Cloning
Overview
In 1996 a single sheep made headlines around the world. Dolly was the first mammal cloned from an adult body cell, proving that a fully differentiated cell still contains all the genetic information needed to build an entire organism. Cloning - producing genetically identical copies - is not just a laboratory curiosity: it underpins a huge plant propagation industry and opens the door to producing human proteins from animal milk.
This topic covers plant cloning through micropropagation (tissue culture), the stages of adult cell cloning as illustrated by Dolly, and the use of cloned transgenic animals to manufacture valuable human proteins. You will explore the advantages, limitations, and ethical questions surrounding each technique.
Objectives
- Describe the process of micropropagation (tissue culture) in which explants are grown in vitro
- Understand how micropropagation can be used to produce commercial quantities of genetically identical plants with desirable characteristics
- Describe the stages in the production of cloned mammals involving the introduction of a diploid nucleus from a mature cell into an enucleated egg cell, illustrated by Dolly the sheep
- Understand how cloned transgenic animals can be used to produce human proteins
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Lesson Evaluation
Congratulations on completing the lesson on Cloning. Now that youve explored the key concepts and ideas, its time to put your knowledge to the test. This section offers a variety of practice questions designed to reinforce your understanding and help you gauge your grasp of the material.
You will encounter a mix of question types, including multiple-choice questions, short answer questions, and essay questions. Each question is thoughtfully crafted to assess different aspects of your knowledge and critical thinking skills.
Use this evaluation section as an opportunity to reinforce your understanding of the topic and to identify any areas where you may need additional study. Don't be discouraged by any challenges you encounter; instead, view them as opportunities for growth and improvement.
- What is an explant in micropropagation? A) A mature plant grown from seed B) A small piece of plant tissue taken from the parent C) A genetically modified seed D) A root cutting from an adult plant Answer: B
- In the cloning of Dolly the sheep, where was the diploid nucleus taken from? A) An egg cell B) A sperm cell C) A body cell of an adult sheep D) An embryonic cell Answer: C
- What triggers the enucleated egg cell to start dividing in adult cell cloning? A) Fertilisation by a sperm B) An electric shock C) Addition of hormones D) Exposure to UV light Answer: B
- Which of the following is a disadvantage of cloning plants? A) The plants grow too quickly B) All plants are genetically identical so equally vulnerable to disease C) The plants cannot photosynthesise D) Cloned plants cannot reproduce Answer: B
- What is pharming? A) Growing crops on fish farms B) Using cloned transgenic animals to produce human proteins in their milk C) Selective breeding of dairy cattle D) Fermenting milk to make yoghurt Answer: B
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