1 of 14© Boardworks Ltd 2011 Cloning. 2 of 14© Boardworks Ltd 2011 Cloning in the media.
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Transcript of 1 of 14© Boardworks Ltd 2011 Cloning. 2 of 14© Boardworks Ltd 2011 Cloning in the media.
1 of 14 © Boardworks Ltd 2011
Cloning
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Cloning in the media
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Asexual reproduction
Cloning is an example of asexual reproduction.
Organisms that reproduce asexually include:
micro-organisms, such as bacteria and yeast
many plants, such as spider plants, strawberries and potatoes, produce bulbs or runners for asexual reproduction
some insects, such as aphids.
In asexual reproduction, a single organism makes a copy of itself with exactly the same genetic code. There is no fusing of gametes or mixing of genetic information, and so no variation occurs. The new organism is a clone of the original.
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Human clones already exist! Identical twins have exactly the same genes and are therefore natural clones of each other.
Human clones
Identical twins are created when a fertilized egg splits in two, creating two separate but genetically-identical embryos.
+ +=Any differences between identical twins, or other clones, are due to environmental factors not genetics.
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Cloning techniques
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Cloning an adult
Cloning a single adult animal, especially a mammal, is very complicated.
The most famous animal clone is Dolly the sheep, who was born on 5th July 1996.
Dolly was not the first animal clone, but the first mammal to be cloned from an adult cell.
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What is nuclear transfer?
Dolly was created using a technique called nuclear transfer.
An electric shock makes the egg cell divide and develop like a normal fertilized egg. The important difference is that it only contains the DNA from one, rather than two, animals.
In this technique, the nucleus (i.e. DNA) from a body cell of the adult (a somatic cell) is removed.
This nucleus is then inserted into an egg cell that has had its own nucleus removed.
Why couldn’t the DNA be taken from a sperm or egg cell?Because they only contain half the genes of the animal.
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How was Dolly created?
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Advantages and disadvantages
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Opinions on human cloning
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Summary activities
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Glossary
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Anagrams
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Multiple-choice quiz
