Recombinant dna technology


The recombinant DNA techniques were foremost demonstrated in 1972, the parent field of molecular biological science was about entirely an academic field of research. As recombinant DNA engineering exposed its practical potency during the 1970s, support for molecular biological science section began to utilize bit by bit more from the private instead than the public sector ( Susan. 1986 ) .

Recombinant DNA involves four procedures.

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  • Isolation
  • Restriction
  • Ligation
  • Transformation.


The giver DNA is separated from molecular components of the cell such as proteins, RNA, lipoids and saccharides. The complementary DNA is prepared from messenger RNA of retroviruses utilizing particular enzyme contrary RNA polymerase. The messenger RNA molecule can used as a templet and RNA polymerase syntheses procedure, the individual stranded Deoxyribonucleic acid can be used as a templet for dual isolated Deoxyribonucleic acid synthesis. Recently the research workers developed complementary DNA from chemical procedure. They developed finale from machine-controlled chemical synthesis of oligonucleotides. It contains 15 to 100 bases and bring forth DNA sequences ( Griffiths et al 2002 ) .

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The plasmid Acts of the Apostless as a cloning vector, provides reproduction of cloned cistron inside the host cell. Plasmids replicate expeditiously in bacterial hosts because each plasmid possesses an beginning of reproduction which is acknowledged by the DNA polymerase and other proteins that usually replicate the bacterium ‘s chromosomes ( Brown T.A 2002 ) . Vectors must be in little size for use. They must besides hold convenient limitation sites at which the Deoxyribonucleic acid to be cloned may be inserted. Some general classes- plasmid vectors, bacteriophage vectors.


The Deoxyribonucleic acid can be broken into set of limitation fragments harmonizing to the place of the limitation sites utilizing physically shearing it or by enzymatically digesting it which endonucleases. Eg. EcoRI.

The EcoRI makes cut merely G and A bases. The EcoRI limitation enzyme identifies six nucleotide pair sequence in the Deoxyribonucleic acid of any being.

5′-GAATTC-3 ‘

3′-CTTAAG-5 ‘

This procedure of section is called a DNA palindrome which explains the both strands have same nucleotide sequence but antiparallel placement. The limitation enzyme of EcoRI doing a individual cut in a round Deoxyribonucleic acid molecule such as plasmid, the cut opens up the circle, and the ensuing additive molecule has sticky terminals. If the two different Deoxyribonucleic acid molecules have same gluey terminal bring forthing limitation enzyme, the fragments of each will hold the same complementary sticky terminals, enabling them to crossbreed with each other the appropriate salt and temperature conditions in trial tubing ( Griffiths et al 2002 ) .


Ligase is chiefly used to fall in two DNA fragments and the procedure called as ligation. It is assorted with a different Deoxyribonucleic acid molecule. The two DNA molecule sites can crossbreed to each other through their reconciliation gluey ends to organize a recombinant molecule. The recombinant molecules do non hold covalent bond on rear sugar medieties, the DNA ligase used to seal the sugar molecules and anchor which creates phosphodiester bonds at the functions.DNA ligase widely used in lab and it is derived from the bactriophage T4. T4 DNA ligase will ligates blunt terminals of Deoxyribonucleic acid fragments and it is less efficient and more concentration in invitro surveies ( Lizabeth A 2002 ) ,

The foreign atoms enter into bacteriums by two ways.

  • Transformation
  • Transduction.

In transmutation, recombinant DNA molecule enters into bacteriums cells. In traditionally, the cells were incubated in Ca salt solution to do their weakly.

In transduction, the recombinant molecule is combined with phage caput and tail proteins from one cell to another utilizing bacteriophage vector. They inject their Deoxyribonucleic acid lading into the bacterial cells. The new recombinant Deoxyribonucleic acid or offspring phages transporting the recombinant DNA molecule depends on the vector used ( Griffiths et al 2002 ) .

Applications of recombinant Deoxyribonucleic acid

  • It produces basic apprehension of enzymology.
  • It is new attack to detecting the map of new cistron

( Reverse genetic sciences ) .

  • Correct endogenous familial defects ( eg.sickle cell anaemia, it occurs because of mutant in hemoglobin cistron ) .
  • Designation of mutants
  • Transferring of cistrons from one being to another egg. Gene therapy.
  • One of the biggest mileposts, readying of HUMAN INSULIN utilizing recombinant DNA engineering. ( Carroll WL 1986 )


To bring forth recombinant DNA engineering and ringers of E.coli transporting parts of the ? genome inserted into the plasmid pUC19.


Materials and methods used as per the given protocol of experiment.

Some of the change done in the research lab is,

  • After the ligation mixture the 2µl of halt buffer solution added to 4 µl ligase solution.
  • In transmutation experiment, already prepared DH5I¬ competent cells were given.


Figure 1: explains sample loaded in good






Deoxyribonucleic acid cut with ECOR1


Uncut pUC19


pUC19 cut with ECOR1




pUC19 +DNA+T4 DNA ligase


pUC19 +DNA+ unfertile H2O

Lane 2 which has ? DNA + EcoRI shows six sets of fragment.

Lane 3 loaded with untrimmed pUC19 shows one visible radiation shaded set.

Lane 4 loaded with pUC19+ EcoR1 shows one visible radiation set and one dark set.

Lane 6 loaded ? DNA + EcoRI & A ; lsquo ; +’T4 ligase shows a individual set.

Lane 7 loaded with & A ; lsquo ; – & A ; lsquo ; ligase shows five sets of fragments.

Molecular weight ( Kb )

Log Kb

Distance ( millimeter )



















Graph: 1 the molecular weight of DNA fragment ( log kilobit values ) Vs distance migrated by DNA fragment from base lane to positive side of cataphoresis home base.

X-axis= distance travelled by DNA fragment

Y-axis= log molecular weight of kilobit

Distance travelled by DNA fragment

The size of pUC19 was measured from the graph plotted with log molecular wt against distance migrated by fragment.

Size of pUC19 = antilog ( log kilobit )

= antilog.29

= 1.94 kbp

Consequences of transmutation

Home plate





Competent DH5A Cells ( – control )

No growing

No growing












pUC19 +DNA+sterilewater




pUC19 +DNA+T4 DNA ligase


No growing


No growing


No growing


No growing


From the home base 4:

The E.coli DH5 stains contains the = figure of white settlements – 100

Recombinant molecules. Entire figure of settlements

= 0 -100

= 0

No transformed settlements show recombinant molecules and 100 % shows merely plasmids.

Transformation efficiency = Blue colonies x dilution factor

Sum of DNA ( plate 2 )

= 8


= 4 transforms /µg of plasmid

* Transformation efficiency = transforms /µg of plasmid



Figure 2 explains about the enzymatic activity of EcoR1 on plasmid and DNA. Deoxyribonucleic acid and Puc19 were given and restricted to little fragments by ecor1. The set of fragments separated out on molecular weight. Lane 2 and 4 the molecules assorted with ecor1.the lane 2 and 4

Given sample of ?DNA and pUC 19 were restricted utilizing EcoR1, the ?DNA was cut up in to break up by EcoR1 and set was separated out on molecular weight. Lane 2 and lane 4 showed more than one bands present. In lane 2 had more sets ( 6 ) than lane 4. It indicates the enzyme activity with ?DNA and pUC19. The enzyme acted on five limitation sites and formed six fragments of ?DNA. Harmonizing to Griffith & A ; lsquo ; s account, it has confirmed. The limitation enzyme makes two fragments of puc19. The Round signifier of puc19 converted into additive signifiers ( one dark and another light set ) .


Ligation is chiefly used to fall in two DNA fragments. It is confirmed by agarose gel cataphoresis. In lane 6, the ?DNA composite added with t4 ligase molecule, it shows one set nowadays in the well. The untrimmed puc19 formed one set and reached. In lane7 the mixture of ?DNA and mixture of limitation enzyme without ligase, it forms five fragments in the gel. Whereas the lane 6, less sum of sample loaded or little errors during sample transmutation.


The nucleic acid recombinant DNA engineering was analyzed and consequence obtained. Some jobs arise during the practical times for improper work leads to misidentify in experimental consequence. Presently this technique is chiefly used in many interventions and scientific discipline innovations. Increase the applications of recombinant DNA engineering for future coevals.


1. Susan Wright ( 1986 ) . USIRIS 2nd series page-303-360.

2. Griffiths, A.J.F. , Wessler, S.R. , Lewontin, R.C. , Gelbart, W.M. , Suzuki, D.T. , Miller, J.H. Modern Genetic Analysis ( 2nd Ed. ) . New York: W.H. Freeman and Company.

3. Carroll.W.L. , American diary of clinical nutrition volume 58 page 249s-258s.

4. Lizabeth A.A. , ( 2007 ) Fundamental of molecular biological science ( 1st Ed. ) .

5. Brown, T.A. ( 2007 ) , Essential Molecular Biology, United kigdom: Oxford university imperativeness.

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