DNA is a pretty simple molecule when you consider
its awesome role in life. DNA (deoxyribonucleic
acid) gets its name from its parts.
center of every DNA molecule is a sugar called
Deoxyribose. Like other single-unit sugars, it
has 6 carbon atoms. Like all sugars I can think
of, its name ends in "ose." This sugar ring is
attached to other sugar rings by phosphate groups
to make long chains.
The reason that DNA can
carry information is because the other thing
attached to the sugar is one of 4 bases: adenine
(A), thymine (T), guanine (G), and cytosine (C).
Each base is made of different atoms, so they
interact with each other in specific ways. G and
C bond with each other and A and T bond with each
other. This makes the two chains into one double
chain that's like a ladder with the bases as the
rungs. This seems like a simple thing, but it
allows DNA to make copies of itself. That's why
DNA can be passed from one generation of cells to
Here's how it works. Suppose you
wrote "secret code" on a piece of paper, then
wrote a mirror image of each letter on another
piece of paper. If you gave the backwards copy to
a friend, he or she could make a mirror image of
each letter and be back to the original message.
If I have a string that says AATCGC, the only
bases that will line up with it will be TTAGCG.
Then when this second string is copied, it will
give me AATCGC.
Here's a good picture:
one A lined up with a C by accident (a
"mutation"), what would happen to all future
copies of this strand of DNA?
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