cloning

• how does micropropagation take place for cloning?

  • plant with desirable characteristics selected to be cloned - explants are taken off from tip of stems and sides of shoots of the plants
  • explants are sterilised to kill any microorganisms
  • explants grown in vitro - placed in petri dish containing a nutrient medium - medium has all the nutrients the explant needs to grow - also contains growth hormones
  • cells in explants divide and grow into a small plant - large quantities of plants are required - further explants can be taken from these small plants - so on until enough small plants are produced
  • the small plants taken out of the medium - planted in soil and put into glasshouses - develop into plants that are genetically identical to original plant - share same characteristics
• how does cloning an adult mammal work?

  • first mammal to be cloned successfully from mature cell - Dolly the sheep
  • the nucleus of the sheep's egg removed - creating an enucleated cell
  • a diploid nucleus was inserted in its place - this was a nuclues from a mature udder cell of a different sheep
  • cell stimulated so starts to divide by mitosis as if it was a normal fertilised egg
  • dividing cell implanted into uterus of another sheep to develop until it was ready to be born
  • the result - Dolly - a clone o the sheep that the udder cell came from
• how can cloned transgenic animals used to produce human proteins?

  • cows, sheep make protein naturally in their milk - by transferring human genes into cells of these animals - will make them produce useful human proteins in their milk
  • they can produce human antibodies - used in therapy for illnesses - arthuritis - some types of cancers and multiple sclerosis
  • transgenic chickens - engineered to produce human proteins in egg white
  • these transgenic animals can then be cloned - so that useful genetic characteristics are passed on which don't always take place with breeding