what are the four main types of cloning?

Question

like i think theres...

-reproductive
-stem cell (not so sure bout that one)

Answer 1

There's only 3.

Recombinant DNA cloning (DNA cloning)
Therapeutic Cloning (your stem cell cloning)
Reproductive Cloning

Answer 2

There are three types: (1) DNA cloning, (2) reproductive cloning, (3) therapeutic cloning. ~A~

Answer 3

Molecular cloning
Molecular cloning refers to the procedure of isolating a DNA sequence of interest and obtaining multiple copies of it in an organism. Cloning is frequently employed to amplify DNA fragments containing genes, an essential step in their subsequent analysis. Frequently, the term cloning is misleadingly used to refer to the identification of the chromosomal location of a gene associated with a particular phenotype of interest, such as in positional cloning. In practice, localisation of the gene to a chromosome or genomic region does not necessarily enable one to isolate or amplify the relevant genomic sequence.

Cloning of any DNA sequence involves the following four steps: fragmentation, ligation, transfection, and screening/selection. Initially, the DNA of interest needs to be fragmented to provide a relevant DNA segment of suitable size. Preparation of DNA fragments for cloning is frequently achieved by means of PCR, but it may also be accomplished by restriction enzyme digestion and sometimes fractionation by gel electrophoresis. Subsequently, a ligation procedure is employed whereby the amplified fragment is inserted into a vector. The vector (which is frequently circular) is linearised by means of restriction enzymes, and incubated with the fragment of interest under appropriate conditions with an enzyme called DNA ligase. Following ligation the vector with the insert of interest is transfected into cells. Most commonly electroporation is employed, although a number of alternative techniques are available, such as chemical sensitivation of cells. Finally, the transfected cells are cultured. As the aforementioned procedures are of particularly low efficiency, there is need to identify the cell colonies that have been successfully transfected with the vector construct containing the desired insertion sequence. Modern cloning vectors include selectable antibiotic resistance markers, which allow only cells in which the vector has been transfected, to grow. Additionally, the cloning vectors may contain color selection markers which provide blue/white screening (α-factor complimentation) on X-gal medium. Nevertheless, these selection steps do not absolutely guarantee that the DNA insert is present in the cells obtained. Further investigation of the resulting colonies is required to confirm that cloning was successful. This may be accomplished by means of PCR, restriction fragment analysis and DNA sequencing.

Genetic cloning
Cloning a cell means to derive a (clonal) population of cells from a single cell. This is an important in vitro procedure when the expansion of a single cell with certain characteristics is desired, for example in the production of gene-targeted ES cells. A valuable tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings (cylinders). According to this technique, a single-cell suspension of cells which have been exposed to a mutagenic agent or drug used to drive selection is plated at high dilution to create isolated colonies; each arising from a single and potentially clonally distinct cell. At an early 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 of trypsin is added. Cloned cells are collected from inside the ring and transferred to a new vessel for further growth.

Most individuals began as a single cell and are therefore the result of clonal expansion in vivo.

Reproductive Cloning
Reproductive cloning is a technology used to generate an animal that has the same nuclear DNA as another currently or previously existing animal. Dolly the sheep, was created by reproductive cloning technology. In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic material, has been removed. The reconstructed egg containing the DNA from a donor cell must be treated with chemicals or electric current in order to stimulate cell division. Once the cloned embryo reaches a suitable stage, it is transferred to the uterus of a female host where it continues to develop until birth.

Dolly or any other animal created using nuclear transfer technology is not truly an identical clone of the donor animal. Only the clone's chromosomal or nuclear DNA is the same as the donor. Some of the clone's genetic materials come from the mitochondria in the cytoplasm of the enucleated egg. Mitochondria, which are organelles that serve as power sources to the cell, contain their own short segments of DNA, although this is only 0.01% of the total DNA. Acquired mutations in mitochondrial DNA are believed to play an important role in the aging process.

Also mutations occur with every cell division so no two cells in an individual are identical, nor are clones. Thus, nuclear transfer clones from different maternal lineages are not clones in the strictest sense because the mitochondrial genome is not the same as that of the nucleus donor cell from which it was produced. This may have important implications for cross-species nuclear transfer in which nuclear-mitochondrial incompatibilities may lead to inviability.

Human cloning
Human cloning is the creation of a genetically identical copy of an existing, or previously existing human, by growing cloned tissue from that individual. The term is generally used to refer to artificial human cloning; human clones in the form of identical twins are commonplace, with their cloning occurring during the natural process of reproduction.

Human cloning is amongst the most controversial forms of the practice. There have been numerous demands for all progress in the human cloning field to be halted. One of the most ethically questionable problems with human cloning is farming of organs from clones. For example, many believe it is unethical to use a human clone to save the life of another. In this scenario, the cloned human would be euthanized so that the vital organs could be harvested. This process of renewing the body's organs would potentially increase the life expectancy of a human by 50 years.

The cloning described above is reproductive cloning, not to be confused with research cloning in which only parts (such as an organ) are cloned using genetic material from a patient's tissues.

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