genetic engineering(mtsts)

Ma. Lunie Fe Bianca M. Otacan BMLS-1C MTSTS 10-02-14

Chapter 7

Genetic engineering

7.1: Genetic Engineering: An overview

Genetic engineering involves methods, techniques, and procedures used in gene

manipulation. The oldest of these is the recombinant DNA (rDNA) technique, or gene splicing.

The first recombinant DNA was created by molecular biologist Paul Berg in 1972 from the

cancer-causing monkry virus SV-40 and the virus lambda. This marked the birth of the field of

genetic engineering. The method of producing insulin using genetic engineering was discovered

in 1979. This is the transgenic drug in biopharming.

7.2: DNA Cloning

The process of creating copies, or clone, of a single gene or DNA segment is known as

DNA Cloning. DNA cloning can be cell-based or cell-free (using the polymerase chain

reaction). Cell-based cloning is carried out as follows:

1. Obtaining DNA Fragments-isolation of the desired DNA can be done by restriction-

endonuclease digestion, etc.

2. Joining the vector-the isolated DNA fragments can be transferred into a living cell

through the use of a cloning vehicle known as a “vector”.

3. Introduction to host cell-“trasnformation” because of the host may be altered due to the

fusion of the foreign DNA with the native DNA.

4. Selection-involves determining which host cells have successfully replicated the desired

genes.

5. Expression-involves the genetic expression of the received DNA.

7.3: Genetic Diagnosis and Screening

The two ways by which DNA can be analyzed are by

direct test (that is, direct examination of the genes)

fast and sensitive but it can only be used if the defective gene is known.

An example of a direct DNA test is the mutation analysis for cystic

fibrosis.

indirect test (that is, use of markers or linkage analysis)

it is used if the type of gene mutation that causes the disease is not yet

identified.


In this case, genetic markers, which are DNA sequences that have been

traced to specific locations on chromosomes, are used.

Linked markers are a set of markers close to a particular gene.

Diagnostic techniques used in Genetic Diagnosis and Screening Polymerase Chain Reaction

the PCR process:

step 1: Denaturation-breaking double stranded DNA

step 2: Annealing-binding of a primer to a DNA strand

step 3: Extension-elongation od DNA strand

Ligase Chain Reaction

Ligase Chain Reaction-an alternative procedure to PCR that minimizes impurities

associated with the PCR assay.

Antisense Technology-inhibits a gene function by complementary base pairing to the

genetic target. Provides the potential for “turning off” selected genes.

Transgenetic technology-paves the way for introducing foreign genes into experimental

animals to make them transgenic.

Implications of Genetic Testing

Genetic Discrimination-those who are at risk for certain genetic disorders can be denied

life and/or health insurance.

Eugenics-negative eugenics is the belief that the human population can be improved by

preventing the reproduction of indiduals with undesirable traits.

Genetic Determinism-this is the belief that aperson’s behavior, physical characteristics,

and personality are dtermined by his or her genes.

Pre-natal Diagnosis

Prenatal screening involves testing for diseases or conditions of afetus.

7.4: Applications of Genetic Engineering

The tehcnological innovations in genetic engineering offer remarkable solutions to

problems in health, food shortage, and pollution. With the advancements in technology, genetic

engineering has unlimited potential for enhancing the quality of human life.

Applications of Genetic Engineering in Medicine


Can be categorized into diagnosis (pre- and postnatal) and treatment. Techniques in

genetic engineering include sperm banking and in vitro fertilization.

In vitro fertilization steps:

Stimulants-also known as superovulation because multiple eggs are stimulated and

brought to maturation and ovulation.

Follicular aspiration-involves the retrieval of eggs from the follicles inside the ovary.

Insemination and fertilization-involves the mixing of the male’s sperm with the

female’s eggs. Fertilization can be done in two ways: allowing the sperm to naturally

enter the egg, or injecting the sperm into the egg in a process known as intracytoplasmic

sperm injection.

Embryo culture-the fertilized egg divides and becomes an embryo.

Embryo transfer-the resultant embryo is transferres to the female’s uterus through a thin

tube.

Reasons for performing IVF

Main reason is infertility.

Risks associated with IVF

Physocological stress and depression

Bloating

Abdominal pain

Moodswings

Headaches

Ovarian hyperstimulation syndrome

Other side effects of fertility drugs

Higher probability of giving birth to premature babies

Higher probability of multiple pregnancy

Sperm banking

A facility or place where sperm is stored and kept viable under controlled conditions. The

sperm stored in such a facility can be used for a number of purposes:

Artificial insemination-involves injection of sperms into the female’s vagina or cervix


Surrogacy arrangments and creating embryos for embryo donation

Resarch or educational purposes

Personal purposes-this includes preserving the reproductive capacity in males who

undergo surgery, chemotherapy, and so on.

Sex selection and prediction

The attempt to control the sex of one’s offspring is knwon as sex selection. One of the

reasons for sex selection is “ family balancing”, that is to have equal or an almost equal number

of daughters and sons. The medical benefits of sex selection include the possibility of preventing

the transmission of sex-linked diseases, such as hemophilia and parkinson’s disease.

Sex selection can be carried out at various stages:

Prefertilization-involves the separation of X chromosome-bearing and Y chromosome-

bearing sperms.

Postfertilization-PCR is used to determine the sex of the embryo by detecting the

presence of the sex-determining region (srY) in the embryo.

Postimplantation-techniques to determine sex during the postimplantation stage include

ultrasound, chorionic villus sampling (CVS), and amniocentesis.

Gene Therapy

A technique that involves the replacement of a disease-causing gene with normal

(therapeutic) gene. a carrier molecule known as a vector is needed to deliver the therapeutic

gene. Gene therapy is carried out as follows:

1. Isolation of the gene coding for the desired protein

2. Delivery of the gene into the cell by means of a vector

3. Integration of the gene into the host DNA

4. Synthesis of the protein

5. Delivery of the protein to the target cell to elicit the desired action.

The various types of gene therapy are described as follows:

Somatic gene therapy

Germline gene therapy

Preventive gene therapy


Some limitations of gene therapy are as follows:

The inserted gene may be considered as foreign body of the recipient so it will be

attacked and destroyed by antibodies.

There is the possibility that the virus that is used as a vector will regain its ability to

induce disease and control gene action.

Gene therapy works on a single gene, however most diseases are caused by multiple

genes.

The effect of gene therapy is short-lived because the cell are rapidly dividing.

Applications of genetic engineering in agriculture

Techniques in genetic engineering are used to manipulate the genetic material in plants

and animals. New varieties of plants with improved quality, productivity, and value are created.

Genetic modification in animals involves changing, adding, or removing genes to modify

characteristics, such as to enhance growth and confer resistance to certain diseases.

The following are some of the applications of genetic engineering in the field of agriculture:

Genetically engineered crops-have desirable traits such as increased productivity and

higher nutritional value.

Genetically engineered animals-also known as trangenic animals. Desirable traits are

introduced into animals to improve their characteristics.

Improvement in quality-food processing is improved by increased purity, more reliable

supply, cost reductions and high-yield efficiency.

Environmental benefits-crops become less dependent on pesticides, herbicides and

other chemicals that can be hazardous to the environment and farmers.

The risks of genetic engineering in agriculture are outlined as follows:

Health-related risks-risk of introducing allergens and toxins to the naturally safe food,

which can cause unusual immune reactions.

Environmental-related risks-may accidentally result in organisms with new genetic

make ups, transgenic crops might cross pollinate creating another variety with

undesirable effects on the environment.

genetic engineering(mtsts)

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