Adapted from www.genome.gov
What is cloning?
• Cloning is a process that produces genetically
identical genes, cells, tissues and organisms.
Naturally Occurring Clones
Some plants and bacteria produce clones
through asexual reproduction.
Natural human clones are known as identical
twins. The twins are produced when an embryo
splits, creating two or more embryos that have
almost identical DNA.
3 Types of Artificial Cloning
• 1. Gene cloning – produces copies of genes or
segments of DNA.
• 2. Reproductive cloning produces copies of
whole animals (human cloning is illegal).
• 3. Therapeutic cloning produces stem cells for
experiments aimed at creating new tissues to
replace injured or diseased tissues.
Artificial Embryo Twinning
1.Embryo is purposefully split in half.
2.Two identical embryos grow in the mother.
3.Identical twins are born.
• Scientists remove a cell (like a skin cell) from the
animal they want to copy.
• They remove the nucleus of an egg cell from the
surrogate mother ( the female who will grow and
birth the clone).
• They put the DNA from the skin cell into the egg
cell of the surrogate mother.
• A few months later, the clone is born (as a baby).
Dolly the Sheep
1.DNA from sheep X is removed from sheep X’s
2.The nucleus from Sheep Y’s egg cell is removed.
3.Sheep X’s DNA is placed into sheep Y’s egg cell.
4.Scientist shock the egg cell to trick it into thinking
it’s a normal cell.
5.The egg cell starts acting like a normal cell and
dividing like an embryo.
6.Sheep Y gives birth to Dolly the clone – who has
Sheep X’s DNA.