Can chemicals cause mutations in animals - People and Animals - Why Is Milk White?: & 200 Other Curious Chemistry Questions (2013)

Why Is Milk White?: & 200 Other Curious Chemistry Questions (2013)

1. People and Animals

Though Alexa’s questions are about her favorite subject, chemistry, it turns out that a lot of chemistry is involved in how people and animals react to their environment and how they grow, eat, and breathe.

Can chemicals cause mutations in animals?

Yes. But they won’t turn you into Spider-Man.

Chemicals that cause mutations are called mutagens. Mutagens cause changes in the DNA in the cells of an organism. DNA is a code that spells out how to make things in a cell. The code is made up of letters like an alphabet. Each letter represents a different chemical, called a nucleotide. There are four letters in the DNA alphabet: A, C, G, and T.

But there are some molecules that look like one of the molecules DNA uses for letters in the code. When the cell makes new DNA, it might use one of the molecules that looks like a T (for example), so that instead of spelling ACTGGTACCT, the DNA spells ACXGGTACCT. That X is the new molecule.

Usually when a spelling error like this occurs, the cell detects it and throws that DNA away so nothing bad happens. But sometimes the molecule looks so much like the real-letter molecule that it goes undetected. The misspelled word usually just doesn’t work, so the cell doesn’t make the chemical (usually a protein) it was supposed to make.

If the missing chemical is important, the cell might die, and that would be the end of it. If the missing chemical was not so important, such as something that made hair dark, you might get a gray hair instead. If the cell was a fertilized egg, all the hairs in the new animal might be white, and you get an albino, an animal that lacks the dark colors that make suntans and dark hair.

Sometimes the spelling change does make a protein, but the protein is just slightly different. It might not work as well, or it might work differently, maybe making a different color, and you get a blue frog instead of a green one.

Other chemicals might change a C into a T. Or break DNA into pieces that get put back together in the wrong order, or with a piece missing, or an extra piece added.

The likelihood of a mutation being beneficial is very small. A cell is a complicated piece of machinery, and making random changes would be like making a random change to a car engine by hitting it with a rock. The engine is unlikely to work better afterward. But occasionally a change makes the organism work better. This is evolution.