How exactly does one go about making an exact genetic copy of an organism? There are 3 methods of cloning: recombinant DNA technology (DNA cloning), reproductive cloning, and therapeutic cloning (Cloning).
- Therapeutic Cloning – Produces a cloned embryo to create embryonic stem cells for understanding and developing treatments
- Reproductive Cloning – Produces copies of whole animals
- DNA Cloning – Produces copies of genes or segments of DNA
Therapeutic Cloning- Produces a cloned embryo to create embryonic stem cells for understanding and developing treatments
Therapeutic cloning involves creating a cloned embryo for the sole purpose of producing embryonic stem cells with the same DNA as the donor cell.
These stem cells can be used in experiments aimed at understanding disease and developing new treatments for disease.
For example, the nucleus of a cell, typically a skin cell, is inserted into a fertilized egg whose nucleus has been removed. The nucleated egg begins to divide repeatedly to form a blastocyst. Scientists then extract stem cells from the blastocyst and use them to grow cells that are a perfect genetic match for the patient. The cells created via therapeutic cloning can then be transplanted into the patient to treat a disease from which the patient suffers.
Scientists hope to use these embryonic stem cells, which have the unique ability to generate virtually all types of cells in an organism, to grow tissues in the laboratory that can be used to grow healthy tissue to replace injured or diseased tissues. In addition, it may be possible to learn more about the molecular causes of disease by studying embryonic stem cell lines from cloned embryos derived from the cells of animals or humans with different diseases.
Reproductive Cloning – Produces copies of whole animals
In reproductive cloning, researchers remove a mature somatic cell, such as a skin cell or an udder cell, from an animal that they wish to copy. A somatic cell is any cell in the body other than the two types of reproductive cells, sperm and egg. Sperm and egg are also called germ cells. In mammals, every somatic cell has two complete sets of chromosomes, whereas the germ cells only have one complete set.
They then transfer the DNA of the donor animal’s somatic cell into an egg cell, or oocyte, that has had its own DNA-containing nucleus removed.
Researchers can add the DNA from the somatic cell to the empty egg in two different ways. In the first method, they remove the DNA-containing nucleus of the somatic cell and inject it into the empty egg. In the second approach, they use an electrical current to fuse the entire somatic cell with the empty egg.
In both processes, the egg is allowed to develop into an early-stage embryo in the test-tube and then is implanted into the womb of an adult female animal. Ultimately, the adult female gives birth to an animal that has the same genetic make-up as the animal that donated the somatic cell. This young animal is referred to as a clone. Reproductive cloning may require the use of a surrogate mother to allow development of the cloned embryo, as was the case for the most famous cloned organism, Dolly the sheep.
Some of the animals that have been cloned are:-
- Rhesus monkey
DNA Cloning – Produces copies of genes or segments of DNA
DNA cloning is the transfer of a DNA fragment of one organism to a self-replicating genetic element such as a bacterial plasmid. The DNA fragment can be propagated in a foreign host cell. This technology has been around for about 30 years and is commonly used in molecular biology. Gene cloning produces copies of genes or segments of DNA.
Some uses of this technology include:
- Isolation of a particular gene, part of a gene or region of a genome
- Production of a desired RNA or protein molecule in large quantities
- Increased production efficiency for commercially made enzymes and drugs
- Modification of existing organisms so that they show a trait that was not previously encoded in the genome.