
C l o n i n g i s t h e p r o c e s s o f c r e a t i n g a n i d e n t i c a l c o p y o f a n o r i g i n a l o r g a n i s m o r t h i n g . A c l o n e i n t h e b i o l o g i c a l s e n s e , t h e r e f o r e , i s a s i n g l e c e l l ( l i k e b a c t e r i a , l y m p h o c y t e s e t c . ) o r m u l t i - c e l l u l a r o r g a n i s m t h a t h a s b e e n d i r e c t l y c o p i e d f r o m , a n d i s t h e r e f o r e g e n e t i c a l l y i d e n t i c a l t o , a n o t h e r l i v i n g o r g a n i s m . S o m e t i m e s t h i s t e r m c a n r e f e r t o " n a t u r a l " c l o n e s m a d e e i t h e r w h e n a n o r g a n i s m r e p r o d u c e s a s e x u a l l y o r w h e n t w o g e n e t i c a l l y i d e n t i c a l i n d i v i d u a l s a r e p r o d u c e d b y c h a n c e ( a s w i t h i d e n t i c a l t w i n s ) , b u t i n c o m m o n p a r l a n c e , a c l o n e i s a n i d e n t i c a l c o p y c r e a t e d i n t e n t i o n a l l y .
T h e t e r m c l o n e i s d e r i v e d f r o m t h e G r e e k w o r d f o r " t w i g " . I n h o r t i c u l t u r e , t h e s p e l l i n g c l o n w a s u s e d u n t i l t h e t w e n t i e t h c e n t u r y ; t h e f i n a l e c a m e i n t o u s e t o i n d i c a t e t h e v o w e l i s a " l o n g o " i n s t e a d o f a " s h o r t o " . S i n c e t h e t e r m e n t e r e d t h e p o p u l a r l e x i c o n i n a m o r e g e n e r a l c o n t e x t , t h e s p e l l i n g c l o n e h a s b e e n u s e d e x c l u s i v e l y .
Human cloning is the creation of a genetically identical copy of an existing, or previously existing human or 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.
Therapeutic cloning is the procedure for creating stem cells genetically compatible with the patient. Therapeutic cloning might provide a way to grow organs in host carrier, which become completely compatible with the original. Host carrier growing poses a risk of trans-species diseases if the host is of a different species (e.g., a pig). In human beings, this is a highly controversial issue, as it involves creating human embryos in vitro and then destroying them to obtain multipotent embryonic stem cells.
Molecular cloning refers to the procedure whereby a DNA sequence is amplified by genetic engineering techniques. 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. In practice, localization of the gene does not always enable one to amplify the relevant genomic sequence.