The Science of Genes

• Author: David Koepsell
• Profession: Author, philosopher, attorney, and educator whose recent research focuses on the nexus of science, technology, ethics, and public policy
• Pages: 30-51

Who Owns You?: Science, Innovation, and the Gene Patent Wars, Second Edition. David Koepsell.

© 2015 John Wiley & Sons, Ltd. Published 2015 by John Wiley & Sons, Ltd.

The Science of Genes

Vanessa Gonzalez and David Koepsell

3

It is clichéd, but it is fact: deoxyribonucleic acid (DNA) is the chemical basis

for all life on earth. It is a complex, long, polymer‐like compound, composed

of four nucleic acids: adenine, guanine, cytosine, and thymine. These four

nitrogen bases as they are also called are bound along a phosphate backbone

in the now‐familiar structure of the double helix.

Nucleic acids pair up with specific partners, every thymine bonds across

the “rung” in the spiral ladder with an adenine, and every cytosine with a

guanine, creating two strings bound together. Thus, by breaking the rung

and splitting the long strand of an organism’s DNA, a perfect copy of the

organism’s original DNA can be made. As seen in Figure3.1, when DNA

splits to accommodate its own duplication (replication), each of the result-

ing copies will have one parent (old) strand and one new complementary

strand, this is why DNA replication is semiconservative,1 because each

daughter cell retains only one strand from the original DNA molecule.

Long before DNA was known to exist and before it was known that it had

something to do with our behaviors, diseases, and appearances, genetics

was used in the selective breeding of agricultural products, including grains,

vegetables, and livestock. It was not until the twentieth century that DNA

was recognized as the fundamental mechanism for passing on traits from

parents to offspring.

Before we look at the relations of traits (which include many behaviors

and a good deal of what we can assume for now make us who we are as

persons) to DNA and its functioning, we will recount briefly its discovery

and trace the development of scientific knowledge about DNA to date. This

will help nonspecialists understand its role in biology and help us to begin

The Science of Genes 31

3ʹ Old

5ʹ Old

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AT

A

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5ʹ New

3ʹ New

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Figure 3.1 DNA double helix and semiconservative replication. One new strand

and one old one encompass the double helix of daughter cells.