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Topic 4: Genetics – 4.4 Genetic engineering and biotechnology

Human Genome Project

The Human Genome Project, completed in April 2003, was an international effort between many independent organizations, which achieved the goal of obtaining a sequence of the human genome – the entire base sequence of the DNA in a human cell.

Only about 25,000 genes (protein-coding sequences) were found(about 100,000 were expected) and a lot of “junk DNA” (DNA not transcribed) was discovered.

Beneficial outcomes of the Human Genome project include:
1. Identification of genes and development of genetic tests for genes that predispose people to genetic disorders.
2. A detailed understanding of the human genome allows the development of therapeutic techniques to combat diseases resultingfrom cellular processes.
3. Comparisons for DNA sequences from different human populations and different species further our understanding of origin of ancestry and evolutionary relationships.

The final benefit has had some controversial consequences, including the discussion of race differences in human genomes.

Read the following article…

What DifferenceMakes a Difference?

In 1851 the Louisiana physician Dr. Samuel Cartwright observed a behavior evident in African African Americans but absent in whites. They tended to run away from slave plantations. He attributed this odd behavior to a disease peculiar to Negroes. He even gave the affliction a name, "drapetomania."
Cartwright's "run-away" disease elicits derisive laughter today. So too do allthe other 19th and early 20th century exertions to distinguish races by facial angle, skull size, cranial index, length of shin bone and blood type. Our growing knowledge of the genome and human evolutionary history help us understand why all such efforts to locate the source of innate racial difference were doomed: it doesn't exist. Most geneticists and anthropologists who study human variationagree that humans just don't come bundled into three or four separate groups according to skin color and other physical traits.
Nonetheless, "discoveries" of racial difference resurface in the press with predictable regularity. Often they spotlight differential rates of diseases, or responses to a drug. Sometimes they zero in on a genetics study.
That was the case recently with a report publishedin Science magazine (Dec. 20, 2002). Noah Rosenberg, Marcus Feldman and others analyzed the variation in 377 different DNA sequences from 1056 individuals from around the world. They found that 95% of the DNA variation they studied is due to differences between individuals within any continent. But they also found they could use the remaining 5% of the variation as genetic "footprints" indicatingthe continent from which an individual's recent ancestors came.
Some were quick to interpret these results as evidence that old-fashioned notions of the "races of man" have been correct all along. But does it? What do these studies actually tell us? And why should our interpretations matter?
Reports about such studies commonly fall prey to three errors: they confuse DNA markers of ancestry withmarkers of race. They mistake the fact that some gene variants are more common in some populations than others as signs of racial "difference" between those populations. And they assume that disparities in group outcomes can be attributed to inborn, or genetic, differences between races.
The idea of biological race assumes traits come packaged together, even color-coded for our convenience, asanthropologist Jonathan Marks jokes. In otherwords, if biological race were real, we'd find that skin color or other "racial" markers would correlate with a suite of other genetic traits. Knowing an individual's "race" should enable us to predict his or her other genes and traits.
But the DNA sequences studied by Rosenberg and his colleagues are not genes. Known by geneticists as "microsatellite...
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