DNA recombinant Technology (1)

8/7/2019 DNA recombinant Technology (1)

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DNA recombinant

technology



A series of procedures used to

recombine DNA segments.. Under certain conditions, a recombinant DNA

molecule can enter a cell and replicate.

Definition of recombinant DNAtechnology()



History of recombinant DNA

technology

Recombinant DNA technology is one

of the recent advances inbiotechnology, which was developedby two scientists named Boyer and

Cohen in 1973.



Basic principle of recombinant

DNA technology

The DNA is inserted into another

DNA molecule called µvector¶()

. The recombinant vector is then

introduced into a host cell where itreplicates itself, the gene is thenproduced



Basic principle of recombinant

DNA technology



Applications of

Recombinant DNATechnologyLarge-scale production of humanproteins by geneticallyengineered bacteria.

Such as : insulin, Growth

hormone, Interferons andBlood clotting factors (VIII & IX)



Production of Human

Insulin() 1) Obtaining the human insulin geneHuman insulin gene can be obtained bymaking a complementary DNA (cDNA) copyof the messenger RNA (mRNA) for human

insulin.



2)Joining the human insulin geneinto a plasmid() vector

The bacterial plasmids and the cDNA aremixed together. The human insulin gene

(cDNA) is inserted into the plasmid throughcomplementary base pairing at sticky ends.



3)Introducing the recombinantDNA plasmids into bacteria

The bacteria E.coli is used as the host cell. If E.

coli and the recombinant plasmids are mixedtogether in a test-tube.



4)Selecting the bacteria whichhave taken up the correct

piece of DNAThe bacteria are spread onto nutrient agar. Theagar also contains substances such as anantibiotic which allows growth of only the

transformed bacteria.



Vaccinedevelopment (

)The surface antigen of Plasmodium

falciparum, one of the 4 species of malaria

has been transferred to E. coli to produceamounts large enough to develop a vaccine

against this form of malaria(). It

works well enough for people who will

visit a malarious region for a relativelyshort period of time



Hemophilia() A andB

The genes encoding factors 8 and 9 are on the X chromosome.

Like other X-linked disorders, hemophilia A and B are foundalmost exclusively in males because they inherit just a singleX chromosome, and if the gene for factor 8 (or 9) on it isdefective, they will suffer from the disease.

There are many different mutant versions of the genes forfactors 8 and 9. Although some produce only a minor effect on the function of their protein, others fail to produce anyfunctioning clotting factor.



Treating Hemophilia A and B

Factor 8 and 9 can be extracted from donated blood, usually

pooled from several thousand donors, and purified. Injections of

this material can halt episodes of bleeding in hemophiliacs and

have allowed countless young men to live relatively normal lives.However, blood contaminated with the human immunodeficiency

virus (HIV) was unknowingly used to manufacture preparations of

factors 8 and 9. Many have since died of AIDS.



The Future of Treating Hemophilia Aand B

all donated blood is now tested to see if thedonor has been infected with HIV (as well ashepatitis B and C);

plasma-derived preparations of factors 8 and 9are now treated with heat and/or solvents todestroy any viruses that might be present ;

recombinant factor 8 and recombinant

factor 9 made by genetic engineering are nowavailable.

Now the treatment become more safety!



Still in the experimental stages, it may be possible totransfer the gene for normal adult hemoglobin intomarrow stem cells of an individual with sickle-cell

anemia(). The goal is to promote thegrowth of enough cells to produce enough normalhemoglobin to alleviate the symptoms of sickle-cellanemia. One hundred percent (100%) is NOT required to attain the alleviation of symptoms.

Gene therapy for genetic diseases



Safety Issues in relation to

Recombinant DNA TechnologyAs bacteria is commonly used in recombinant DNA work,there has always been a concern among scientists and aworry among people that there is a possibility that a clone

of highly pathogenic recombinant bacteria were made byaccident, then escaped from the laboratory and caused anepidemic for which no drugs were available.

Recombinant DNA Advisory Committee (RAC) wasestablished in 1974 in the United States, whichresponds to public concerns regarding the safety of manipulation of genetic material through the use of recombinant DNA techniques.



2 types of control : physical

containment and biologicalcontainment ()

Effective biological safety programs were

operated in a variety of laboratories, whichinclude a set of standard practices generallyused in microbiological laboratories, andspecial procedures, equipment and laboratoryinstallations that provide physical barriers of varying degrees.



In considering biological containment, thevector (plasmid, organelle, or virus) for therecombinant DNA and the host (bacterial,plant, or animal cell) in which the vector ispropagated in the laboratory will be consideredtogether.

(i) survival of the vector in its host outside the

laboratory, and (ii) transmission of the vectorfrom the propagation host to other non-laboratory hosts.

Biological containment



Dangerous of DNArecombinant technology

It is always possible that anantibiotic-resistant plasmid could beaccidentally incorporated into adangerous pathogen with seriousmedical consequences.



http://www.ied.edu.hk/biotech/eng/classrm/explain/gene5.htm

DNA recombinant Technology (1)

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