I often think about yeast, although probably less often than I think about products that are a result of the action of yeast! The main use of yeast is for us to utilise two of the side products of fermentation. Carbon Dioxide and alcohol. Of course some of my favorites use both ( basically Champagne, not alcoholic bread!)
I have even been known to use yeast as an illustration of the perfection of Creation, God has used evolution to develop an organism of such utility it is hard not believe that it is part of a plan. In bread yeast gives us the texture that makes bread good to eat, and in the cooking the alcohol is destroyed. On the other hand fermentation makes dirty water safe to drink (the origin of beer was to find a safe way of drinking impure water), yet when the alcoholic strength of beer or wine rises to a suitable level the alcohol itself kills the yeast which will then settle out to the bottom of the liquid. I know this is a little like the Babel Fish argument but basically I don't care!
One of the things about yeasts is that it penetrates into every part of grape juice, or dough, that way it can change every bit of it, Jesus recognises this when he warns his disciples against the "Yeast of the Pharisees" and Paul uses the same illustration in 1 Corinthians when he encourages us "Don't you know that a little yeast works through the whole batch of dough? Get rid of the old yeast that you may be a new batch". There are aspects of our lives that are like yeast and do work through everything that we do and are. For me I want my faith to be like yeast, Christianity is not something I do on a Sunday morning, to be of any real truth it has to be something that penetrates every aspect of my life, there can be no areas where I am not Christian, nowhere where I should not talk about my faith, no time when I am not a witness to Christ's love.
In the much same way, since starting my transition I cannot (or at the very least will not) deny being trans, while I accept that everything is not about gender, it does influence and inform everything that I do. I may not wear a Tee Shirt proclaiming myself as a Trans Woman but the realisation that that is what I am touches everything about my life, just like yeast permeating all of the dough.