Animal cloning

• Natural animal clones


  • Produced naturally as a result of sexual reproduction
  • Embryo splits during early development and develops into multiple embryos with same genetic information
  • Identical twins are natural clones
• Artificial embryo twinning


  1. Egg cell extracted and fertilised

  2. Fertilised egg left to divide at least once, forming embryo in vitro

  3. Individual cells from embryo separated and each develops into an embryo

  4. Embryos implanted into surrogate mothers
• Somatic cell nuclear transfer (SCNT)

  1. Somatic cell taken from animal A, nucleus extracted

  2. Oocyte taken from animal B, nucleus removed to form enucleated oocyte

  3. Nucleus from animal A inserted into enucleated oocyte

  4. Nucleus and enucleated oocyte fused and stimulated to divide

  5. Embryo implanted into surrogate mother
• Uses of animal cloning

  • Testing new drugs on cloned animals
  • Increasing number of animals with desirable characteristics for breeding
  • Producing genetically modified animals to make beneficial substances
  • Saving endangered species from extinction
• Cloning doesn't have to be used to make whole animals, can use cloned embryonic stem cells
• Arguments for animal cloning

  • Desirable genetic characteristics always passed on
  • Infertile animals can be reproduced
  • Animals can be cloned at any time
  • Increasing endangered species population preserves biodiversity
  • Can help develop new disease treatments
• Arguments against animal cloning

  • Very difficult, time-consuming and expensive
  • No genetic variability, undesirable traits passed on
  • Clones may not live as long as natural offspring
  • Using cloned human embryos for stem cells is controversial
• Dolly the sheep was a clone generated by SCNT, took 277 attempts before successful birth, had shorter lifespan than average for breed