growing yeast

ok, so i know this is a big no no but i didnt think to many of you really read the itroductions,

ok so i have cultured many fungi, but never yeast. most of the time i am trying to get the fungi to reproduce so i can harvest the offsping, but in brewing i am tring to harvest the byprodct, alcohol. this adds a whole new element. it is mushroom growing reversed. with growing mushrooms you want you throw away the byproducts, and with brewing you throw away the fruit(yeast cultures). which leads me to my next question which im sure has allready been answered a million times, so please humor me. can i grow yeast in say a 4% sugar to water ratio to be used as an inoculnat for my brews?

Yes, but popular wisdom is to use maltose (i.e., DME) instead of sucrose for the sugar. I doubt it would make a difference over 1 generation, but over several the yeast may change to favor the simpler sugar, and its ability to ferment maltose fully would be affected. At least that is the way the legend goes.

Do a search on yeast starters.

i see the theory. i want to condition the yeast to thive on the prfered energy souce?

The first question I would ask is - do you want to grow yeast or do you want to make ethanol. Do research on aerobic and anaerobic propagation and Crabtree effect. The question is complex but the solution is simple.
bobz

+1 to what everyone else already said. And to back up what Passedpawn said, that "legend" is backed up by Jamil Zanisheff and Chris White (founder of White Labs) in their book titled "Yeast."