Subject: Can pyruvate replace glucose in the process of respiration?

I'm confused about whether another substrate can be used for the process 
of respiration.  I know that fructose and sucrose will enable the process 
of respiration to occur, but will pyruvate alone serve as a substrate? 
Pyruvate is an intermediate in the process of respiration, so shouldn't 
this mean that it will serve as a means to replace glucose? Also, when 
there's no glucose available, cells turn to fat reserves, so doesn't this 
serve as another substrate?  So why can't pyruvate be utilized in the 
respiration process alone, without the presence of glucose? (the only 
other substances being present being yeast and water)

Re: Can pyruvate replace glucose in the process of respiration?