CloningIn biotechnology, cloning refers to the

different processes used for

duplicating biological material

(ex. DNA fragments, cells or organisms)

.

The 3 Types of Cloning Technologies:

1. Recombinant DNA Technology/DNA CloningTransfer DNA fragment from one organism to a bacterial plasmid (self-regulating)

Isolate DNA fragment with gene of interest from chromosomal DNA

Join the DNA fragment with a plasmid to create recombinant DNA

Introduce recombinant DNA into suitable host cell for reproduction with host cell DNA

The 3 Types of Cloning Technologies:

2. Reproductive Cloning (“Dolly”)Generate an animal with the same nuclear DNA as another currently or previously existing animal (Somatic Cell Nuclear Transfer)

Transfer genetic material from nucleus of donor adult cell to an enucleated egg (egg without a nucleus and no genetic material)

Reconstructed egg with DNA from donor cell is stimulated to allow for cell division (chemicals/electric current)

Cloned embryo reaches a suitable stage and is transferred to uterus of a female host (for development birth)

**Not truly an identical clone!

Animals that have been cloned:

Tadpole (1950)Sheep

(Dolly – 1996-2003, 1 success out of 276 tries)

GoatsCowsMicePigsCats

RabbitsGaur

The 3 Types of Cloning Technologies:

3. Therapeutic Cloning“Embryo cloning”: production of human embryos for use

in researchHarvest stem cells for use in studying human development and to treat disease

Cells can be used to generate almost any type of specialized cell in human bodyCells extracted from egg after division for 5 days (blastocyst stage)Extraction process destroys embryo (*Ethical concerns**)Perhaps stem cells can one day be used to replace cells to treat heart disease, Alzheimer's, cancer, and other diseases

Cloned Organs for use in Transplants

Scientists hope that one day therapeutic cloning can be used to generate tissues and organs for transplants

TO DO THIS…Extract DNA from person in need of a transplant and insert into an

enucleated egg

Egg with patient's DNA starts to divide

Embryonic stem cells are harvested

Stem cells would be used to generate an organ or tissue that is a genetic match to the recipient

The cloned organ could then be transplanted into the patient without the risk of tissue rejection

**If organs could be generated from cloned human embryos, the need for organ donation could be significantly reduced.

Challenges and RisksMore effective technologies are needed

Expensive

Low success rates-more than 90% of cloning attempts fail to

produce viable offspring-more than 100 nuclear transfer procedures could

be required to produce one viable clone

Cloned animals may have compromised immune function, higher rates of infection, tumor growth and other disorders

Early/mysterious death, abnormally large, do not live long enough to generate good data about how clones age, gene expression abnormalities

Should Humans Be Cloned?

Due to inefficiency (only 2% success rate) and lack of understanding about reproductive cloning, many scientists and physicians strongly believe that it would be unethical

Most attempts to clone mammals fail ~ 30% of clones born alive are affected with "large-

offspring syndrome" and other debilitating conditions Several cloned animals have died prematurely from

infections and other complications.

Should Humans Be Cloned?

The same problems would be expected in human cloning

Scientists also don’t know how cloning could impact mental development.

While factors such as intellect and mood may not be as important for a cow or a mouse, they are crucial for the development of healthy humans

With so many unknowns, the attempt to clone humans at this time is considered potentially dangerous and ethically irresponsible.

What do YOU think?