
beyond it. The genetic information at the lesion is lost from both DNA strands and can be
retrieved only by extracting it through recombination from a homologous duplex. The newly
replicated sister DNA molecule is the most accessible source of the correct sequence (Watson et
Another is the production of vaccines against some diseases. Heretofore, vaccination
against a disease has involved the injection of killed or weakened microorganisms into a person,
with the subsequent production of antibodies by the individual’s immune system. This
procedure has always carried the risk of there being live, virulent pathogens in the vaccine
because of some error in the vaccine-producing process. Research has shown that it is the
microorganism’s outer surface that serves as the antigen that stimulates antibody formation.
Through the Recombinant DNA procedure, it is now possible to transfer the genes that control a
pathogen’s surface characteristics to a harmless microorganism and use it as a vaccine against
the particular disease (Grolier Encyclopedia of Knowledge 2000, 210).
Aside from Medicine and Research, Genetic Engineering is also applied in practical life
situations by making possible the creation of organisms with novel genotypes for practical use in
Livestock Industry (Hartl and Jones, 381). In animals, implantations of cloned genes give them
more desirable characteristics, such as disease resistance and faster growth rate (Weaver and
Hedrick, 450). In 1983, a Human Growth Hormone was placed in the early mouse embryo. The
result was a giant mouse twice its normal size. This transgenic animal received foreign gene that
was incorporated into its cells. This gene could be passed on to progeny as any normal gene
would be. This paved way to the creation of transgenic pigs whose eggs were injected with
Human Growth Hormone and Bovine Growth Hormone. The pigs did not grow to supernormal
size. However, they showed a greater than normal feed efficiency- that is, weight gain per unit of
feed. Moreover, the transgenic pigs had a much smaller amount of subcutaneous fat. This is a
benefit during the current era of concern about the adverse effects of animal fat in our diet
(Weaver and Hedrick, 452). Furthermore, the effect of growth hormone under the control of a
highly active promoter to drive transcription called Metallothioneins which are ubiquitous in the
human genome is applied and seen in a Coho Salmon. At fourteen months of age, the Coho
salmons which were subjects of the study reached 42 cm. in length and weighed 11 times their
normal weight. On the average, the Coho salmons grow in length at around 10 cm only. Not only
do the transgenic salmon become larger than normal salmon; they also mature and grow faster
(Hartl and Jones, 383).
Through the Recombinant DNA technology, human is empowered to manipulate the
genetic material of living cells more precisely than has previously been possible. For example, in
Gene Replacement or Gene Activation the cells manipulated could be somatic cells or germ cells
and the genetic manipulation may be undertaken for therapeutic or enhancement purposes
(Wheale and McNally, 211). Patients suffering from genetic diseases could be treated by
implanting a normal gene to correct the defected gene. An example is the case of a patient with
Sickle-Cell Disease. Sickle-Cell patients are homozygous for a defective β-globin gene. As a
result, they make abnormal hemoglobin. This suggests that a genetic engineering solution is
possible. Since blood cells are made in the bone marrow, removal of all the patient’s abnormal
marrow is possible. This marrow is then replaced with a marrow that has a normal gene for
hemoglobin. It would be best if the patient’s own marrow is used. This is to avoid a rejection
problem. Cloning is the key- cloned human genes are added to cells in much the same way as
recombinant-DNAs are added to bacterial cells (Weaver and Hedrick. 450).
Another application of gene therapy is on the treatment of people with heritable genetic
disorders such as Severe Combined Immuno-Deficiency (SCID). Affected individuals have no
functional immune system and usually die from what would otherwise be minor infections. An
autosomal form of SCID is caused by a mutation in the gene encoding the enzyme Adenosine
deaminase (ADA). Treatment starts with the isolation from the patient of a subpopulation of
white blood cells called T cells. These cells, which are part of the immune system, are mixed
with a genetically modified retrovirus carrying a normal copy of the ADA gene. The virus infects
the T cells, inserting a functional copy of the ADA gene into the cell’s genome. The genetically
modified T cells are grown in the laboratory to ensure that the transferred gene is expressed , and
the patient is treated by injecting a billion or so of the altered T cells into the bloodstream (Klug
and Cummings, 587).
However questions have been raised by a number of scientists and lay people on the
advisability of Genetic Engineering. Together with its advantages sprouted perils, controversies,
and debates among scholars (Grolier Encyclopedia of Knowledge 2000, 210). Some even said
that chromosome damage is attributable to genetics to a slight extent only. And that, other factors
such as smoking habits and lifestyles are some of the causes of the many forms of genetic
aberrations (Clark and Wall, 151).
In the case of protein production through cloning human genes, experts have noted that in
practice, the production of large quantities of a protein in bacterial cell is straight forward, but
there are often problems that must be overcome, because in the bacterial cell which is a
prokaryotic cell, the eukaryotic protein may be unstable, may not fold properly, or may fail to
undergo chemical modification. Though, many important proteins are currently produced in
bacterial cells. These include Human Growth Hormone, blood-clotting factors, and insulin.
Patent offices in Europe and in the United States have already issued tens of thousands of patents
for the clinical use of the products of Genetically Engineered human gene (Hartl and Jones, 383).
In the earlier part of the paper, I have discussed the advantages of injecting growth hormone to
improve the genotype of pigs. However, these benefits brought some serious health problems in
the transgenic pigs. The transgenic pigs had abnormally high incidence of stomach ulcers,
arthritis, enlarged heart, dermatitis, and kidney disease. These conditions depress appetite and
lead to higher mortality, already a significant problem in domestic pigs (Weaver and Hedrick,
452). In addition, more dangers of Genetic Engineering were seen on some attempts of changing
human genes to cure some genetic diseases.
In the case of a patient with a sickle-cell disease, one roadblock is getting a cloned gene
to function normally in the patient’s cells. For some reason they are not usually expressed and
regulated as they would be in their natural state. This might be especially serious for the globin
genes, which are normally carefully regulated so that their α- and β- globin products are
produced in roughly equal amounts. A second problem has been difficulty in transforming
immortal stem cells. Unless our gene gets into such cells, its lifetime will be brief. For these
reasons, geneticists have not yet been able to attack sickle-cell anemia with cloned genes
(Weaver and Hedrick, 450). Also, some scientists were so alarmed about the potential dangers of
introducing new genes into bacteria that they convinced the molecular biology community to
stop their controversial kind of research until it could be studied more fully (Weaver and
Hedrick, 454). One of the problems of gene therapy is its short span of effect. In order for
correction to be permanent, it is of importance to insert healthy genes into immortal stem cells,
but so far this has been a difficult task. In many other diseases, DNA replication is not effective,
and corrected cells die out after just a few days, or weeks at most (Berg and Tymoczko, 148).
Also at this time, there is no completely reliable way to ensure the public that agene will be
inserted only into the target cell or tissue. In one of the earliest clinical trials with a group of four
patients treated with retroviral vectors for severe combined immunodeficiency disease, one of
the patients had a retroviral insertion into a site that caused aberrant expression of a gene,
LMO-2 , associated with lymphoblastic leukemia (Hartl and Jones, 384).
As safety debate has subsided, ethics regarding alternation of human genes heated up.
The question will always be this: How do the Science community define a defect? Undoubtedly
in years to come, genetic engineering might not only be the answer to alleviating human
conditions rather an avenue where people could have unlimited access to pursuing positive traits
for personal vanity. Nevertheless, I do not under any circumstance reject the positive fruits of
Genetic Engineering in the field of Medicine, Livestock Industry and a lot more. The only
resolution or challenge to geneticists amidst the many and controversies they are facing is to
research and study more fully the disadvantages of Genetic Engineering and capitalize on those
faults to improve such an innovative product of Science and Technology.
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