|THE LIVING CELL|
A look at the world of the cell
with Boyce Rensberger
May 16, 1997
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in this forum:
Are cancer cells "anarchists" in the body "republic?" Will human organs ever be genetically engineered? What makes humans different from chimpanzees? Will cloning lead to the lose of human individuality? Why hasn't the abortion debate included new information on how human life develops? Where will the most exciting advances in biology come from in the next century?
David Gergen discusses the cellular world with Boyce Rensberger, author of "Life Itself: Exploring The Realm of the Living Cell."
April 24, 1997:
Charlayne Hunter-Gault talks with the doctor who helped a 63-year-old woman become a mother.
March 5, 1997:
The annoucement of Dolly, the cloned sheep, was stunning, but what does cloning mean for society?
February 24, 1997:
Analysis of the revelation that Scottish scientists had cloned a sheep.
January 1, 1997:
Paul Solman reviews the year in genetics.
Browse the NewsHour's index of science coverage.
The Online NewsHour's editors ask:
Humans and chimpanzees share 99+ percent of their DNA. What is it that makes us different from our animal cousins?
Boyce Rensberger responds:
What makes us different is the 1 percent. Actually, I think the usual figure is that we share about 98 percent of our DNA. Basically, we have the same set of genes (essentially 100 percent at this level of comparison) but there are small modifications within the genes. That's where most of the difference comes from.
To change a chimp into a human, you don't need any new kinds of genes, cells or organs. All you need is to change the shapes and sizes of certain tissues a little bit (shorter arms, longer legs--that kind of thing) and to make the brain grow larger and for the brain cells to make more interconnections. There would be a few other changes, but they are similar in nature.
To produce such changes, you need to alter not the gene itself but the regulatory sequences in the adjacent DNA that govern when the gene is activated, how long it keeps cranking out its protein products and when it shuts down.
In sum, we're not all that different. But these comparisons can be misleading. Human genes are something like 40 percent identical to those of yeast.
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