DNA Cloning Lesson

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Page 1: DNA Cloning Lesson

DNA Cloning

Group 3

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*Cloning: Reproducing genetically identical copies of DNA, Cells organisms through some asexual means.

*To "clone a gene" is to make many copies of it – forexample, by replicating it in a culture of bacteria.

*Duplicating a person e.g. identical twins is called “Reproductive” cloning.

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*Duplicating part of a person e.g. a heart or liver,or even just a few cells is called “Therapeutic”cloning (gene therapy).

*Cloned gene can be a normal copy of a gene or acloned gene can be an altered version of a gene.

*Otherwise, the organisms are called transgenic organisms – these organisms today are used toproduce products desired by humans.

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Cloning an organism

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Cloning a human gene

* Scientists can use two procedures to clone DNA.

A. Recombinant DNA (rDNA) B. Polymerase chain reaction


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A. Recombinant DNA (rDNA) Recombinant DNA technology is used to produce large quantity of insulin.

Recombinant: The creation of new combinations of DNA segments that is not found together in


THE PROCESS OF rDNA: Isolate DNA Cut with restriction enzymes Ligate into cloning vector transform recombinant DNA molecule into host cell each transformed cell will divide many, many times to form a colony of millions of cells, each of which carries the recombinant DNA molecule (DNA clone)

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1. DNA that codes for the production of insulin is removed from the chromosome of a human pancreatic cell.

2. Restriction enzymes cut the gene from the chromosome (isolating the gene for insulin)

3. A plasmid (acting as a vector/carrier of new gene) is removed from the bacterium and cut open with a restriction enzyme to form sticky ends.

4. Ligase (enzyme) is added to join the insulin gene to the plasmid of the bacterium cell - forming recombinant DNA.

5. The recombinant DNA can then be reinserted into the bacterium, the bacterium will then produce more insulin, therefore cloning the gene.

6. When the bacterium reproduces it makes the insulin inserted into the plasmid.

7. The bacteria are kept in huge tenks with optimum pH, temperature and nutrient values, where they multiply rapidly, producing enormous amounts of insulin, this is then purified and sold.

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B. Polymerase chain reaction (PCR) •PCR – Used in genetic profiling.

•To solve crimes – criminals usually leaveDNA evidence at the scene of the crime in the form of saliva, blood, skin, semen and hair.

•These all contain DNA. If only a little bit of DNA is found or the DNA is old, we can make copies of the available DNA by means of PCR.

*From the DNA produced through PCR, DNA fingerprint can be generated.

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PCR METHOD1. Sample containing DNA is heated in a test tube to separate DNA into single strands.2. Free nucleotides are added to the test tube with DNA polymerase (enzyme), to allow DNA replication.3. DNA is cooled to allow free nucleotides to form a complementary strand along side each single strand.4. In this way the DNA is doubled giving sufficient amount of DNA to work with.

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• Recombinant DNA is used to make transgenic bacteria.

• They are used to make insulin, clotting factor VIII, human growth hormone and hepatitis B vaccine.

• Transgenic bacteria is used to protect the roots of plants from insect attack, by producing insect toxins.

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• Example = pomato• Genetically modified to produce potato's

below the ground and tomato's above the ground.

• Foreign genes transferred to cotton, corn, and potato strains have made these plants resistant to pests because their cells now produce an insect toxin.