Human CloningHuman Cloning

IntroductionIntroduction

Cloning- the process of making an identical Cloning- the process of making an identical organism through nonsexual meansorganism through nonsexual means

In 1997 Ian Wilmut at the Roslin Institute In 1997 Ian Wilmut at the Roslin Institute in Edinburgh, Scotland successfully clone in Edinburgh, Scotland successfully clone the first mammal, a sheep name Dolly the first mammal, a sheep name Dolly

In January 2001 scientist Panayiotis Zavos In January 2001 scientist Panayiotis Zavos and researcher Severino Antinori said that and researcher Severino Antinori said that they are planned to clone a human in the they are planned to clone a human in the next two years.next two years.

Are there different types of Are there different types of cloning?cloning?

The following three types of cloning The following three types of cloning technologies will be discussed: technologies will be discussed:

(1) recombinant DNA technology or (1) recombinant DNA technology or DNA cloningDNA cloning

(2) reproductive cloning(2) reproductive cloning (3) therapeutic cloning. (3) therapeutic cloning.

Recombinant DNA Technology Recombinant DNA Technology or DNA Cloningor DNA Cloning

The terms "recombinant DNA technology," The terms "recombinant DNA technology," "DNA cloning," "molecular cloning,"or "gene "DNA cloning," "molecular cloning,"or "gene cloning" all refer to the same process:cloning" all refer to the same process: the transfer of a DNA fragment of interest from the transfer of a DNA fragment of interest from

one organism to a self-replicating genetic one organism to a self-replicating genetic element such as a bacterial plasmid. element such as a bacterial plasmid.

The DNA of interest can then be propagated in a The DNA of interest can then be propagated in a foreign host cell. This technology has been foreign host cell. This technology has been around since the 1970s, and it has become a around since the 1970s, and it has become a common practice in molecular biology labs common practice in molecular biology labs today. today.

PlasmidsPlasmids

Scientists studying a particular gene Scientists studying a particular gene often use bacterial plasmids to often use bacterial plasmids to generate multiple copies of the same generate multiple copies of the same gene. Plasmids are self-replicating gene. Plasmids are self-replicating extra-chromosomal circular DNA extra-chromosomal circular DNA molecules molecules

Clone a geneClone a gene To "clone a gene," a DNA fragment To "clone a gene," a DNA fragment

containing the gene of interest is isolated containing the gene of interest is isolated from chromosomal DNA using restriction from chromosomal DNA using restriction enzymes and then united with a plasmid that enzymes and then united with a plasmid that has been cut with the same restriction has been cut with the same restriction enzymes. enzymes.

When the fragment of chromosomal DNA is When the fragment of chromosomal DNA is joined with its cloning vector in the lab, it is joined with its cloning vector in the lab, it is called a "recombinant DNA molecule." called a "recombinant DNA molecule."

Following introduction into suitable host Following introduction into suitable host cells, the recombinant DNA can then be cells, the recombinant DNA can then be reproduced along with the host cell DNA reproduced along with the host cell DNA

Reproductive Cloning Reproductive Cloning Reproductive cloning is a technology used to Reproductive cloning is a technology used to

generate an animal that has the same nuclear generate an animal that has the same nuclear DNA as another currently or previously DNA as another currently or previously existing animal existing animal

In a process called "somatic cell nuclear In a process called "somatic cell nuclear transfer" (SCNT), scientists transfer genetic transfer" (SCNT), scientists transfer genetic material from the nucleus of a donor adult cell material from the nucleus of a donor adult cell to an egg whose nucleus, and thus its genetic to an egg whose nucleus, and thus its genetic material, has been removed. material, has been removed.

The reconstructed egg containing the DNA The reconstructed egg containing the DNA from a donor cell must be treated with from a donor cell must be treated with chemicals or electric current in order to chemicals or electric current in order to stimulate cell division. Once the cloned stimulate cell division. Once the cloned embryo reaches a suitable stage, it is embryo reaches a suitable stage, it is transferred to the uterus of a female host transferred to the uterus of a female host where it continues to develop until birth. where it continues to develop until birth.

Human Cloning Human Cloning

Somatic cell nuclearSomatic cell nuclear

transfertransfer Human repair kit, Human repair kit,

they can grow organs they can grow organs such as hearts, livers, such as hearts, livers, and skins.and skins.

They can also be used They can also be used to grow neurons to to grow neurons to cure those who suffer cure those who suffer from Alzheimer's, from Alzheimer's, Parkinson's.Parkinson's.

Therapeutic Cloning Therapeutic Cloning Therapeutic cloning, also called "embryo Therapeutic cloning, also called "embryo

cloning," is the production of human embryos cloning," is the production of human embryos for use in research. The goal of this process is for use in research. The goal of this process is not to create cloned human beings, but rather not to create cloned human beings, but rather to harvest stem cells that can be used to study to harvest stem cells that can be used to study human development and to treat disease. human development and to treat disease.

Stem cells are important to biomedical Stem cells are important to biomedical researchers because they can be used to researchers because they can be used to generate virtually any type of specialized cell in generate virtually any type of specialized cell in the human body the human body

Many researchers hope that one day stem cells Many researchers hope that one day stem cells can be used to serve as replacement cells to can be used to serve as replacement cells to treat disease treat disease

How can cloning technologies How can cloning technologies be used?be used?

Recombinant DNA technology is important Recombinant DNA technology is important for learning about other related technologies, for learning about other related technologies, such as gene therapy, genetic engineering of such as gene therapy, genetic engineering of organisms, and sequencing genomes. organisms, and sequencing genomes.

Gene therapy can be used to treat certain Gene therapy can be used to treat certain genetic conditions by introducing virus genetic conditions by introducing virus vectors that carry corrected copies of faulty vectors that carry corrected copies of faulty genes into the cells of a host organism.genes into the cells of a host organism.

reproductive cloning can be used to develop reproductive cloning can be used to develop efficient ways to reliably reproduce animals efficient ways to reliably reproduce animals with special qualities. For example, drug-with special qualities. For example, drug-producing animals or animals that have been producing animals or animals that have been genetically altered to serve as models for genetically altered to serve as models for studying human disease could be mass-studying human disease could be mass-produced. produced.

More Cloning More Cloning technologiestechnologies

Genes from different organisms that Genes from different organisms that improve taste and nutritional value or improve taste and nutritional value or provide resistance to particular types of provide resistance to particular types of disease can be used to genetically disease can be used to genetically engineer food crops.engineer food crops.

Therapeutic cloning technology may some Therapeutic cloning technology may some day be used in humans to produce whole day be used in humans to produce whole organs from single cells or to produce organs from single cells or to produce healthy cells that can replace damaged healthy cells that can replace damaged cells in degenerative diseases such as cells in degenerative diseases such as Alzheimer's or Parkinson's Alzheimer's or Parkinson's

What animals have been What animals have been cloned? cloned?

Hundreds of cloned animals exist today, but Hundreds of cloned animals exist today, but the number of different species is limited. the number of different species is limited. Attempts at cloning certain species such as Attempts at cloning certain species such as monkeys, chickens, horses, and dogs, have monkeys, chickens, horses, and dogs, have been unsuccessful. Some species may be more been unsuccessful. Some species may be more resistant to somatic cell nuclear transfer than resistant to somatic cell nuclear transfer than others. others.

The process of stripping the nucleus from an The process of stripping the nucleus from an egg cell and replacing it with the nucleus of a egg cell and replacing it with the nucleus of a donor cell is a traumatic one, and donor cell is a traumatic one, and improvements in cloning technologies may be improvements in cloning technologies may be needed before many species can be cloned needed before many species can be cloned successfully. successfully.

OrganOrgan

TransplantationTransplantation Thousands of people Thousands of people

die every year waiting die every year waiting for a transplantfor a transplant

Cloning technology Cloning technology could someday be used could someday be used to produce whole to produce whole organs.organs.

Embryonic stem cells Embryonic stem cells also have the potential also have the potential for use in the for use in the production of tissues.production of tissues.

www.tufts-nemc.org

www.c-science.com

What are the risks of What are the risks of cloning? cloning?

Reproductive cloning is expensive and highly Reproductive cloning is expensive and highly inefficient. More than 90% of cloning attempts inefficient. More than 90% of cloning attempts fail to produce viable offspring. More than 100 fail to produce viable offspring. More than 100 nuclear transfer procedures could be required nuclear transfer procedures could be required to produce one viable clone. to produce one viable clone.

In addition to low success rates, cloned animals In addition to low success rates, cloned animals tend to have more compromised immune tend to have more compromised immune function and higher rates of infection, tumor function and higher rates of infection, tumor growth, and other disorders. growth, and other disorders.

Many cloned animals have not lived long Many cloned animals have not lived long enough to generate good data about how clones enough to generate good data about how clones age. age.

Clones have been known to die mysteriously. Clones have been known to die mysteriously. For example, Australia's first cloned sheep For example, Australia's first cloned sheep appeared healthy and energetic on the day she appeared healthy and energetic on the day she died, and the results from her autopsy failed to died, and the results from her autopsy failed to determine a cause of death. determine a cause of death.

Bottom Line Bottom Line We still have A LOT to learn about DNA and We still have A LOT to learn about DNA and

the genetic codethe genetic code As genetic engineers we have much to As genetic engineers we have much to

understand and we are still in the infancy of understand and we are still in the infancy of our understanding of our own genetic code. our understanding of our own genetic code.

As we learn and understand more genetic As we learn and understand more genetic engineering will be a part of every day life. engineering will be a part of every day life.

WeWe’’ve made great leaps in a very short time ve made great leaps in a very short time since the discovery of DNA but we still have since the discovery of DNA but we still have a long way to go. . . . . a long way to go. . . . .