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Lecture 34. the human genome project and human cloning

The human genome project

Begun formally in 1990, the U.S. Human Genome Project was a 13-year effort coordinated by the U.S. Department of Energy and the National Institutes of Health. The project originally was planned to last 15 years, but rapid technological advances accelerated the completion date to 2003. Project goals were to

  • identify all the approximately 20,000-25,000 genes in human DNA;
  • determine the sequences of the 3 billion chemical base pairs that make up human DNA;
  • store this information in databases;
  • improve tools for data analysis;
  • transfer related technologies to the private sector; and
  • address the ethical, legal, and social issues (ELSI) that may arise from the project.

To help achieve these goals, researchers also studied the genetic makeup of several nonhuman organisms. These include the common human gut bacterium Escherichia coli, the fruit fly, and the laboratory mouse.

A unique aspect of the U.S. Human Genome Project is that it was the first large scientific undertaking to address potential ELSI implications arising from project data.

Another important feature of the project was the federal government's long-standing dedication to the transfer of technology to the private sector. By licensing technologies to private companies and awarding grants for innovative research, the project catalyzed the multibillion-dollar U.S. biotechnology industry and fostered the development of new medical applications .

Sequence and analysis of the human genome working draft was published in February 2001 and April 2003 issues of Nature and Science. See an index of these papers and learn more about the insights gained from them .

Human cloning: reproductive and therapeutic cloning

Cloning is the process of asexually producing a group of cells (clones), all genetically identical to the original ancestor. The word is also used in recombinant DNA manipulation procedures to produce multiple copies of a single gene or segment of DNA. It is more commonly known as the production of a cell or an organism from a somatic cell of an organism with the same nuclear genomic (genetic) characters - without fertilization. A clone is a collection of cells or organisms that are genetically identical. Some vegetables are made this way, like asparagus, or flowers like orchids.

Human reproductive cloning is the production of a human fetus from a single cell by asexual reproduction. In 2001 a cloned embryo was reported made by nuclear transfer, though in 1993 cloned embryos were made by splitting human embryos. In the late 1990s reproductive cloning was used to produce clones of the adults of a number of mammalian species, including sheep, mice and pigs. The most famous of these was Dolly, the sheep. Many countries rushed to outlaw the possibility of reproductive cloning in humans. Most mammalian embryos can only be split into 2-4 clones; after that the cells lack the ability to start development into a human being.

Therapeutic cloning is the cloning of embryos containing DNA from an individual's own cell to generate a source of embryonic stem (ES) cell-progenitor cells that can differentiate into the different cell types of the body. ES cells are capable of generating all cell types, unlike multipotent adult-derived stem cells which generate many but not all cell types. The aim is to produce healthy replacement tissue that would be readily available. Since it is from the same body it is immunocompatible so that the recipients would not have to take immunosuppressant drugs for the rest of their lives, as they do if they receive an organ from another person.

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Source:  OpenStax, Genetics. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10782/1.1
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