Natural Sciences – FES 150
Table of Contents
WHAT IS CLONING?3
THE BIRTH OF DOLLY (SHEEP)7
ANNOUNCEMENT TO THE WORLD8
WAS DOLLY ALREADY “OLD” AT BIRTH?9
DOLLY’S FINAL ILLNESS10
WHY WAS DOLLY IMPORTANT?11
WHAT IS THE LONGTERM SIGNIFICANCE OF DOLLY?11
DOLLY’S FACT SHEET12
The possibility of human cloning, raised when Scottish scientists at Roslin Institute created the much-celebrated sheep "Dolly" (Nature 385, 810-13, 1997), aroused worldwide interest and concern because of its scientific implications. A Science magazine also generated uncertainty over the meaning of "cloning" --an umbrella term traditionally used by scientists to describe different processes for duplicating biological material.
WHAT IS CLONING?
Cloning is the production of one or more individual plants or animals (whole or in part) that are genetically identical to an original plant or animal.
There are two commonly discussed types of cloning: therapeutic cloning and reproductive cloning. Therapeutic cloning involves cloning cells from an adult for use in medicine and is an active area of research. Reproductive cloning would involve making cloned humans.
A third type of cloning called replacement/recombinant cloning is a theoretical possibility, and would be a combination of therapeutic and reproductive cloning. Replacement cloning would entail the replacement of an extensively damaged, failed, or failing body through cloning followed by whole or partial brain transplant.
All the information needed to create a new human being is contained in each cell of an existing human being. DNA testing on a human often starts by scraping some cells from the inside of a person's mouth. Living cells can be scraped off of a person's skin. No matter how a cell is obtained, it contains the DNA of the person, and thus contains all of the information required to produce a duplicate or cloned person. Each cell is, in fact, a form of human life for the simple reason that it contains human DNA.
A woman's ovum also contains her DNA. What is involved in somatic cell nuclear transfer is to:
* Take a woman's ovum, and remove its DNA. This converts it to a form of human life into what is basically a factory for creating a pre-embryo. * Remove the DNA from a cell taken from a human, and inserting it into the ovum. * Giving the resulting ovum an electrical shock to start up its embryo making operation. In a small percentage of cases, a pre-embryo will be formed. * The pre-embryo is allowed to develop and produce many stem cells. So far, the procedure is identical to that used in adult DNA cloning. However, the pre-embryo is not implanted in a woman's womb in order to try to produce a pregnancy. * Stem cells are removed from the pre-embryo; this results in its death. * The stem cells would be encouraged to grow into whatever tissue or organ is needed to treat the patient. Stem cells are a unique form of human cell that can theoretically develop into many organs or body parts the body. * The tissue or organ would be transplanted into the patient.
An important factor to remember is that:
| * The original seed cell is a form of human life; it contains human DNA, whether it comes from a skin scraping or is extracted from the inside of a person's mouth.| | * The original ovum is a form of human life; it contains human DNA.| | * The pre-embryo that is produced is a form of human life; it contains human DNA.|
So, there is a continuity of human life from a surplus cell which a human produces by the millions each day, to the pre-embryo.
Theoretically, these stem cells can be used to develop into replacement organs (heart, liver, pancreas, skin, etc) Therapeutic cloning...