Cloning Animals

Cloning = producing genetically identical animals.

• More complicated than plant cloning.

• Two main methods: embryo transplants and adult cell cloning.

1. Embryo Transplants

• Example: cloning horses (can be applied to any mammal).

• Steps:

  1. Take sperm and egg cells from animals with desired characteristics.

  2. Fertilization → produces a fertilized egg.

  3. Allow fertilized egg to develop into an early-stage embryo.

     • Cells must not have specialized yet.

  4. Use a glass rod to split the embryo into two.

  5. Transplant the two embryos into host mothers.

• Result: offspring are genetically identical clones.

• Limitation: cannot guarantee offspring will have all desired characteristics.

2. Adult Cell Cloning (Somatic Cell Nuclear Transfer)

• Advantage: guarantees clone has the same characteristics as donor adult.

• Example: sheep.

• Steps:

  1. Remove a cell from the adult to be cloned (e.g., skin cell).

  2. Remove nucleus from this cell → contains genetic info.

  3. Take an unfertilized egg cell from same species.

  4. Remove nucleus from egg → now contains no genetic material.

  5. Insert nucleus from adult cell into empty egg.

  6. Give electric shock → egg divides to form an embryo.

  7. Once embryo develops into a ball of cells → insert into host female womb.

• Result: host mother gives birth to a clone.

  • Clone contains none of host mother’s DNA → looks like donor.

✅ Key Takeaways

• Embryo transplant: simpler, but offspring may not have exact traits.

• Adult cell cloning: guarantees traits (as we are cloning from an adult), but more complex.

• Cloning allows scientists to reproduce animals with desired characteristics.