Chapter 3

Cloning

Background | Classroom Applications | Internet Resources | Appendices

Appendices


Appendix A: Glossary (Printer-Friendly Format)

Breed: To produce (offspring); give birth or hatch.

Clone: A population of identical molecules, cells, or organisms derived from a common source. Because no genetic material is combined (as in sexual reproduction), a clone is genetically identical to the parent.

Consent: To indicate or express a willingness.

Culture: Microorganisms, tissue cells, or other living matter grown in a specially prepared nutrient medium.

Crop: Cultivated plants or agricultural produce, such as grains, vegetables, or fruit.

Cystic fibrosis: (Abbreviation CF) A hereditary disease that usually develops during early childhood and mainly affects the pancreas, respiratory system, and sweat glands. It usually results in chronic respiratory infections and impaired pancreatic function.

Dinosaur: Any of various extinct, often gigantic reptiles.

Donor: One from whom blood, tissue, or an organ is taken for use in a transfusion or transplant. (Note: can also be used as an adjective, as in “embryonic donor cells.”

Embryonic: 1. Of or relating to an embryo; 2. Of an organism prior to birth or hatching; as in “in the embryonic stage.”

Emphysema: An abnormal condition of the lungs characterized by decreased respiratory function; associated with smoking, chronic bronchitis, or old age.

Endangered: Faced with the danger of extinction: an endangered species.

Fertilize: Make fertile or productive 2. Introduce semen into (a female).

Fetal: Of, relating to, characteristic of, or being a fetus: a fertilized egg.

Fission: An asexual (non-sexual) reproductive process in which a one-cell organism divides into two or more independently maturing cells.

Fossil: A remnant or trace of an organism of a past geologic age, such as a skeleton or leaf imprint, embedded and preserved in rock.

Gaur: A large East Indian species of wild cattle. For more information: http://www.nature.ca/notebooks/english/gaur.htm

Gregor Mendel: Founder of the science of genetics (1822–1884). An Austrian monk and botanist.

Hemophilia: A genetic blood disorder in which the blood fails to clot normally. This disorder is hereditary and is due to a deficiency in or an abnormality of one of the clotting factors. Hemophilia is manifested almost exclusively in males.

Hormone: A naturally occurring substance secreted by specialized cells that affects the behavior of other cells.

Husbandry: 1. The act or practice of cultivating crops and breeding and raising livestock; agriculture. 2. The application of scientific principles to agriculture, especially to animal breeding.

Implant: 1. To put an object or a device in a person or animal via surgery.

Manipulate: To handle and move in an examination or for therapeutic purposes: manipulate a joint; manipulate the position of a fetus during delivery.

Mitosis: The entire process of cell division including division of the nucleus and the cytoplasm.

Nucleus: A large circular structure within a living cell that contains the cell's hereditary material and controls its metabolism, growth, and reproduction.

Offspring: A child; a daughter or son.

Organism: An individual life form, such as a plant or an animal; a body made up of organs or other parts that work together to carry out the various processes of life.

Protein: The principal constituent of all cells, essentially consisting of combinations of amino acids and peptide linkages.

Reject: To resist the introduction of (a transplanted organ or tissue); fail to accept as part of one's own body.

Replicate: To make an exact copy or copies of (genetic material, a cell, or an organism).

Reproduce: To generate offspring by sexual or asexual (non-sexual) means.

Roots: The usually underground portion of a plant that serves as support, draws minerals and water from the surrounding soil, and sometimes stores food.

Surrogate: One that takes the place of another; a substitute: a surrogate mother.

Trait: A genetically determined characteristic or condition: a recessive trait.

Transplant: To transfer (tissue or an organ) from one body or body part to another.

Uterus: A hollow muscular organ located in the pelvic cavity of female mammals in which the fertilized egg implants and develops. Also called a womb.

Via: 1. By way of. 2. By means of.

Vital: Necessary to the continuation of life; life-sustaining: a vital organ, vital nutrients.

Woolly mammoth: Hairy extinct mammoth common in colder portions of the northern hemisphere. For more information: http://dsc.discovery.com/convergence/landofmammoth/dispatches/dispatch.html

Womb: A hollow muscular organ located in the pelvic cavity of female mammals in which the fertilized egg implants and develops. Also called a uterus.

 

Appendix B (Printer-Friendly Format)

Sample Student Handout 1 for Word Family Exercise

Directions: Complete the chart with the missing parts of speech for each vocabulary item.  Circle each word that is new for you, and ask your classmates or teacher for its definition.

Verb

Noun

Adjective

to clone

a clone

cloning/ cloned

to replicate

    

to manipulate

    

to test

    
 

an implant

  
 

a reproduction

  
 

a rejection

  
 

a preservation

  

 

Appendix C (Printer-Friendly Format)

Story for Warm Up Activity
Very soon after the beginning of the world, God decided he was not too pleased with his creation. He decided to destroy the earth by making it rain and flooding everything. However, to preserve those things that pleased him, he asked one of his faithful people, Noah, to help him. He came to Noah and told him that the world would be destroyed by flood. He gave Noah exact directions for building an ark, a boat that would be large enough to hold his entire family and two of every animal in creation. Noah set about building the ark as God had directed. Just as he completed it, a heavy rain began to fall. Noah loaded all the animal pairs, one male and one female of each species, onto the ark. It rained forty days and forty nights, and the rain destroyed everything on earth. God had instructed Noah not to leave the ark until it was safe. To see if it was safe, Noah sent a dove out from the ark to find dry land. When the dove returned with an olive branch, Noah knew it was safe to leave the ark. When all the animals and members of Noah’s family had returned to dry land, a rainbow appeared in the sky. This was a sign that God would never again destroy the earth by water.

 

Appendix D (Printer-Friendly Format)

Handout 2 for Students in Group A

What is cloning?
Unlike sexual reproduction, which combines the genetic material of two individuals, cloning involves creating a new organism or individual by copying the genetic material of only one original organism. Cloning can be done in two ways: (1) fission, a cell dividing into two cells or (2) mitosis, the nucleus of a cell dividing with each chromosome splitting into two.

How does cloning work?
In its most basic form, cloning involves three steps. In the first step, scientists take cells from an individual whose characteristics they want to copy. They place these cells, which are called donor cells, into a liquid culture. This culture contains nutrients and stops the cells from dividing. In the second step, an unfertilized egg is taken from a female. Its nucleus is removed, leaving an empty egg cell. The donor cell is then placed into the empty egg. This process creates an embryo that is an exact copy of the donor and not the mother. In the final step, the embryo is put into the uterus of a female of the species and arrives into the world via the natural birth process.

What is the most famous case of cloning?
Dolly the sheep. In 1997, scientists successfully cloned an adult mammal, the Finn Dorset sheep Dolly. Overnight, she became the most famous animal in the world. Although the technology used to clone Dolly was experimental at the time, it has proven useful in the years since she first appeared. Now, scientists are cloning cows, chickens, and pigs. They are also able to produce clones from animal fetal cells quite easily.

 

Handout 2 for Students in Group B

Which organisms are the most frequently cloned today? Plants. For centuries, people have taken roots or stems of plants in order to make genetically identical copies. Usually this is done by choosing the best plant (for example, the most decorative or unusual), cutting a root or branch from it, and placing that cutting in water or soil. The cells will then divide and double in size every six weeks until the cutting develops roots. At this point, it is ready to be planted. It will then grow into an exact copy of the parent plant.

 

Is cloning unnatural?
No, cloning already occurs in nature. In fact, the only way that many organisms (for example, bacteria, yeast, snails, and shrimp) can reproduce is through cloning. Mammals reproduce naturally only through sexual reproduction. Thus, only scientists working in a laboratory can clone a mammal. The problem with cloning, however, is that it does not improve the genetic makeup of a species.

What is the difference between cloning and breeding?
For years, specialists in animal husbandry have been able to breed characteristics in and out of animals, thereby creating improved animal breeds. For example, dog breeders have been able to control the genetic makeup of species to obtain certain physical characteristics such as eye or fur color, size, or special abilities such as speed or herding. Breeding, however, is different from cloning in two ways. First, it can only be done with embryonic cells (cells that result in the production of offspring). Second, breeding does not produce an exact replica. Breeders can calculate the probability of obtaining a certain trait, but to actually obtain this trait they may have to try several times. With cloning, scientists can choose any healthy individual whose characteristics they wish to clone and create an exact copy by using cells from that animal.

 

Handout 2 for Students in Group C

What is the difference between an identical twin and a clone?
Both identical twins and clones consist of the exact same genetic material. But a clone cannot be considered an identical twin of the donor because it does not share the same time in the womb. Twins experience the same environmental factors before birth (such as nutrition and exposure to stress, hormones, alcohol, and drugs), which play an enormous role in their physical and mental development. The clone, on the other hand, only shares genetic material with its donor and lacks the prenatal environmental exposure of an identical twin.

Could cloning be used to produce vital organs for transplant?
Hypothetically yes. The only way to do this, however, would be to reproduce the entire individual, including its organs. This practice would raise ethical questions. Time is also a problem. It would take a long time for a donor’s organs to be mature enough to be removed from the donor and used for transplant. In addition, scientists are unsure whether transplanted organs from cloning would be accepted or rejected by the recipient individual.

 

Handout 2 for Students in Group D

Could endangered species be saved through cloning?
Possibly. At the present time, the success of this is unlikely. It took 276 tries to clone Dolly the sheep. But if the success rate of cloning increases, it could be a way to increase the population of endangered species or animals that are difficult to breed.

Could extinct species be revived using cloning?
This would be more difficult. Cloning extinct animals poses two problems. First, donor cells must be taken from living organisms. Unless an extinct animal is found completely frozen (such as the wooly mammoth recently discovered in the Arctic), it would be impossible to find living cells. For example, because the fossil bones of dinosaurs contain no living cells, a dinosaur cannot be cloned. Second, current cloning technology requires a surrogate mother and an egg cell from a living female of the same species. Females normally cannot give birth to an animal from a different species. It is unlikely, for instance, that a female elephant could donate an egg cell and give birth to a wooly mammoth.

 

Handout 2 for Students in Group E

What are the benefits of cloning?
We are more certain of obtaining desired traits through cloning than through conventional breeding. For example, cloning could benefit crop engineering by creating foods that are more nutritious, disease free, and plentiful. Cloning could also help in the prevention and cure of diseases. For instance, the same laboratory that created Dolly the sheep is now working to create eggs that contain anticancer proteins to prevent various forms of cancer (such as fast growing forms of skin cancer). Dolly herself was cloned to produce a sheep whose milk had more proteins that are believed to help treat diseases such as emphysema, hemophilia, and cystic fibrosis.

 

Handout 2 for Students in Group F

What are the disadvantages of cloning?
One potential disadvantage of cloning is that “breeding” humans would become easier. While we have done this for centuries with other large animals such as race horses, cloning humans raises moral and ethical concerns. There is great potential for abuse if humans are able to design their offspring. The ability to breed in or out certain traits would raise questions of how tall or how intelligent we would want our children to be, or what color skin and eyes we would want them to have. These are questions that make us uncomfortable. In addition, it would be problematic to invest so much in changing or improving human genetic makeup because we might ignore the impact that the environment has on an individual’s development. A further problem is that clones could be misused, for example, as spare part tissues and organs or as slave labor.

 

Appendix E (Printer-Friendly Format)

Handout 3 for Activity 1

  1. What was the first adult mammal to be cloned?

  2. What steps do scientists follow to clone a large animal (such as a pig or a cow)?

  3. Is cloning something that only scientists can do?

  4. What makes an identical twin different from a clone?

  5. What is the controversy surrounding the cloning of organisms to produce vital organs?

  6. Why can cloning be used on endangered species but not on extinct species?

  7. Name two benefits and two drawbacks of cloning.

Answer Key for Activity 1

  1. Dolly the sheep

  2. First, they extract a cell from a donor animal whose traits they want to replicate. Second, they place the donor cells in a liquid that stops cell division. Third, they take an unfertilized egg from a female of the same species and remove its nucleus. Fourth, they implant the donor cell into the egg cell. Finally, they implant the newly created embryo into the uterus of a female of the species.

  3. No. Anyone can clone a plant by taking a cutting and placing it in a medium that allows it to grow, such as water or soil. In addition, many species such as bacteria reproduce themselves via cloning.

  4. Identical twins share the exact same pre-natal environmental conditions, but clones do not share an environment with the donor cell.

  5. First, it is currently impossible to produce just an organ. The production of a vital organ requires reproducing an entire individual. This takes time and raises the ethical question of consent of the cloned individual to have its organs used in this way.

  6. Because cloning requires a live cell. Fossil bones usually contain no living cells unless they are preserved in ice. However, endangered species are still alive and living cells can be taken from them.

  7. The benefits are: (1) it allows for exact replication of the donor’s traits or characteristics and (2) it can help in preventing and curing diseases through the reproduction of individuals that are free of certain diseases or that possess certain disease-fighting or disease-resistant proteins. The drawbacks are: (1) it opens the way for humans to “play God” by breeding human beings as if they were animals and (2) it may lead us to overestimate the impact that genes have on our behavior and identity.

 

Appendix F (Printer-Friendly Format)

Handout 4 for Activity 2

Uses of Cloning

  1. Scientists have successfully cloned five female pigs: Millie, Christa, Alexis, Carrel, and Dotcom. These pigs were the first ever to be cloned, thus contributing to basic scientific knowledge about cloning. Pigs are now being cloned as organ donors. This idea may sound strange and impossible, but pig organs (such as the heart and liver) are similar in form and function to those of other mammals.

  2. Recently, the last of an endangered species of goat, the bucardo, died in a winter storm. The carcass of the animal was frozen and preserved. Scientists are preparing to recreate the species by cloning one of her cells and implanting it in the uterus of a female from another goat species.

  3. Teruhiko Wakayama, a 31-year-old postdoctoral student at the University of Hawaii, decided to see if he could use the technology developed to produce Dolly the sheep to clone mice. Not only did he succeed but he perfected the technique so that 3 percent of his clones survived. The cloned mice were normal and their DNA was so robust that they themselves could be cloned and their clones could be cloned. They produced three generations of identical mice for a total of 50 mice.

  4. Scientists are working on cloning hens that lay eggs that contain antibodies against cancer. These eggs could be a natural anticancer drug for those human beings who ate them.

  5. Scientists discovered an intact woolly mammoth preserved in ice. Their excavation techniques allowed them to preserve the mammoth's soft tissue. Several labs around the world have proposed extracting DNA from this soft tissue to see of they can use it to clone the mammoth.

  6. Scientists may be able to control aging through cloning. In the case of Dolly the sheep, her cells appeared to be the same age as the adult female donor from which she was cloned. In other words, she is older than her chronological age. However, in the case of six cloned cows created through a different cloning technique, their cells appear to be younger than the cow's actual chronological age.

Appendix G (Printer-Friendly Format)

Handout 5 for Activity 3: The Cloning Forum

Person’s name: Ken

E-mail: tokyoken@mail.com

From: Tokyo, Japan

Opinion: I think that the cloning of Dolly is the most important scientific breakthrough ever. Its medical benefits alone justify spending money on the project. While there are obvious concerns about abusing the technology of cloning, history shows that we cannot turn back. What we need is government action to outline ethical codes for the use of cloning.

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Person’s name: Richard

E-mail: iowacityrich@stream.net

From: Iowa City, Iowa

Opinion: It is morally wrong under any circumstances to clone a human being and we should not even consider it. What is the use of cloning a human being? We already have a population problem in many countries. Where would we put any more people? I’m also afraid that we aren’t wise enough to control this technology, which allows us to play God.

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Person’s name: Wendy

E-mail: funkychick@link.net

From: San Bernardino, California

Opinion: As an academic who is deeply interested in biological matters, I want to express my opinion about the cloning of Dolly. This opens up important opportunities in health and the environment. Wouldn’t it be great if we could preserve all the endangered species of the world and bring the world’s ecosystem back into balance? Isn’t this a better use of our resources than waging wars and developing new technologies that further pollute our environment? It’s true, however, that we could easily misuse the power that cloning provides us. Despite the fears that cloning could easily be abused, I believe that human beings can and have learned from their past mistakes and that we can make intelligent use of this new and exciting technology.

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Person’s name: Kamil

E-mail: linguist@nairobiu.com

From: Nairobi, Kenya

Opinion: There has been much discussion about the fact that a clone will provide a perfect source for donor organs. If we consider the clone as a life like any other, however, this raises the very serious ethical and moral dilemma of sacrificing one life to save another. I personally believe that this is unethical from any perspective. What it ultimately comes down to is choosing the value of the original over the value of the copy. While this may be true for works of art, it doesn’t apply to sentient beings.

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Person’s name: Christos

E-mail: christos@athens.net

From: Athens, Greece

Opinion: Cloning of humans would create a very confusing society with doubles and triples of everyone walking around. How would we distinguish identity? Would clones be issued the same passports, driver’s licenses, and identity cards? What about credit checks? How would the original individual prove that s/he was the original and not a copy? How would this change our understanding of individuality and self identity?

 

Appendix H (Printer-Friendly Format)

Sample Blackboard Layout of Word Wheel for Cool Down Activity

 

 

 

 

 

 

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