Cloning

• outline the differences between reproductive and non-reproductive cloning;

• describe the production of natural clones in plants using the example of vegetative propagation in elm trees;

• describe the production of artificial clones of plants from tissue culture;

• discuss the advantages and disadvantages of plant cloning in agriculture (HSW6a, 6b, 7c);

• describe how artificial clones of animals can be produced; • discuss the advantages and disadvantages of cloning animals

(HSW4, 6a, 6b, 7c).

Outline the differences between reproductive and non-reproductive cloning

Cloning = the production of genetically identical individualsReproductive Cloning = Using cloning to produce whole animalsNon-Reproductive Cloning = Using cloning to produce cells

Cells divide by binary fission, which means that they copy and split into twoNon reproductive cloning in humans was first done in 1951 from cancer cells from a patient who died- this was done without the patient’s permission which would be illegal nowadays Now there are thousands of cells grown all over the worldThey can be used to test potential drugs or can be used in DNA analysis to investigate genetic diseasesStem cells can now also be used which are non-differentiated (they are not specialised) They are said to be totipotent (can form any type of cell) or pluripotent (can form most types of cell)There is some debate over stem cells as the best source are from embryos

Describe the production of natural clones in plants using the example of vegetative propagation in elm trees

Plants can clone themselves naturally by asexual reproduction, this is also known as vegetative propagationBarring mutation, vegetative propagation produces genetically identical plants

Elm Trees: suckering occurs when trees are coppiced (chopped down a bit)- roots form new shoots (called suckers or basal sprouts) that are genetically identical and sprout up in a ring around the tree known as a clonal patch. As they are identical they also suffer from the American Fungus that can kill the ‘parent plant’

describe the production of artificial clones of plants from tissue culture

• Normally plants are cloned using their own natural method e.g. strawberry plants making runners, potatoes from tubers etc.

• Gardeners and commercial growers use tissue cultures

Tissue Culture1. Remove cells that are able to divide by mitosis (meristematic cells) from a

plant2. This is now called an explant3. This must be done aseptically so no contamination occurs4. Immerse it in plant growth substances (auxin and cytokinin) also containing

sucrose, potassium, magnesium etc.5. Undifferentiated cells divide to form a callus6. Callus divided and placed on agar with growth substances7. Plants then removed and planted

discuss the advantages and disadvantages of plant cloning in agriculture

Advantages:• All plants genetically identical• Plants will mature at the same time and be harvested at

the same time• Plants can be grown out of season

Disadvantages:• Arrival of new pathogen or climate change will affect all

clones• High costs involved

describe how artificial clones of animals can be produced

• Nuclear transfer: skin cell taken, nucleus removed, inserted into an empty egg cell, transferred into a surrogate. The offspring is a clone of the nucleus donor

• Splitting Embryos: fertilisation happens normally, ball of cells split up and transplanted into many surrogates. The offspring are clones of each other but not of the parents

discuss the advantages and disadvantages of cloning animals

Advantages• Same genetic informationDisadvantages• short life span