文档介绍：Book 3, Unit 8 CLONING
Tu Yanhua
M0352016
First Stem Cells Extracted from Cloned Human EmbryoPosted: Scientists in South Korea have extracted stem cells from a cloned human embryo - a breakthrough that has potential for treating various diseases but also ignites fears that rogue scientists will use the technology to clone humans.
Part I: Pre-Reading Task
Other scientists have cloned small numbers of human embryos that lived for a short time, but the South Koreans who announced their work last week in the journal Science, apparently eeded on a scale that far outstripped earlier human cloning efforts.
South Korean researchers make medical history
The researchers began with a group of 16 women who were given hormone treatments to produce large numbers of reproductive egg cells. They eventually obtained 242 eggs from the women.
Then the scientists used innovative techniques to strip out the nucleus from each of these egg cells. The nucleus is the portion of the cell containing many of the cell's ic instructions.
The scientists next took body cells from the same women who had donated the egg cells. The body cells have two sets of chromosomes, the full ic blueprint needed to create a human being. The scientists removed these body cells' nuclear material and placed it into the egg cells.
The result was 66 cloned eggs, in effect, human embryos, with the exact ic makeup of the original females. The researchers grew 30 of the embryos for a week to the so-called blastocyst stage, when stem cells could be extracted
Stem cell technology could help cure diseases
Embryonic stem cells are unique because they have the potential to develop into any type of tissue or cell in the body.
The research, called therapeutic cloning, could allow scientists to take a plug of skin or blood sample from a patient and use it to grow tissue, organs or batches of cells. The new cells would have the same ic makeup as the donor and would therefore lower the risk that the injured