Cloning

What is the process of micropropagation?

Parent plant is chosen with desired characteristics (must be disease-free)

1. A small part of the growing tip is removed, because it has actively dividing cells (explant)

2. Growing tip is sterilised (with SDICN / Milton solution), to kill any bacteria or fungi

3. Growing tip is cut into many pieces to make many plants

4. It’s grown in vitro: put into plates of sterile agar jelly (this provides an ideal growing medium for the plant) with lots

   of nutrients and growth hormones (that stimulate plant cells to rapidly divide)

5. Cells divide and grow into small plants called plantlets

6. Small plants taken out of medium, planted into soil and put into glasshouse

What are the advantages and disadvantages of micropropagation?

Advantages:

• Produces a large quantity of plants very quickly.

• Can grow plants all year round.

• Can grow rare or endangered plants to increase the populations.

• New plants grown in sterile conditions so pest and disease free.

• Genetic modifications can be introduced to a large number of plants.

• Little space is needed to grow them.

Disadvantages:

• All offspring identical so vulnerable to the same diseases.

• Requires sterile lab facilities.

• Vulnerable to pests.

What are the stages in the production of cloned mammals?

1. The diploid nucleus is taken from an adult cell.

2. An enucleated egg cell is prepared from another female of the same species.

3. The nucleus is placed in the empty egg. 

4. An electric shock is given that stimulates the new fused cell to divide.

5. The embryo is placed in the uterus of a surrogate mother.

6. A fetus develops that is identical to the original adult animal.

How can cloned transgenic animals can be used to produce human proteins?

Sheep have been genetically modified to produce several human proteins.

One of these is a protein which is used to treat conditions such as emphysema and cystic fibrosis.

Genetically modified sheep secrete the protein in their milk.

Cloning sheep like these would allow production of much more of this valuable protein.