Triple Science Only - Animal cloning
Laura Armstrong & Joe Wolfensohn
Teachers
Recall Questions
This topic requires prior knowledge of cloning and reproduction.
What is meant by the term "clone"?
A clone is an organism that is genetically identical to another organism.
Where is DNA found within a cell?
The nucleus.
What is sexual reproduction?
It involves the fusion of gametes (fertilisation), such as an egg and a sperm cell.
Topic Explainer Video
Check out this @JoeDoesBiology video that explains animal cloning, then read the study notes. Once you’ve gone through them, don’t forget to try the practice questions!
What is Animal Cloning?
Animal cloning is the process of producing genetically identical copies of animals.
It uses asexual reproduction techniques to ensure that the offspring have the same DNA as the parent.
1. Embryo Transplants
Step-by-Step Process:
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An egg cell is fertilised by sperm to form a zygote (fertilised egg).
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The zygote divides by mitosis to form an early embryo (a ball of unspecialised cells).
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The embryonic cells are then separated (split apart) before they become specialised.
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Each separated cell is implanted into the uterus of a different host mother.
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Each embryo develops into a genetically identical animal - a clone.
Note- the offspring will be genetically identical to each other, but not to either parent as the initial embryo was made using sexual reproduction.
Uses:
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Produces many identical offspring with desirable traits (e.g. high milk yield, fast growth).
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Used in farming and selective breeding to improve livestock quality.
2. Adult Cell Cloning
Step-by-Step Process:
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The nucleus is removed from an unfertilised egg cell.
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An adult body cell (e.g. a skin cell) is taken from the animal to be cloned.
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The nucleus containing the DNA is removed from the body cell and is inserted into the empty egg cell.
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The cell is given an electric shock to stimulate division, forming an embryo.
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The embryo develops into a ball of cells.
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The embryo is inserted into the uterus of a female host mother, where it continues to develop.
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The resulting offspring is genetically identical to the donor of the adult body cell nucleus.
Note- this type of cloning will produce an animal that is genetically identical to one parent- the parent from which the body cell nucleus was obtained. This nucleus contained all of the DNA of one parent.
Example:
Dolly the Sheep (1996) – the first mammal cloned from an adult body cell.
Adult cell cloning is a type of asexual reproduction-
The nucleus of the egg cell is removed and a nucleus from a body cell is inserted into the empty egg cell. This means only one set of genetic material from one parent is used.
Benefits & Risks of Animal Cloning
|
Benefits |
Risks / Concerns |
|---|---|
|
Produces animals with desirable traits (e.g. high milk yield, disease resistance). |
Reduced genetic variation – all clones are genetically identical and may be killed by the same disease. |
|
Can help save endangered species to prevent extinction. |
Ethical concerns – many cloned embryos fail to develop properly. |
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Can clone animals that produce human medicines in their milk. |
Low success rate and high cost. |
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Useful for scientific research. |
Clones may have shorter life spans or health problems. |
Key Terms
- Clone - An organism that is genetically identical to another organism.
- Asexual reproduction - Reproduction that involves one parent and produces genetically identical offspring.
- Embryo transplant - Splitting an early embryo into separate cells to form identical embryos for implantation.
- Adult cell cloning - Transferring a nucleus from an adult body cell into an empty egg cell to create a clone.
- Nucleus - The part of a cell that contains genetic information (DNA).
No answer provided.
Exam Tip
When asked to describe the process of adult cell cloning, use all steps in order:
nucleus removal from unfertilised egg cell → nucleus transfer from body cell to empty egg cell→ electric shock → embryo development → implantation into uterus.
No answer provided.
Practice Question
Describe how adult cell cloning can be used to produce a clone of an animal. (6 marks)
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The nucleus is removed from an unfertilised egg cell.
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The nucleus from an adult body cell, such as a skin cell, is inserted into the empty egg cell.
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An electric shock is used to stimulate the egg cell to divide.
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This forms an embryo.
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The embryo is then inserted into the uterus of an adult female.
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The offspring that develops is genetically identical to the donor of the adult body cell nucleus.
More Practice
Try to answer these practice questions from the TikTok videos on your own, then watch the videos to see how well you did!