How Does DNA Work?
DNA is a chain built up of four simple building blocks. The four
types are adenine, cytosine, thymine and guanine or A, C, T and G for
short. The shapes of A and T and of C and G are "complementary".
Each of the two pairs fit together neatly like pieces of a jigsaw
puzzle. The two chains of the DNA structure stick together due to
bonds which form between the complementary pairs of bases. It is the
complementary base pairs that allow DNA to copy itself.
Under certain circumstances the two chains of the DNA molecule
separate. New DNA bases come in and stick to their complementary
partner on the existing chain. The new bases are then stuck together
to make a "daughter" DNA chain. This process occurs for each of the
original chains of the parent DNA molecule. Two daughter DNA chains
are, therefore, formed.