DNA

DNA or deoxyribonucleic acid is a highly complex and
intriguing chemical. It consists of five chemicals, a sugar
phosphate base, as well as adenine (a) , thymine (t) , guanine
(g) and cytosine (c). The last four chemicals are the most
important. They are called bases, and the order in which they
are sequenced along a DNA strand is vital, these sequences
can last for hundreds or even thousands of bases. What is
contained in these bases is the information needed to make a
protein (see section entitled genes), so therefore DNA contains
the information to live. DNA is formed in the shape of a
double helix (See FIG. C) and each base on one side has a
corresponding base on the other side. Adenine is always
paired with thymine, and vice versa, while cytosine is always
paired with guanine and vice versa, no one is quite sure why
this is. In order to give the information needed to make a
protein to the mRNA (see section entitled genes) the DNA first
unwinds a portion of itself and then the bases that hold the
information break out from the DNA and join up with the
mRNA. In order to fill in the empty spaces, free bases floating
in the nucleus (referred to as nucleotides) attach to where the
other bases used to be and soon the DNA is back to normal.