DNA Technology

HideShow resource information
Preview of DNA Technology

First 213 words of the document:

DNA Technology
DNA Technology
DNA Technology
Gene Technology
Genetic Engineering
Genetic modification
Genetically Modified Organism (GMO): An organism that has had its DNA altered by recombinant
DNA technology
Recombinant DNA: A piece of DNA that is made of DNA from more than one species
Producing Genetically Modified Organisms
1) Isolation
Enzymes called restriction endonucleases are used to cut out the DNA fragment at specific
palindromic recognition sites. The recognition sites have a sequence of bases whose shape is
complementary to the shape of the active site of the
Some restriction endonucleases cut between two opposite
base pairs, leaving a straight edge called a blunt cut.
make staggered cuts, leaving palindromic,
complementary sticky ends.
Another method of isolating the desired DNA fragment is to convert mRNA to cDNA. This
process uses an enzyme called reverse transcriptase to form a single stranded complementary DNA
strand (cDNA). Complementary base pairing and DNA polymerase are then used to convert the single
stranded cDNA into double stranded DNA that is a copy of the original gene but without introns (pre
mRNA has already been spliced during transcription to remove introns).

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

DNA Technology
2) Insertion (In Vivo)
The DNA must be inserted into a vector to be transferred to the host cell. The vector is cut open
using the same restriction endonuclease as used to isolate the DNA fragment. This means that the
sticky ends of the DNA fragment and the vector are complementary. They are joined together using
hydrogen bonding between unpaired bases and DNA ligase to catalyse the formation of
phosphodiester bonds in the sugar phosphate backbone to produce recombinant DNA.…read more

Page 3

Preview of page 3

Here's a taster:

DNA Technology
4) Identification
Not all cells will contain plasmids with recombinant DNA because:
Not all bacterial cells take up a plasmid
Some plasmids close up again without taking up the DNA fragments as the sticky ends are
Cells containing plasmids with recombinant DNA can be identified using gene markers.
a) Antibiotic Resistance (Replica Plating)
b) Fluorescent Proteins
Incorporate the DNA fragment into the gene GPF (Green Fluorescent Protein) gene on the plasmid.…read more

Page 4

Preview of page 4

Here's a taster:

DNA Technology
5) Cloning (In Vivo)
Once cells containing the DNA fragment are identified they are cloned to produce multiple copies
with the recombinant DNA. Bacteria can be easily cloned in a fermenter with starch and heat, and
these clones will quickly and cheaply produce the desired protein such as an enzyme or a hormone
(insulin, FSH, oestrogen etc) which can then be isolated and purified.…read more

Page 5

Preview of page 5

Here's a taster:

DNA Technology
3) Strand Synthesis
The solution is heated to 70C. Thermostable DNA polymerase catalyses the formation of
phosphodiester bonds between nucleotides to form a complementary DNA strand, and thereby give
two identical double stranded DNA strands.
4) Repetition
The process is repeated, each time doubling the amount of DNA, therefore the amount of DNA
increases exponentially.
Gene Therapy
Gene therapy can be somatic or germ-line.…read more

Page 6

Preview of page 6

Here's a taster:

DNA Technology
Gene Therapy using a harmless adenovirus
The CFTR gene is isolated using a restriction endonuclease and
inserted into a harmless adenovirus (type of virus that causes coughs
and colds). The adenovirus is then inhaled by the patient, and injects
its DNA into the epithelial cells of the lungs.
Gene Therapy using a liposome
The CTFR gene is cloned and wrapped in a lipid.…read more

Page 7

Preview of page 7

Here's a taster:

DNA Technology
Locating and Sequencing Genes
DNA Probes
A DNA probe is a short, single stranded section of DNA that has been labelled either with
radioactivity (³²P that produces dark bands when exposed to photographic film) or fluorescent
proteins (that fluoresce in UV light), used to locate a particular gene.…read more

Page 8

Preview of page 8

Here's a taster:

DNA Technology
Gel Electrophoresis
All the fragments in each test tube end with the same base. Fragments are loaded into a well at one
end of the agar gel and a potential difference is applied. The phosphate group in DNA gives it a
negative charge, therefore the wells are placed at the negative end of the agar so that DNA is
attracted to the positive end. Smaller fragments move more quickly as they have less resistance.…read more


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »