gene cloning 2
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Biology Project Work
Gene Cloning
Made By-Gaurav
Roll No.
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CertificateThis to certify that Master. Gauravof Class XIIth
Science has successfully completed the project on Gene
Cloning under the able guidance of her Biology teacher
M in the academic session 2011-2012.
Roll No.
Teachers Signature
Principles Signature
External Examiner
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Acknowledgement
This Particular Project has been one of the amiable and
aspiring assignments to me. I pay my thanks to our biology
teacher under whose guidance I was able to
complete the work. Lastly Im thankful to our principalMr.
Shekhar Jakhodiya who gave us the opportunity to conduct
this project.
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Content
Introduction
Different Types of Cloning
Steps of Gene CloningCloning techniques
Genetic Engineering
Reasons Why E.coli Is Used For Gene Cloning
Dolly -The Sheep
Species Cloned
Risks of Cloning
Should Human Be Cloned?
Applications of Gene Cloning
Conclusion
References
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Introduction
Genes
A gene is a short piece of DNA, which tells the body how to build a specific
protein, i.e., itcarry information that is necessary to make a protein. There are
approximately 30,000 genes in each cell of the human body. The combinationof all genes makes up the blueprint for the human body and its functions.
Cloning
Clonesare two or more organisms with identical genetic make-up derived, by
ASEXUAL REPRODUCTION, from a single common parent or ancestor, such as
identical twins.
Cloning refers to processes used to create copies ofDNAfragments (molecular
cloning), cells (cell cloning), ororganisms.
Hence,
Gene cloning is the act of making copies, orclones, of a single gene.Gene cloning provides opportunity to the scientists to study the structure and
function of genes in detail. For this purpose, gene of interest is inserted into the
bacterial cell which acts as a host. The cloned gene can be used for many
research purposes like detection of diseases, gene therapy and other medical
applications.
http://en.wikipedia.org/wiki/Cloninghttp://en.wikipedia.org/wiki/Cloninghttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Molecular_cloninghttp://en.wikipedia.org/wiki/Molecular_cloninghttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Organismshttp://biotech.about.com/od/labtechniques/g/What-Is-A-Clone.htmhttp://biotech.about.com/od/labtechniques/g/What-Is-A-Clone.htmhttp://en.wikipedia.org/wiki/Organismshttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Molecular_cloninghttp://en.wikipedia.org/wiki/Molecular_cloninghttp://en.wikipedia.org/wiki/DNAhttp://en.wikipedia.org/wiki/Cloning -
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Different Types of Cloning
Cellular cloning
A useful tissue culture technique used to clone distinct lineages of cell lines
involves the use ofcloning rings (cylinders). According to this technique, a
single-cell suspension of cells that have been exposed to a mutagenic agentor
drug used to drive selection is plated at high dilution to create isolated
colonies; each arising from a single and potentially clonal distinct cell. At anearly growth stage when colonies consist of only a few of cells,
sterile polystyrene rings (cloning rings), which have been dipped in grease are
placed over an individual colony and a small amount oftrypsin is added.
Cloned cells are collected from inside the ring and transferred to a new vessel
for further growth.
Molecular cloning
Molecular cloning refers to the process of making multiple molecules. Cloning is
commonly used to amplify DNA fragments containing whole genes, but it can
also be used to amplify any DNA sequence such as promoters, non-coding
sequences and randomly fragmented DNA. It is used in a wide array of
biological experiments and practical applications ranging from genetic
fingerprinting to large scale protein production. To amplify any DNA sequencein a living organism, that sequence must be linked to an origin of replication,
which is a sequence of DNA capable of directing the propagation of itself and
any linked sequence. However, a number of other features are needed and a
variety of specialised cloning vectors (small piece of DNA into which a foreign
DNA fragment can be inserted) exist that allowprotein expression, tagging,
single strandedRNA and DNA production and a host of other manipulations.
http://en.wikipedia.org/w/index.php?title=Cloning_ring&action=edit&redlink=1http://en.wikipedia.org/wiki/Mutagenhttp://en.wikipedia.org/wiki/Selectionhttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/Trypsinhttp://en.wikipedia.org/wiki/Geneshttp://en.wikipedia.org/wiki/Promoter_(biology)http://en.wikipedia.org/wiki/Genetic_fingerprintinghttp://en.wikipedia.org/wiki/Genetic_fingerprintinghttp://en.wikipedia.org/wiki/Origin_of_replicationhttp://en.wikipedia.org/wiki/Cloning_vectorhttp://en.wikipedia.org/wiki/Protein_expressionhttp://en.wikipedia.org/wiki/RNAhttp://en.wikipedia.org/wiki/RNAhttp://en.wikipedia.org/wiki/Protein_expressionhttp://en.wikipedia.org/wiki/Cloning_vectorhttp://en.wikipedia.org/wiki/Origin_of_replicationhttp://en.wikipedia.org/wiki/Genetic_fingerprintinghttp://en.wikipedia.org/wiki/Genetic_fingerprintinghttp://en.wikipedia.org/wiki/Promoter_(biology)http://en.wikipedia.org/wiki/Geneshttp://en.wikipedia.org/wiki/Trypsinhttp://en.wikipedia.org/wiki/Polystyrenehttp://en.wikipedia.org/wiki/Selectionhttp://en.wikipedia.org/wiki/Mutagenhttp://en.wikipedia.org/w/index.php?title=Cloning_ring&action=edit&redlink=1 -
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Organism cloning
Organism cloning (also called reproductive cloning) refers to the procedure ofcreating a new multicellular organism, genetically identical to another. In
essence this form of cloning is an asexual method of reproduction, where
fertilization or inter-gamete contact does not take place. Asexual reproduction
is a naturally occurring phenomenon in many species, including most plants
and some insects. Scientists have made some major achievements with cloning,
including the asexual reproduction of sheep and cows.
Human Cloning
Human cloning is the creation of a geneticallyidentical copy of an existing or
previously existing human. The term is generally used to refer
to artificial human cloning; human clones in the form ofidentical twins are
commonplace, with their cloning occurring during the natural process of
reproduction.
There are two commonly discussed types of human cloning: therapeutic
cloning and reproductivecloning.
Therapeutic cloning involves cloning adult cells for use in medicine and is an
active area of research.
Reproductive cloning would involve making cloned humans.
A third type of cloning calledreplacement cloning is a theoretical possibility,
and would be a combination of therapeutic and reproductive cloning.
Replacement cloning would entail the replacement of an extensively damaged,
failed, or failing body through cloning followed by whole or partialbrain
transplant.
http://en.wikipedia.org/wiki/Geneticshttp://en.wikipedia.org/wiki/Humanhttp://en.wikipedia.org/wiki/Identical_twinhttp://en.wikipedia.org/wiki/Brain_transplanthttp://en.wikipedia.org/wiki/Brain_transplanthttp://en.wikipedia.org/wiki/Brain_transplanthttp://en.wikipedia.org/wiki/Brain_transplanthttp://en.wikipedia.org/wiki/Identical_twinhttp://en.wikipedia.org/wiki/Humanhttp://en.wikipedia.org/wiki/Genetics -
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Steps of Gene Cloning
Isolation of the Desired Gene: -
First step in gene cloning is the isolation of the desired part of DNA in which the
gene of interest is present. Similarly the bacterial plasmids are also isolated in
which the desired gene will be inserted. When the desired region with gene of
interest is identified, it is isolated by cutting it with restriction enzymes. As all
enzymes are proteins, restriction enzymes are also proteins which play a role of
catalysts in a chemical reaction. They cut the phosphodiester bond, a covalentbond of deoxyribose in DNA. There are specific sites on the DNA molecule called
restriction sites. These are the locations where gene of interest is isolated from
the rest of the DNA molecule by breaking the strand of DNA. Now this gene is
ready for the introduction to the vector.
Introduction of the Desired Gene into the Plasmid: -
When the gene of interest is isolated, it now needs a host cell where it can
replicate and can make multiple copies. For this purpose, plasmid is used which
is a molecule inside the bacterial cell. It has the ability to replicate out of the
bacterial chromosomal DNA. Plasmids are the best source of gene cloning as
they are able to replicate separately and independently from the bacteria's on
genetic material. They are double stranded circular molecules. When the gene
of the interest is inserted into the plasmid, the ring of the plasmid opens upgiving place to the gene to attach with it. Now the plasmid is ready for the
introduction into the host organisms as it contains a foreign gene.
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Insertion of Plasmid into the Host cell: -
Most commonly used plasmid is the Escherichia coli, specie of bacteria useful
for the human body. The plasmid with foreign gene is now inserted into the
host organism's body. Plasmid enters the host cell by two mechanisms; either it
is inserted by placing the cell incalcium chloride which will enable the plasmid
to enter the host cell or byElectroporation, in which through slight electric
current, pores will appear in the host cell's membrane, plasmid will enter
through these pores. Now the host cell is genetically modifies because it
contains the foreign within it.
Beginning of the Cloning of new Gene: -
As described above that plasmid is free of chromosomal DNA that is why when
it is inserted into the bacterial cell, it will start replicating at a very high speed
making identical copies of the desired gene. Scientists use E.coli as the host cell
for the plasmid, because it has the ability to replicate faster than any other
microorganism. It is the best microorganism used in recombinant DNA
technology.
Isolation of the Cloned gene: -
Scientists put the bacterial cell along with the culture into a culture, where it
replicates. Then the cloned gene is isolated again by using restriction enzymes
through the process known as lysis. Through this way, the cloned gene can be
isolated without any damage to the gene.
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Cloning Techniques
Embryo splitting involves dividing an eight cell embryo into single cells or
blastomeres. Transferring two of these blastomeres into an emptyzona
pellucida creates an embryo. Once the embryo reaches the blastocyst stage,
embryonic stem cells may be collected from the inner cell mass for use in
further research. A second option is to implant the embryo in a surrogate
mother, allowing it to develop fully. Offspring produced by embryo splitting will
be identical clones of one another if the embryo from which they were derived
is produced by fertilising an egg with sperm, the offspring will not be identicalto either of their genetic parents. This technique has been used successfully to
create non-human primate clones, but somatic cell nuclear transfer is the most
commonly used cloning technique.
In Intra-species cloning the nucleus of a somatic cell is taken from one
organism and placed in an enucleated egg from another member of the same
species. This method was used to produce the first cloned animal, Dolly the
sheep. It has subsequently been used to clone other species.
Inter-species cloning is more controversial than intra-species techniques
because the nucleus of a somatic cell from one organism is transferred to an
enucleated egg from a different species. Scientists have used this technique to
clone human cells by placing the nucleus of a human somatic cell in an
enucleated egg from a cow. The hybrid cells that were produced were able to
divide, but they were not permitted to develop to the blastocyst stage.
http://staff.um.edu.mt/acus1/FERTILIZATION_files/image002.jpghttp://staff.um.edu.mt/acus1/FERTILIZATION_files/image002.jpghttp://departments.weber.edu/chfam/Prenatal/images/Blastocyst.gifhttp://departments.weber.edu/chfam/Prenatal/images/Blastocyst.gifhttp://staff.um.edu.mt/acus1/FERTILIZATION_files/image002.jpghttp://staff.um.edu.mt/acus1/FERTILIZATION_files/image002.jpg -
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Genetic engineering
It is the process of cloning genes into new organisms, or altering the DNAsequence to change the protein product. Genetic engineering depends on
our ability to perform the following essential procedures.
1. Polymerase Chain Reaction
The discovery of thermostable DNA polymerases, such as Taq Polymerase,
made it possible to manipulate DNA replication in the laboratory and was
essential to the development ofPCR. Primers specific to a particular region
of DNA, on either side of the gene of interest, are used, and replication is
stopped and started repetitively, generating millions of copies of that
gene. These copies can then be separated and purified using gel
electrophoresis.
2. Restriction Enzymes
The discovery ofenzymes known as restriction endonucleases has been
essential toprotein engineering . These enzymes cut DNA at specific
locations based on the nucleotide sequence. Hundreds of
differentrestriction enzymes, capable of cutting DNA at a distinct site,
have been isolated from many different strains of bacteria. DNA cut with a
restriction enzyme produces many smaller fragments, of varying sizes.
These can be separated using gel electrophoresis or chromatography.
3. Electrophoresis
Purifying DNA from a cell culture, or cutting it using restriction enzymes
wouldn't be of much use if we couldn't visualize the DNA - that is, find a
way to view whether or not your extract contains anything, or what size
fragments you've cut it in to. One way to do th is is by gel electrophoresis.
Gels are used for a variety of purposes, from viewing cut DNA to detecting
DNA inserts andknock outs.
http://biotech.about.com/od/glossary/g/What-Is-Dna.htmhttp://biotech.about.com/od/pcr/a/PCRtheory.htmhttp://biotech.about.com/od/glossary/g/PCRdef.htmhttp://biotech.about.com/od/proteinengineering/a/restrictenz.htmhttp://biotech.about.com/od/proteinengineering/a/restrictenz.htmhttp://biotech.about.com/od/glossary/g/Enzyme.htmhttp://biotech.about.com/od/technicaltheory/a/ProtEng.htmhttp://biotech.about.com/od/technicaltheory/a/ProtEng.htmhttp://biotech.about.com/od/technicaltheory/a/ProtEng.htmhttp://biotech.about.com/od/labtechniques/g/Electrophoresis.htmhttp://biotech.about.com/od/labtechniques/g/Electrophoresis.htmhttp://biotech.about.com/od/labtechniques/g/Electrophoresis.htmhttp://biotech.about.com/od/labtechniques/g/Electrophoresis.htmhttp://biotech.about.com/od/labtechniques/g/Knockout.htmhttp://biotech.about.com/od/labtechniques/g/Knockout.htmhttp://biotech.about.com/od/labtechniques/g/Knockout.htmhttp://biotech.about.com/od/labtechniques/g/Electrophoresis.htmhttp://biotech.about.com/od/labtechniques/g/Electrophoresis.htmhttp://biotech.about.com/od/technicaltheory/a/ProtEng.htmhttp://biotech.about.com/od/glossary/g/Enzyme.htmhttp://biotech.about.com/od/proteinengineering/a/restrictenz.htmhttp://biotech.about.com/od/glossary/g/PCRdef.htmhttp://biotech.about.com/od/pcr/a/PCRtheory.htmhttp://biotech.about.com/od/glossary/g/What-Is-Dna.htm -
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4. Join Two Pieces of DNA
In genetic research it is often necessary to link two or more individual
strands of DNA, to create a recombinantstrand, or close a circular strand
that has been cut with restriction enzymes. Enzymes called DNA ligases can
create covalent bonds between nucleotide chains. The enzymes DNA
polymerase I and polynucl eot ide kinase are al so important in thi s process ,
for fi ll ing in gaps, or phosphorylat ing the 5' ends, respecti ve ly .
5. Selection of Small Self -Replicating DNA
Small circular pieces of DNA that are not part of a bacterial genome, but
are capable of self-replication, are known as plasmids. Plasmids are often
used as vectors to transport genes between microorganisms. In
biotechnology, once the gene of interest has been amplified and both the
gene and plasmid are cut by restriction enzymes, they are ligated together
generating what is known as a recombinant DNA. Viral (bacteriophage)
DNA can also be used as a vector, as can cosmids, recombinant plasmids
containing bacteriophage genes.
6. Method to Move a Vector into a Host Cell
The process of transferring genetic material on a vector such as a plasmid,
into new host cells, is called transformation. This technique requires that
the host cells are exposed to an environmental change which makes them
"competent" or temporarily permeable to the vector. Electroporation is
one such technique. The larger the plasmid, the lower the efficiency withwhich it is taken up by cells. Larger DNA segments are more easily cloned
using bacteriophage, retrovirus or other viral vectors or cosmids in a
method called transduction. Phage or viral vectors are often used
in regenerative medicine but may cause insertion of DNA in parts of our
chromosomes where we don't want it, causing complications and even
cancer.
http://biotech.about.com/od/glossary/g/Recombinant.htmhttp://biotech.about.com/od/proteintechnology/g/Vectors.htmhttp://biotech.about.com/od/labtechniques/g/Electroporation.htmhttp://biotech.about.com/od/faq/f/Retrovirus.htmhttp://biotech.about.com/od/glossary/g/regenerativemed.htmhttp://biotech.about.com/od/glossary/g/regenerativemed.htmhttp://biotech.about.com/od/faq/f/Retrovirus.htmhttp://biotech.about.com/od/labtechniques/g/Electroporation.htmhttp://biotech.about.com/od/proteintechnology/g/Vectors.htmhttp://biotech.about.com/od/glossary/g/Recombinant.htm -
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7. Methods to Select Transgenic Organisms
Not all cells will take up DNA during transformation. It is essential that
there be a method of detecting the ones that do. Generally, plasmids carry
genes for antibiotic resistance and transgenic cells can be selected based
on expression of those genes and their ability to grow on media containing
that antibiotic. Alternative methods of selection depend on the prese nce of
otherreporter proteins such as the x-gal/lacZsystem, or green
fl uorescence protein, which al low selecti on based on color and
fl uorescence , respective ly.
http://biotech.about.com/od/labtechniques/g/transgenic.htmhttp://www.bio.davidson.edu/courses/genomics/method/reporters.htmlhttp://www.bio.davidson.edu/courses/genomics/method/reporters.htmlhttp://biotech.about.com/od/labtechniques/g/transgenic.htm -
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Vectors
The vector serves as the carrier for the transfer or insertion of gene(s). Vectors
are among the essential tools for gene cloning.
eg - Agrobacterium tumefaciens, bacteriophages etc.
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Top 5 Reasons E. coli is used for Gene Cloning
The microorganismEscherichia coli have a long history of use in thebiotechnology industry and is still the microorganism of choice for most gene
cloning experiments. AlthoughE. coli is known to the general population for
the infectious nature of one particular strain (0157:H7) few people are aware of
how versatile and usefulE. coliis to genetic research. There are several
reasonsE. colibecame so widely used and is still a common host for
recombinantDNA.
1. Genetic Simplicity
Bacteria make useful tools for genetic research because of their relativelysmall
genome sizecompared to eukaryotes.E. colicells only have about 4,400 genes
whereas the human genome projecthas determined that humans contain
approximately 30,000 genes. Also, bacteria, includingE. coli, live their entire
lifetime in a haploid state, with no second allele to mask the effects of
mutations during protein engineering experiments.
2. Growth Rate
Bacteria typicallygrow much fasterthan more complex organisms.E.
coligrows rapidly at a rate of one generation per twenty minutes under typical
growth conditions. This allows for preparation oflog-phase(mid-way to
maximum density) cultures overnight and genetic experimental results in mere
hours instead of several days, months or years. Faster growth also means
better production rates when cultures are used in scaled up fermentation
processes.
http://biotech.about.com/od/glossary/g/Recombinant.htmhttp://biotech.about.com/od/casestudies/a/humangenome.htmhttp://biotech.about.com/od/technicaltheory/a/ProtEng.htmhttp://biotech.about.com/od/glossary/g/Fermentation.htmhttp://biotech.about.com/od/glossary/g/Fermentation.htmhttp://biotech.about.com/od/glossary/g/Fermentation.htmhttp://biotech.about.com/od/technicaltheory/a/ProtEng.htmhttp://biotech.about.com/od/casestudies/a/humangenome.htmhttp://biotech.about.com/od/glossary/g/Recombinant.htm -
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3. Safety
E. coliisnaturally foundin the intestinal tracts of humans and animals where it
helps provide nutrients (vitamins K and B12) to its host. There are many
different strains ofE. coli that may produce toxins or cause varying levels ofinfection if injested or allowed to invade other parts of the body. Despite the
bad reputation of one particularly toxic strain (O157:H7),E. coliare
generallyrelatively innocuous ifhandled with reasonable hygiene.
4. Conjugation and the Genome Sequence
TheE. coligenome was the first to be completely sequenced. Genetic mapping
inE. coliwas made possible by the discovery ofconjugation.E. coliis the most
highly studied microorganism and an advanced knowledge of its protein
expression mechanisms makes it simpler to use for experiments where
expression of foreign proteins and selection of recombinants is essential.
5. Ability to Host Foreign DNA
Most gene cloning techniques were developed using this bacterium and are still
more successful or effective inE. colithan in other microorganisms.E. coliis
readily transformed with plasmids and othervectors, easily
undergoes transduction, and preparation of competent cells (cells that will take
up foreign DNA) is not complicated. Transformations with other
microorganisms are often less successful.
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Dolly -The Sheep
Dolly (5 July 1996 14 February 2003) was a female domestic sheep, and the
firstmammalto be clonedfrom an adultsomatic cell, using the process of
nuclear transfer. She was cloned byIan Wilmut, Keith Campbelland colleagues
at the Roslin Institute nearEdinburgh in Scotland. She was born on 5 July 1996
and she lived until the age of six. The cell used as the donor for the cloning of
Dolly was taken from a mammary gland, and the production of a healthy clone
therefore proved that a cell taken from a specific part of the body could
recreate a whole individual.
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Birth
Dolly was born 5 July 1996 to three mothers (one provided the egg; other DNA
and a third carried the cloned embryo to term). She was created using the
technique ofsomatic cell nuclear transfer, where the cell nucleusfrom an adultcell is transferred into an unfertilizedoocyte (developing egg cell) that has had
its nucleus removed. The hybrid cell is then stimulated to divide by an electric
shock, and when it develops into a blastocystit is implanted in a surrogate
mother. Dolly was the first clone produced from a cell taken from an adult
mammal. The production of Dolly showed that genes in the nucleus of such a
mature differentiatedsomatic cell are still capable of reverting back to an
embryonic totipotentstate, creating a cell that can then go on to develop into
any part of an animal. Dollys existence was announced to the public on 22
February 1997.
Life
Dolly lived for her entire life at the Roslin Institute in Edinburgh. There she was
bred with a Welsh Mountain ram and produced six lambs in total. Her first
lamb, named Bonnie, was born in April 1998. The next year Dolly produced twinlambs Sally and Rosie, and she gave birth to triplets Lucy, Darcy and Cotton in
the year after that. In the autumn of 2001, at the age of five, Dolly developed
arthritis and began to walk stiffly, but this was successfully treated with anti-
inflammatorydrugs.
Death
On 14 February 2003, Dolly was euthanisedbecause she had a progressive lung
disease and severe arthritis. A Finn Dorsetsuch as Dolly has a life expectancy
of around 11 to 12 years, but Dolly lived to be only six years of age. A post-
mortem examination showed she had a form oflung cancer called Jaagsiekte,
which is a fairly common disease of sheep and is caused by theretrovirus JSRV.
http://en.wikipedia.org/wiki/Somatic_cell_nuclear_transferhttp://en.wikipedia.org/wiki/Somatic_cell_nuclear_transferhttp://en.wikipedia.org/wiki/Somatic_cell_nuclear_transferhttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Oocytehttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Blastocysthttp://en.wikipedia.org/wiki/Cellular_differentiationhttp://en.wikipedia.org/wiki/Totipotencyhttp://en.wikipedia.org/wiki/Welsh_Mountain_sheephttp://en.wikipedia.org/wiki/Arthritishttp://en.wikipedia.org/wiki/Anti-inflammatoryhttp://en.wikipedia.org/wiki/Anti-inflammatoryhttp://en.wikipedia.org/wiki/Animal_euthanasiahttp://en.wikipedia.org/wiki/Finnish_Dorset_(sheep)http://en.wikipedia.org/wiki/Retrovirushttp://en.wikipedia.org/wiki/Retrovirushttp://en.wikipedia.org/wiki/JSRVhttp://en.wikipedia.org/wiki/JSRVhttp://en.wikipedia.org/wiki/JSRVhttp://en.wikipedia.org/wiki/Retrovirushttp://en.wikipedia.org/wiki/Finnish_Dorset_(sheep)http://en.wikipedia.org/wiki/Animal_euthanasiahttp://en.wikipedia.org/wiki/Anti-inflammatoryhttp://en.wikipedia.org/wiki/Anti-inflammatoryhttp://en.wikipedia.org/wiki/Arthritishttp://en.wikipedia.org/wiki/Welsh_Mountain_sheephttp://en.wikipedia.org/wiki/Totipotencyhttp://en.wikipedia.org/wiki/Cellular_differentiationhttp://en.wikipedia.org/wiki/Blastocysthttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Oocytehttp://en.wikipedia.org/wiki/Cell_nucleushttp://en.wikipedia.org/wiki/Somatic_cell_nuclear_transfer -
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Cloning Of Dolly
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Species cloned
The modern cloning techniques involving nuclear transferhave been successfullyperformed on several species. Landmark experiments in chronological order:
Tadpole (1952): Many scientists questioned whether cloning had actually occurred
and unpublished experiments by other labs were not able to reproduce the reported
results.
Carp (1963): In China, embryologistTong Dizhouproduced the world's first cloned
fish by inserting the DNA from a cell of a male carp into an egg from a female carp.
He published the findings in a Chinese science journal.
Mice(1986: A mouse was the first mammal successfully cloned from an early
embryonic cell. Sovietscientists Chaylakhyan, Veprencev, Sviridova, and Nikitin had
the mouse "Masha" cloned. Research was published in the magazine "Biofizika"
volume II, issue 5 of 1987.
Sheep(1996): From early embryonic cells by Steen Willadsen. Megan and
Morag cloned from differentiated embryonic cells in June 1995 andDolly the
sheepfrom a somatic cell in 1997.
Rhesus Monkey: Tetra (January 2000) from embryo splitting
Gaur(2001): was the first endangered species cloned.
Cattle: Alpha and Beta (males, 2001) and (2005) Brazil
Cat: CopyCat"CC" (female, late 2001), Little Nicky, 2004, was the first cat cloned for
commercial reasons
Dog: Snuppy, a male Afghan houndwas the first cloned dog (2005).Rat: Ralph, the
first cloned rat (2003)
Mule: Idaho Gem, a john mule born 4 May 2003, was the first horse-family clone.
Horse: Prometea, a Haflinger female born 28 May 2003, was the first horse clone.
Water Buffalo: Samrupa was the first cloned water buffalo. It was born on February
6, 2009, atIndia's Karnal National Diary Research Institute but died five days later
due to lung infection.
Camel (2009): Injaz, is the first cloned camel.
http://en.wikipedia.org/wiki/Nuclear_transferhttp://en.wikipedia.org/wiki/Tadpolehttp://en.wikipedia.org/wiki/Carphttp://en.wikipedia.org/wiki/Chinahttp://en.wikipedia.org/wiki/Embryologisthttp://en.wikipedia.org/wiki/Tong_Dizhouhttp://en.wikipedia.org/wiki/Micehttp://en.wikipedia.org/wiki/Micehttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Domestic_sheephttp://en.wikipedia.org/wiki/Domestic_sheephttp://en.wikipedia.org/wiki/Megan_and_Moraghttp://en.wikipedia.org/wiki/Megan_and_Moraghttp://en.wikipedia.org/wiki/Megan_and_Moraghttp://en.wikipedia.org/wiki/Dolly_the_sheephttp://en.wikipedia.org/wiki/Dolly_the_sheephttp://en.wikipedia.org/wiki/Rhesus_Monkeyhttp://en.wikipedia.org/wiki/Tetra_(monkey)http://en.wikipedia.org/wiki/Gaurhttp://en.wikipedia.org/wiki/Cattlehttp://en.wikipedia.org/w/index.php?title=Alpha_and_Beta&action=edit&redlink=1http://en.wikipedia.org/wiki/Cathttp://en.wikipedia.org/wiki/CC_(cat)http://en.wikipedia.org/wiki/Little_Nicky_(cat)http://en.wikipedia.org/wiki/Doghttp://en.wikipedia.org/wiki/Snuppyhttp://en.wikipedia.org/wiki/Afghan_houndhttp://en.wikipedia.org/wiki/Rathttp://en.wikipedia.org/wiki/Rathttp://en.wikipedia.org/w/index.php?title=Ralph_(cloned_rat)&action=edit&redlink=1http://en.wikipedia.org/wiki/Mulehttp://en.wikipedia.org/wiki/Idaho_Gemhttp://en.wikipedia.org/wiki/Horsehttp://en.wikipedia.org/wiki/Prometeahttp://en.wikipedia.org/wiki/Water_Buffalohttp://en.wikipedia.org/wiki/Samrupahttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Camelhttp://en.wikipedia.org/wiki/Injazhttp://en.wikipedia.org/wiki/Injazhttp://en.wikipedia.org/wiki/Camelhttp://en.wikipedia.org/wiki/Indiahttp://en.wikipedia.org/wiki/Samrupahttp://en.wikipedia.org/wiki/Water_Buffalohttp://en.wikipedia.org/wiki/Prometeahttp://en.wikipedia.org/wiki/Horsehttp://en.wikipedia.org/wiki/Idaho_Gemhttp://en.wikipedia.org/wiki/Mulehttp://en.wikipedia.org/w/index.php?title=Ralph_(cloned_rat)&action=edit&redlink=1http://en.wikipedia.org/wiki/Rathttp://en.wikipedia.org/wiki/Afghan_houndhttp://en.wikipedia.org/wiki/Snuppyhttp://en.wikipedia.org/wiki/Doghttp://en.wikipedia.org/wiki/Little_Nicky_(cat)http://en.wikipedia.org/wiki/CC_(cat)http://en.wikipedia.org/wiki/Cathttp://en.wikipedia.org/w/index.php?title=Alpha_and_Beta&action=edit&redlink=1http://en.wikipedia.org/wiki/Cattlehttp://en.wikipedia.org/wiki/Gaurhttp://en.wikipedia.org/wiki/Tetra_(monkey)http://en.wikipedia.org/wiki/Rhesus_Monkeyhttp://en.wikipedia.org/wiki/Dolly_the_sheephttp://en.wikipedia.org/wiki/Dolly_the_sheephttp://en.wikipedia.org/wiki/Megan_and_Moraghttp://en.wikipedia.org/wiki/Megan_and_Moraghttp://en.wikipedia.org/wiki/Domestic_sheephttp://en.wikipedia.org/wiki/Soviet_Unionhttp://en.wikipedia.org/wiki/Micehttp://en.wikipedia.org/wiki/Tong_Dizhouhttp://en.wikipedia.org/wiki/Embryologisthttp://en.wikipedia.org/wiki/Chinahttp://en.wikipedia.org/wiki/Carphttp://en.wikipedia.org/wiki/Tadpolehttp://en.wikipedia.org/wiki/Nuclear_transfer -
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What are the risks of cloning?
Reproductive cloning is expensive and highly inefficient. More than 90% of cloning
attempts fail to produce viable offspring. More than 100 nuclear transfer procedures
could be required to produce one viable clone. In addition to low success rates, cloned
animals tend to have more compromised immune function and higher rates of
infection, tumor growth, and other disorders. Japanese studies have shown that
cloned mice live in poor health and die early. About a third of the cloned calves born
alive have died young, and many of them were abnormally large. Many cloned
animals have not lived long enough to generate good data about how clones age.
Appearing healthy at a young age unfortunately is not a good indicator of long-term
survival. Clones have been known to die mysteriously. For example, Australia's first
cloned sheep appeared healthy and energetic on the day she died, and the results
from her autopsy failed to determine a cause of death.
In 2002, researchers at the Whitehead Institute for Biomedical Research in
Cambridge, Massachusetts, reported that the genomes of cloned mice are
compromised. In analyzing more than 10,000 liver and placenta cells of cloned mice,they discovered that about 4% of genes function abnormally. The abnormalities do
not arise from mutations in the genes but from changes in the normal activation or
expression of certain genes.
Problems also may result from programming errors in the genetic material from a
donor cell. When an embryo is created from the union of a sperm and an egg, the
embryo receives copies of most genes from both parents. A process called
"imprinting" chemically marks the DNA from the mother and father so that only one
copy of a gene (either the maternal or paternal gene) is turned on. Defects in the
genetic imprint of DNA from a single donor cell may lead to some of the
developmental abnormalities of cloned embryos.
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Should humans be cloned?
Due to the inefficiency of animal cloning (only about 1 or 2 viable offspring for
every 100 experiments) and the lack of understanding about reproductive
cloning, many scientists and physicians strongly believe that it would be
unethical to attempt to clone humans. Not only do most attempts to clone
mammals fail, about 30% of clones born alive are affected with "large-offspringsyndrome" and other debilitating conditions. Several cloned animals have died
prematurely from infections and other complications. The same problems
would be expected in human cloning. In addition, scientists do not know how
cloning could impact mental development. While factors such as intellect and
mood may not be as important for a cow or a mouse, they are crucial for the
development of healthy humans. With so many unknowns concerning
reproductive cloning, the attempt to clone humans at this time is considered
potentially dangerous and ethically irresponsible.
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Applications of Gene Cloning
The process of gene cloning can be used for producing eukaryotic proteins inthe bacterial cells, and for establishing a gene library. Following are some of
the fields where gene cloning has found its application.
Medical Utility
In medicine, bacteria play a vital role for the synthesis or production of many
vitamins, hormones and antibiotics. It is done by introducing the desired geneinto the plasmid and then this plasmid replicates to make multiple copies of this
gene. If scientists have to treat some dangerous disease, they clone the healthy
gene and then insert it into the organism to replace it with the diseased gene.
The ability to clone a gene is not only valuable for conducting biological
research. Many important pharmaceutical drugs and industrial enzymes are
produced from cloned genes. For example, insulin, clotting factors, human
growth hormone, cytokines (cell growth stimulants), and several anticancerdrugs in use are produced from cloned genes
Agricultural Utility
Bacteria also are important for the nitrogen fixation. Bacteria along with the
desired gene are used to increase the crop productivity and health. They make
the farmers free of using expensive fertilizers which can damage the crops.
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Conclusion
Gene cloning is the replication of DNA fragments by the use of a self-replicating
genetic material. Gene cloning duplicates only individual genes of an
organism's DNA.
Deoxyribonucleic acid, or DNA, is the genetic material contained within all
organisms.
Specific genes are isolated on the DNA molecule for cloning through the use of
restrictive enzymes.
Plasmids are the self-replicating genetic material that actually duplicates the
host DNA fragment. Plasmids are biologically engineered to be compatible with
the host DNA fragment.
Cloningdoes not introduce new genes into a population so will not increase
genetic diversity. Cloning of domesticated animals could be important in the
future production oftransgenic livestock.
Cloning may have uses inpreserving endangered species and may become a
viable tool forreviving extinct species.
http://en.wikipedia.org/wiki/Genetic_diversityhttp://en.wikipedia.org/wiki/Genetically_modified_organismhttp://en.wikipedia.org/wiki/Extinctionhttp://en.wikipedia.org/wiki/Extinctionhttp://en.wikipedia.org/wiki/Extinctionhttp://en.wikipedia.org/wiki/Genetically_modified_organismhttp://en.wikipedia.org/wiki/Genetic_diversity -
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References
www.google.com
www.ornl.gov.in
www.wikipedia.org
www.ehow.com
www.medicine.jrank.org
www.lukashensel.de.com
www.biotech.about.com
www.ncbi.nlm.nih.gov
www.tutorvista.com
www.departments.weber.edu
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