What are genes?

The human body is built from billions of cells that together make our tissue. Each individual cell carries an entire genetic blueprint, which steers the various characteristics and mechanisms of our body. In particular, these genes determine the color of our eyes and our hair or how tall we will be.

This blueprint is the located on 23 chromosome pairs composed of DNA (deoxyribonucleic acid). Like the individual letters in the text of a book, the codes in our DNA are single chemical building blocks, the so-called bases, of our entire genetic information. In human DNA there are four different bases: adenine, thymine, guanine and cytosine. The base pairs are always built between adenine and thymine and guanine and cytosine. The human genome (that is the totality of genetic information) holds about three billion base pairs. If the genetic information of person to person only slightly differs, each person’s DNA (with the exception of identical twins) is still entirely unique.

Genes for Taste

Genes have not only the ability to influence external characteristics such as hair and eye color; they can also determine differences such as the senses of taste and smell. This means that the sensitivity to the perception of taste is genetically determined and individually different. One of the most important factors is the number of taste cells that are found on the tongue. These can differ between super tasters with about 425 taste buds, normal tasters with about 180, and non-tasters with about 100 taste buds per square centimeter. Super tasters experience tastes much more intensely, particularly bitterness, but also spiciness. The sense of taste significantly influences the choice of food and therefore also the eating habits of a given person.

Flavors interact with corresponding receptors in the oral cavity: so-called TAS1 receptors (TAS stands for taste) function as calorie sensors and recognize animal protein in addition to carbohydrates such as sugar; TAS2 receptors recognize bitter substances. The genetic variability of TAS2 receptors leads to the differences in perception, for example, with the bitter substances Phenylthiocarbamid (PTC) and Propylthiouracil (PROP). The differences here are due to the TAS2R38 variants of the bitter taste receptor genes. Seventy percent of Europeans perceive this substance up to 1000 times better than the rest of the thirty percent of the population. Twenty five of the TAS2R genes responsible for bitterness perception have already been decoded, but there are still additional variants (haplotypes). There may be thousands of differences in bitter substances in nature that can be tasted with various levels of perception, more or less intensely, depending on the genetic makeup. The genome determines the constitution of the receptors on the tongue. When a specific bitter substance does not match with the form of the receptors on the tongue, a taste cannot be perceived.

We took only one of the 25 TAS2R genes under the microscope, thus analyzing only a single tasting receptor type. In other words, there is a great potential for information which still has to be researched.

Fig. 1 The humane TAS2R family