IBDP Biology - Cloning Animals

In this IBDP Biology topic, you can learn about cloning animals.

• Cells from a developing embryo can be separated
• Each then going onto producing genetically identical organisms. 
• It has been used to clone sheep, cattle, rabbits and toads.

• A differentiated cell can be taken and its nucleus placed in an egg cell which has had its own nucleus removed. The cell is an enucleated. 
• The first animal cloned by this method was a sheep called Dolly (in honour of Dolly Parton). 
• The cell was taken from a mammary gland in a 6- year-old ewe (female sheep), its nucleus transplanted into a cell from a second sheep and the inserted into the uterus of a third sheep, and then a fourth to develop. This was the only success out of 277 attempts

This is all about using cloned cells to generate cells, tissues and organs to replace those which have been damaged by disease or accidents.

• Regeneration of heart muscles following a heart attack.
• Regeneration of nervous tissue from diseases such as multiple sclerosis.
• Repairing the spinal cord of those who have been paralysed by an accident that caused a broken back or neck.

1. By having genetically identical cells to an individual the body will not reject them because they will not be recognised as foreign.
2. Could stop the issues of waiting for donor organs to become available.
3. Cloned cells can be used to generate any cell type because they are totipotent. Damage that has been caused by some diseases cannot be currently fixed by transplant and other treatments.

1. High-valued animals can be cloned in large numbers for example cows having a high milk yield.
2. Rare animals can be cloned to preserve the species.
3. Genetically modified animals can be reproduced for example sheep that produce pharmaceutical chemicals in their milk.

1. High-valued animals not reproduced with their welfare in mind. For example some chickens that have been developed are unable to walk.
2. They have limited genetic variation so are unable to cope with changes in the environment.
3. Unsure whether cloning will make animals die prematurely. For example Dolly the sheep was put down, age 6 after suffering from a type of lung cancer due to a virus. Post-mortem found no irregularities for a sheep of her age.

This is the end of the topic

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Drafted by Eva (Biology)

Photo references:

1. https://www.csus.edu/indiv/g/gaskilld/socialissues14/cloning.htm
2. https://alevelbiologystudent.weebly.com/223-cloning-animals.html
3. https://www.farmonline.com.au/story/4908346/the-pros-and-cons-of-cloning-beef-animals/