Topic: Mammalian cloning

Target group

High school / technical school student

Core curriculum

General requirements

V. Reasoning and applying the acquired knowledge to solving biological problems. Student:

1. interprets information and explains causal relationships between processes and phenomena, formulates conclusions.

Specific requirements

VIII. Biotechnology. Basics of genetic engineering. Student:

7. describes the cloning of organisms and presents the importance of this process.

General aim of education

The students explain the possibilities of today's science for cloning organisms.

Key competences

• communication in foreign languages;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• present the history of cloning;

• explain cloning techniques;

• assess the usefulness of human cell cloning;

• exchange the advantages and disadvantages as well as hopes and fears related to mammal cloning.

Methods/techniques

• expository

  • talk.

• activating

  • discussion.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• notebook and crayons/felt‑tip pens;

• interactive whiteboard, tablets/computers;

• interview with Olga Woźniak with prof. Keith Campbell (Olga Woźniak, Dolly and her sisters (interview with Professor Keith Campbell), [in:] „Gazeta Wyborcza”, February 18‑19, 2012, pp. 30‑31).

Lesson plan overview

Before classes

• Students get acquainted with the content of the abstract. They prepare to work on the lesson in such a way to be able to summarize the material read in their own words and solve the tasks themselves.

Introduction

• The teacher gives the topic, the goals of the lesson in a language understandable for the student, and the criteria of success.

Realization

• The teacher explains what clones are and based on the interactive illustration „How do clones of organisms arise?” Discusses aspects related to the prevalence of clones and clones of some animals, and sporadic occurrence among mammals. The teacher also discusses the most important methods by which scientists have made successful attempts to clone animals.

• The students, working in groups, read an interview with prof. Keith Campbell and on the basis of the information contained in it, try to determine why, despite numerous attempts, cloning is not always successful. Then all teams share their conclusions.

• The teacher initiates a discussion about the goals of cloning livestock and the prospects of creating clones of animals classified as extinct and extinct species.

• Students perform exercises and commands. The teacher checks and supplements the answers, providing students with the necessary information. Provides feedback..

Summary

• The teacher briefly presents the most important issues discussed in class. He answers the additional questions of the proteges and explains all their doubts. Students complete notes.

Homework

• Listen to the abstract recording at home. Pay attention to pronunciation, accent and intonation. Learn to pronounce the words learned during the lesson.

• What difficulties do you need to overcome in order to make cloning livestock a common practice?.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Mammalian cloning

Cloning of organisms consist in creating their genetically identical copies. This process sometimes occurs in nature, for example, during the development of a human embryo. Then, during the first two weeks of zygote development, the embryo divides and each of its parts independently develops into a separate organism. Children born this way come from one pair of gametes and therefore have the same genotype which makes their physicality and mentality very similar. Identical (monozygotic) twins are thus their own copies – clones. However, the birth of such twins in humans is quite rare and affects about 0.35% of all pregnancies.

The first attempts at cloning animals were made at the turn of the 19th century. They consisted in dividing an embryo consisting of 2‑8 cells. Unfortunately, the resulting twin nuclei showed high mortality. In 1901, Hans Spemann succeeded in his attempts and divided a salamander embryo into two parts. A fully functional individual developed from each of them. This experience shows that embryo cells at early stages of division retain genetic information necessary for a complete organism to be born. Later on, numerous attempts at cloning mouse and frog embryos were made, but they failed.

As late as 1996, i.e. after changing the technique of creating embryos, the first cloned animal – Dolly – was born. A mouse was cloned two years later and a rhesus monkey – later on. At the beginning of the 21st century, as a result of the multiplication of organisms, scientists obtained a pig and 5 identical piglets, a buffalo, a cow, a rabbit and even a cat named CopyCat. A deer, a Snuppy dog and a wolf were successfully cloned later. A camel was cloned from cells isolated from ovaries of a female killed for meat 4 years earlier.

The most commonly used method of cloning animals is the so‑called cellular transplantation method. It consists in replacing an egg cell nucleus of one individual with a somatic cell nucleus of another individual. Cloning takes place at several stages. The nucleus of the recipient's egg cell is removed. A diploid cell is isolated from a selected tissue (e.g. skin) of another organism of the same species (donor), and the nucleus of the cell is removed and transferred to a pre‑prepared egg. It is then subjected to an electric shock which causes it to divide and create a several cell embryo. All these stages take place in vitro, i.e. outside the organism. To allow the embryo to develop further, it must be implanted in the womb of a surrogate mother – a female of the same species as the clone or very closely related to it.

Cloning makes it possible to reproduce extinct species if their genetic material is preserved. One example is a subspecies of a Pyrenean ibex (bucardo) which has been eradicated in recent years. It was possible, as the frozen skin of one individual of the subspecies has been stored since 1999, so scientists had complete genetic material. Egg cells were taken from domestic goats closely related to a bucardo, and surrogate mothers were female crossbreeds of a bucardo and a male goat. Embryos (clones) were implanted into 208 goats, of which 7 got pregnant, but only one female gave birth to a bucardo lamb. Unfortunately, the animal lived for only 7 minutes due to lung malformations. The premature termination of pregnancy in the other goats was due to the fact that the embryonic development environment was not sufficiently similar to that created by females of the proper species. That is why other extinct species, whose DNA we have, cannot be brought back on Earth for now.

At present, cloning makes it possible to preserve particularly rare species threatened with extinction and to increase the number of species whose reproduction is very slow. We face one huge problem when it comes to cloning species threatened with extinction, i.e. obtaining an egg cell. To get a gamete from a female giant panda, you have to put her to sleep which can kill her. A panda surrogate mother can only be a female of other bears. Using mothers of another species to carry pregnancy significantly reduces the chances of success.

A mammoth will not be cloned soon. Complete genetic material has not yet been found in its remains.

• Cloned organisms have identical genetic information.