The sea anemone undergoing cloning thumb]]
In biology, cloning is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments, cells, or organisms. The term also refers to the production of multiple copies of a product such as digital media or software. The term clone is derived from the Ancient Greek word κλών, referring to the process whereby a new plant can be created from a twig. In horticulture, the spelling clon was used until the twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o". Since the term entered the popular lexicon in a more general context, the spelling clone has been used exclusively. In botany, the term lusus was traditionally used.
In the United States, the human consumption of meat and other products from cloned animals was approved by the FDA on December 28, 2006, with no special labeling required because food from cloned organisms has been found to be identical to the organisms from which they were cloned. Such practice has met strong resistance in other regions due to misinformation, # fragmentation - breaking apart a strand of DNA
# ligation - gluing together pieces of DNA in a desired sequence # transfection - inserting the newly formed pieces of DNA into cells # screening/selection - selecting out the cells that were successfully transfected with the new DNA Although these steps are invariable among cloning procedures a number of alternative routes can be selected, these are summarized as a cloning strategy. Initially, the DNA of interest needs to be isolated to provide a DNA segment of suitable size. Subsequently, a ligation procedure is used where the amplified fragment is inserted into a vector . The vector is linearised using 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. A number of alternative techniques are available, such as chemical sensitivation of cells, electroporation, optical injection and biolistics. Finally, the transfected cells are cultured. As the aforementioned procedures are of particularly low efficiency, there is a need to identify the cells that have been successfully transfected with the vector construct containing the desired insertion sequence in the required orientation. 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 colour selection markers, which provide blue/white screening 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 must be required to confirm that cloning was successful. This may be accomplished by means of PCR, restriction fragment analysis and/or DNA sequencing. Cell cloning
Cloning unicellular organisms
Cloning a cell means to derive a population of cells from a single cell. In the case of unicellular organisms such as bacteria and yeast, this process is remarkably simple and essentially only requires the inoculation of the appropriate medium. However, in the case of cell cultures from multi-cellular organisms, cell cloning is an arduous task as these cells will not readily grow in standard media. A useful tissue culture technique used to clone distinct lineages of cell lines involves the use of cloning rings . According to this technique, a single-cell suspension of cells that 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 clonal...
References: External links
from Human Genome Project Information website.
Freeview video by the Vega Science Trust and the BBC/OU
, an accessible and comprehensive look at cloning research from the University of Utah 's Genetic Science Learning Center
. Try it yourself in the virtual mouse cloning laboratory, from the University of Utah 's Genetic Science Learning Center
The National Review, July 15, 2002 8:45am
Please join StudyMode to read the full document