Cloning

• Cloning

  The process of making a clone, a genetically identical copy of an organism by replacing the nucleus of an unfertilized ovum with the nucleus of a body cell from the organism
• How cloning differs from natural production

  • Humans and most organisms result from sexual production, obtaining half their genes from the mother's egg and half from the father's sperm
  • In cloning, the egg nucleus is removed and replaced with a donor's nucleus, containing only the donor's genes
• History of cloning

  1. 1894: Hans Dreisch cloned a sea urchin

  2. 1902: Dr. Hans Spemann cloned salamander embryos

  3. 1958: Steward cloned a carrot

  4. 1984: Steen Willadsen cloned sheep and cows

  5. 1996: Dolly the sheep cloned from an adult cell

  6. After Dolly, many other animals cloned
• Types of cloning

  • DNA/Gene cloning
  • Reproductive cloning
  • Therapeutic cloning
• DNA/Gene cloning


  A collection of DNA fragments derived from the genome of an organism and cloned randomly into suitable cloning vectors
• Reproductive cloning


  The production of a genetic duplicate of an existing organism
• How to generate a Dolly

  1. Step 1: Udder cells taken from donor sheep

  2. Step 2: Unfertilized egg cell with nucleus removed

  3. Step 3: Donor cell fused with egg cell using electricity

  4. Step 4: Embryo implanted into surrogate mother

  5. Step 5: Surrogate mother gives birth to Dolly
• Reproductive cloning: risks and benefits

  • Benefits: Maintain good DNA, clone genetically modified animals
  • Risks: Highly inefficient, die mysteriously, morally wrong to experiment on animals, could lead to human cloning
• Therapeutic cloning: risk and benefits

  • Benefits: Produce organs from cloned stem cells, produce healthy cells for transplantation, reduce need for organ donors, test drugs
  • Risks: Killing embryos in the process
• Human cloning


  The concept of making genetically identical copies of humans to remove genetic disorders
• Process of human cloning

  1. Donor egg

  2. Remove nucleus

  3. Remove cells from person to be cloned

  4. Human egg donor

  5. Surrogate mother

  6. Implant embryo into surrogate mother

  7. Fuse cell and enucleated egg with electricity
• Animal cloning

  • Pet cloning started in 1997, first cloned cat born in 2001
  • Biopsy taken from live or recently deceased animal, cells grown and preserved
  • Cells treated to prevent assignment to particular function
  • Genetic material removed from eggs, eggs and cells fused by electricity to create cloned embryos
  • Cloned embryos implanted into female animals during induced reproductive cycle
• Advantages of cloning

  • Endless supply of animals to clone
  • never run out of food from animals
  • scientist can clone organs and help people live long
  • clone body parts, cloned animals are safe to eat
• Disadvantages of cloning

  • Inhumane, against religious beliefs, cloned animals often born deformed
  • pets that are cloned often don't look the same
• Cloning can be good or bad
• Risks of cloning

  • Expensive and highly inefficient, more than 90% of attempts fail
  • Cloned animals have compromised immune function and higher rates of infection, tumour growth, and other disorders
  • Clones often die mysteriously
  • appearing healthy at a young age
• Applications of cloning

  • Biomedical research
  • Animals as drug producers
  • Animal models
  • Breeding and regenerating body tissue
  • Xenotransplantation
  • Livestock breeding and agriculture
  • Transgenic clones
  • Changes to agricultural structures
• According to the FDA, meat and milk from cow, pig, and goat clones, and their offspring, are as safe as food we eat every day
• The main use of clones is to produce breeding stock, not food
• Therapeutic cloning- creates embryonic stem cell and was hoped to grow healthy tissue to replace injured tissue in the human body
• Dna/Gene cloning - refers to an individual carrying a cloning vector
• cloning vectors: plasmids and phages
• the egg nucleus is removed through a microscopic laboratory procedure and replaced with a donor's nucleus, containing the unique genes of that individual
• the cloned organism is a near genetic copy of its sole parents rather that a random genetic combination of two parents
• the embryo's genetic structure is located in chromosomes found in nucleus of every embryonic cell
• the hew organism obtains one half of its genes from the mothers egg and the other half from the father's sperm
• Xenotransplantation - (avoid tissue rejections) insulin producers