I know when I started getting into the world of wine, the question always came up as to how they got all those flavors into the wine. It took awhile for me to not only figure out how the flavors suddenly appeared in a wine, but also how one particular wine had more flavors than another. Today, I found an exciting BBC article (depending on your interests) as to how we taste sweet and bitter.

Our ability to distinguish between sweet and bitter tastes may reside in the same taste bud cells, say US scientists.
Cells in our tongues sense four basic tastes – sweet, salty, sour and bitter – plus salts of certain acids. ([umami->http://en.wikipedia.org/wiki/Unami])
Read more here: BBC SCIENCE

For a good animation on the basics of taste check out this: [How taste works->http://www.bbc.co.uk/science/humanbody/body/factfiles/taste/taste.shtml]
And for the ultimate in learning about flavors in wine, check out this site. Here you will learn all about each flavor you taste in your next bottle of wine. Incredibly detailed, and very well researched, make sure to bookmark this page for future reference.
What are those flavors in my wine?