Cloning — AQA GCSE Biology (Separate)

Cloning produces genetically identical organisms. There are several methods used in plants and animals.

Plant cloning

• Cuttings — an older, simple method. A piece of a plant (with a bud) is cut off and planted; it grows into a genetically identical plant. Used by gardeners to produce many copies of a favourite plant cheaply.
• Tissue culture — small groups of cells from a plant are grown on a nutrient medium with hormones. This produces many identical plants from a tiny amount of tissue. It is used to preserve rare plants and to produce plants commercially.

Animal cloning

• Embryo transplants — an embryo is split into many cells before the cells differentiate. Each cell grows into a genetically identical animal, which can be implanted into host mothers.
• Adult cell cloning:
  1. The nucleus is removed from an unfertilised egg cell.
  2. The nucleus from an adult body cell is inserted into the empty egg cell.
  3. An electric shock stimulates the egg to divide to form an embryo.
  4. The embryo is inserted into the womb of an adult female to develop. (This is how Dolly the sheep was cloned.)

Benefits and concerns

• Benefits: producing many identical organisms with desired features; preserving endangered species; potential medical uses.
• Concerns: reduced variation (gene pool), ethical issues, and uncertainty about the health of clones.

Exam tips

• Learn plant methods (cuttings, tissue culture) and animal methods (embryo transplants, adult cell cloning).
• Be able to put the steps of adult cell cloning in order.
• Clones are genetically identical.
• Note the concern of reduced variation.