For use with Chapter 15
Human Heredity
Cracking the Code
Posted on February 7,2000
Last month, scientists made a huge step in our understanding of human
biology. Members of the Human Genome Project (HGP) successfully completed
the sequencing of the first human chromosome, chromosome 22. To do this,
scientists had to decode the 33.5 million chemical components of the
chromosome. Only 97 percent of the chromosome has been decoded, but
scientists consider it complete for now.
The Human Genome Project is a $3 billion research project begun in 1990.
It is planned as a 15-year project to crack the code of all human genes.
Scientists hope that once the whole human genome is sequenced that we can
predict certain disorders - and even eventually cure or prevent them.
Chromosome 22 holds the genes connected to many different genetic
disorders. There are more than 30 disorders associated with chromosome 22,
including a form of leukemia, disorders in fetal development, and
schizophrenia. Scientists chose this chromosome as the first one in the
HGP because it is one of the most densely packed.
"For the first time we can see the entire landscape of a human chromosome,
the basic unit of human inheritance, how the genes are organized, how they
are laid out on the chromosome," said Dr. Francis Collins, chair of the
National Human Genome Research Institute.
Humans have 23 pairs of chromosomes, each one containing thousands of
genes. It is estimated that 80 000 genes are encoded in our 46
chromosomes. Scientists on the HGP will need to identify the 3 billion
base pairs in the human DNA of each cell, so they definitely have their
work cut out for them.
Now that the first chromosome has been sequenced, scientists are estimating
the remaining chromosomes will be decoded quickly. The next in line is
chromosome 7. Scientists on the HGP estimate that they could have this
next chromosome sequenced as early as next spring.
Activity
Use the Internet to learn more about the Human Genome Project. Write an
entry in your science journal explaining the objectives of this project and
how it is progressing.
References
Scientists Sequence First Human Chromosome. http://cnn.com/HEALTH/12/01/chromosome.22/
National Human Genome Research Institute. http://www.nhgri.nih.gov/
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