Mutations vs. Material Defects

DNA mutations have a striking similarity to defects in engineering materials. There are three main classes of both DNA mutations and defects in engineering materials (the first term is how it is referenced in biology, the second term is how it is referenced in materials science):

• singe-base-pair changes (point mutations) - point defects
• insertions or deletions of nucleotides - line defects (dislocations)
• structural rearrangements - volume defects

In DNA, point mutations usually substitute one base pair for another, such as an adenine for a guanine. In engineering materials, point defects involve substitutions of one cation for another, or one anion for another, or a vacancy*. In DNA, insertions or deletions of nucleotides change the length of the strand, and thus shift everything over; in engineering materials, line defects (dislocations) consist of a sheet of molecules being inserted into a crystal lattice (edge dislocation), which disrupts the structure of the crystal lattice and makes it effectively longer or shorter and shifts things. In DNA, structural rearrangements reshuffle the DNA sequence and effect the DNA strand on a more macroscopic scale; in engineering materials, volume defects include more macroscopic things that disrupt the structure of the material, such as twinning.

*Note that this vacancy does not disrupt the crystal structure of the material, just as a point mutation does not change the length of the DNA strand.