Along with the 5 (and possibly more) taste qualities we all had to memorize at some point, we also had to memorize the taste map of the tongue (yes... I know umami is missing):
Well... what a waste of time to memorize the tongue taste map because it is wrong!!! This tongue taste map was originally sketched by Edwin Boring in 1942 and has since been frequently reproduced in textbooks, wine classes, and biology courses.
The tongue taste map delineates specific areas where certain taste qualities are perceived better than in other areas like the state of Texas is distinctly a different region than Montana.
However, reality is a mish-mash patchwork spread unevenly throughout the tongue that is different for each person.
Each of the ~5000 taste buds found on the surface of the tongue contain clusters of over 100 taste cells with receptors that have different degrees of sensitivity to molecules carrying MORE than one basic taste and that these clusters are distributed across the entire surface of the tongue.
Tongue taste map is a lie.
The cell biology of taste. JCB vol. 190 no. 3 285-296, doi: 10.1083/jcb.201003144
Receptor seeks ligand: on the way to cloning the molecular receptors for sweet and bitter taste. Nat. Med. 5:381–382. doi:10.1038/7377
A Map of Taste. NYT 3/19/12