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Advances in DNA Testing(Read
This Article Carefully)
˜Change
is the only constant, - so the saying goes. Nowhere is this truer
than within the realms of bio-analytical science... it's quite remarkable
to see how much things can, and do, change. In the 50 or so years
since the structure of DNA was revealed, mankind has progressed
by leaps and bounds in developing new applications, from DNA fingerprint
profiling and Dolly the cloned sheep, to personalised drug development
based on the genetic make-up of an individual.These discoveries
are not restricted just to academia or medicine but are now transferring
across a range of industries, with a significant increase in the
commercialisation of DNA fingerprint profiling within the legal
services community. The last decade in particular has highlighted
the power of DNA profiling as an indispensable tool for human identity
and relationship testing.
What is DNA? In essence, DNA is the biological molecule responsible
for making you you. It acts as a memory chip, as it were, storing
all the information required to build living organisms, from plants
and flowers to dogs and humans. DNA is a complex biological molecule
consisting of 2 intertwined strands, forming a double helix. Each
of the strands is made up of four major individual components called
nucleotides. These nucleotides adenine, thymine, cytosine, and guanine
are enough to encode all the genetic information of an individual,
and it is the order in which the different nucleotides are arranged
that determines the function of the genes.
On average, human DNA contains 3.5 billion nucleotides, encoding
an estimated 30,000 genes in every cell. There are approximately
100 trillion cells in the human body each containing DNA. This means
that if you were to unravel your entire DNA and line it up, it would
be enough to reach from the earth to the sun and back about 70 times
over. Development of Genetic Theory Throughout history people have
been intrigued by the mechanism of inheritance. From as early as
400BC Hippocrates speculated that "seeds" were produced
by various body parts and transmitted to offspring at the time of
conception. Across millennia various theories sprang up and died
down, but it really wasn't until the 19th century that a consistent
theory began to form. In 1865 Gregor Mendel hypothesised that the
phenomenon of the inheritance of certain characteristics is due
to transferable elements'; the gene.
Hence, we have Genetics as the study of Inheritance. In 1869, independently
of Mendel but unknowingly in a field related to his work, a Swiss
biochemist Friedrich Miescher was the first to isolate nucleic acids,
the molecular substrates of the genetic code. As time went on more,
people contributed to our understanding of DNA and inheritance.
However, the next major breakthrough came in 1953, when James Watson
and Francis Crick discovered the structure of DNA and were able
to demonstrate how genetic information encoded in DNA could be passed
on from generation to generation. Watson and Crick showed that the
DNA molecule is a double helix, which consists of two intertwined
DNA strands. The culmination of these works led to what we know
of the structure of DNA and the mechanism of its action. But even
after knowing the structure, it wasn't until the mid 1980's that
the power of DNA analysis for identification purposes was revealed.
In 1984 Leicester university professor Alec Jeffreys developed a
technique which was to revolutionise both human identity and relationship
testing - The DNA Fingerprint.
As with conventional fingerprints, where various loops and ridges
are compared between individuals, DNA testing relies on comparing
certain DNA features called DNA markers, between two (or more) DNA
samples, and studying similarities between them. The very first
case that utilised DNA fingerprinting was Sarba vs. the Home Office,
1985, an immigration case where it was necessary to prove the direct
biological relationship between Christianna Sarba and her son Andrew.
By comparing Christianna's DNA sample against that of Andrew's and
his three legally recognised siblings, a direct biological relationship
was shown beyond a doubt.
The power of this analytical technique was again demonstrated the
following year, when it was used in the Enderby Murder investigations,
1986. Biological samples left on the victim and at the crime scene
were collected and analysed, and then compared with the sample provided
by the suspect, a man that had allegedly confessed, however the
samples didn't match. This sparked the first DNA man-hunt, and after
comparing nearly 2,000 samples the perpetrator, a man called Colin
Pitchfork, was found and convicted. So in this case DNA evidence
not only helped to incarcerate the criminal, but it also exonerated
an innocent man. And the science continues to evolve. Today we can
not only identify an individual by a single cell, but also obtain
information from DNA testing about their sex, ethnic background,
medical history, and even establish complex relationships such as
grandparentage, cousinship and ancestry. Within the next couple
of years it may be possible to tell an individual age, and who knows
what lies beyond?(Author)
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