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Human
Genome
On Monday 26 June 2000, after more than a
decade of effort, a working draft of the human genome was
presented to the humanity. This day would be remembered
as the day when humankind learned about the set of
genetic instructions which governs the assembly and
fuction of human beings.
The scale of this triumph of biological
science is awesome.
The 24 different human
chromosomes may be too small for the eye to see,
but each set contains 3.1 billion base pairs: a
code written in 3.1 billion "letters".
This amount of data is equivalent to the contents
of 200 telephone directories, each 500 pages
long. It has been estimated that it would take
over nine years to read aloud this data.
If all the DNA in the human body
were put end to end, it would reach to the sun
and back more than 600 times.
There are 20 different building
blocks (amino acids ) used in an array of
combinations to produce proteins as different as
keratin in the hair and haemoglobin in the blood.
The vast majority of the DNA (97
% ) in human genome has no known fuctions.
Between humans the DNA differs by
only 0.2 %.
Human DNA is 98 % identical to
chimpanzee.
Scientists estimate that there
are 300,000 spots in the human genetic code where
individual differences can exist.
| Estimated number of genes :- Humans
& mice -60,000 to 100,000
Roundworm - 19,000
Yeast - 6,000
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Reading
Human genome code took the combined efforts of
thousands of researchers, and countless hours of
work by hundreds of state-of-the-art robotic
sequencing machines humming quietly around the
clock in pristine laboratories. Each machine
prepares DNA samples, runs them through
electrophoresis gels, and reads off the results
into a database, only requiring the help of a
human once every 24 hours. |
The public Human Genome Project
took blood and sperm samples from a dozen anonymous
donors and combined them. The project's commercial rival,
Celera Genomics, put an ad in The Washington Post,
selected 30 men and women from a variety of ethnic
backgrounds and used six of them.
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October 16, 2002
Breaking News |
| Researchers have come up with
some new findings. That the genome has revealed that the
human chromosome carries only about 30,000 genes, twice the
number of a fruit fly, 10,000 more than a roundworm, and only a
few hundred more than a mouse. Originally scientists expected as
many as 140,000, which means the question of how genes actually
work is now an even bigger mystery. The genome also reveals that
many human genes originate from microbes. This raises questions
about human evolution. |
In future : -
Doctors may treat you for
conditions such as cancer and heart disease even
before they appear. There may be fundamental
shift towards preventive
medicine.
A routine check-up in 2010 will
perhaps involve giving a sample of blood or cheek
cells, from which your DNA will be extracted and
screened to determine your risk of developing
various diseases.
We already know the genes that
cause many rare, single-gene disorders, but in
future you could be screened for common diseases
that appear in adulthood, such as type II
diabetes, heart disease and cancer, and perhaps
even complex mental disorders such as
schizophrenia and depression. Because these
diseases have many contributory factors, both
genetic and environmental, the test results will
give a percentage risk rather than a definite yes
or no.
Doctors may also use gene
screening to discover which drugs best suit you.
Our genes determine whether different drugs will
work well or cause side effects. For example,
Alzheimer's patients with a gene variant called ApoE
*4 are much less likely to benefit from a
drug called tacrine than other patients.
The insurance agencies making use
of genetic information is a possibility.
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