The Production of Cloned Mammals (Edexcel IGCSE Biology): Revision Note

Cloning Mammals

Adult cell cloning

• Adult cell cloning is achieved in the following way:

  • The nucleus is removed from an unfertilised egg cell, producing an enucleated egg cell

  • The diploid nucleus from a mature adult body cell, such as a skin cell, is inserted into the enucleated egg cell

  • A very small electric shock stimulates the cell to divide (by mitosis) to form an embryo

  • These embryo cells contain the same genetic information as the adult skin cell

  • When the embryo has developed into a ball of cells, it is inserted into the uterus of an adult female (known as the surrogate mother) to continue its development until birth

• This process was used to create the first clone (exact genetic copy) of a mammal in 1996

  • Scientists in Scotland successfully cloned an adult female sheep

  • The clone was called Dolly

Adult cell cloning: the cloning technique used to produce the first cloned mammal, Dolly the sheep

Benefits & risks of cloning table

Cloning to Produce Human Proteins

• Dolly the sheep was the first cloned mammal produced from an adult cell

• Scientists can produce transgenic animals by inserting a foreign gene into their genome

• The foreign gene can code for a useful protein, which the animal can then produce in its milk, eggs, or blood

• Once a transgenic animal has been created, it can be cloned to produce more animals with the same trait

• Uses of transgenic animals include producing useful proteins for medical purposes, such as proteins to treat diseases in humans