I was 13 when my grandma taught me how to bake cream puffs. Puffs are these round, hollow and slightly crispy pastries that can be filled with cream. I was an eager teenager housewife and she was an experienced baker. Nevertheless, the first round of puffs turned out a failure. The puffs did not rise, the dough had been too hot. That day I learned that some recipes must be followed to the letter, else it will not work.

Also the making of a human being requires recipes. Many recipes (about 25,000 total), which are passed down from parent to child to grandchild. This assembly of recipes is called the genome, and consists of DNA molecules that contain all the information needed to make a whole person.

Speed-course in genetics: From chromosomes via genes and protein to eye color

Grandma’s recipes were kept in a note book in her neat handwriting. DNA, however, is a filamentous molecule containing information “written” with four so-called bases, G, A, T and C. The order of these bases in the DNA strand provides the information needed to make a person. Every cell in the body has a complete copy of the genome. It’s like a recipe note book, where every recipe is found in two copies, one inherited from the mother and one from the father.

Our 25,000 genes give instructions for more than 25,000 different proteins. Each word in the recipe consists of three bases, which translates to a specific amino acid. Translation always starts at the word ATG and always ends at the word TAA, TGA or TAG. The newly produced protein chain is curled and folded up in a very specific manner to yield a mature protein, and this protein determines some property of the body, such as eye color.

It’s difficult to talk at length about the immune system, without mentioning genes and DNA. There are several reasons for this. It is not only the recipes for making a human being that is encoded by DNA. Also all the microbes we encounter have their entire recipe collections encoded as DNA, or possibly the close relative RNA. The microbes are constantly trying to escape the immune system, and the way they do it is to allow small changes in their recipes every time they are copied to produce more microbes. Sometimes such changes turn out to be disastrous for the microbe (such as with our puffs which went unsuccessful), but often a subtle change in the the recipe have no other consequence than that the immune system is tricked into ignoring the microbe.

It is also our genes that determine how the immune system works. And although we humans reproduce much, much more seldom than microbes, there will be changes in our recipes as well, that is being passed on from one generation to the next. We are actually quite different from each other, if one begins to look carefully enough. And oftentimes these differences between us are related to how our immune system works.

And yes, I inherited Grandma’s recipe collection and I still bake cream puffs. But not quite like she did. I’ve discovered that Granma’s puffs are absolutely fine also when I replace the flour with maizstarch. If I am lucky, perhaps this “mutation” of Granma’s recipe will spread to new generations of cake bakers?

Blogpost written by Anne Spurkland, 09/27/12
Translated from Norwegian 24th March 2016