Cloning in Plants and Animals

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Reproductive cloning is the production of offspring which are genetically identical to either the mother (nuclear transfer), or the other offspring (splitting embryos). 
Non-reproductive cloning is the use of stem cells in order to generate replacement cells, tissues or organs which may be used to treat particular diseases or conditions of humans.

Molecular evidence has shown that all specimens of the English Elm tree, Ulmus procera, form a genetically isolated clone. Although English Elm trees make pollen, they rarely produce seeds. Instead they spread by developed structures known as ****ers from their roots. Each **** can grow into a new tree. This tendancy of elms to create ****ers has been exploited by humans, who have separated the ****ers, with roots attached, and used them to plant hedges and establish neww woodlands.
The English Elm clone is genetically isolated from other varieties of elm because they do not produce seeds and they only reproduce asexually.
The production of ****ers is an example of vegetative propagation.
A new, virulent strain of elm disease fungus killed 25 million English Elm trees, almost the entire population, after it was introduced on imported timber. Beetles that lived under the bark of elm trees spread the fungus. The saws used to cut down dead branches were not sterilised after use. When the saws were used to prune healthy trees, these trees became infected also.
This happened because they were all susceptible to this disease as, being clones, they are genetically identical. The beetles fly from tree to tree acting as a vector and as the trees grow close together and the disease also spreads through the ****ers it spreads rapidly. 
When the tree dies, the ****ers grow into new trees around the base of the dead trunk, called a…


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