Yeast

 I woke up in the middle of the night, and spent two hours going

back and forth and between languages in Wikipedia. I think

I have finally done it: given myself an overview of the terrain in 

biochemistry. I've wanted to do this for a long time but have

always been put off by all those terms, concepts and complicated

diagrams. 

I've found a way in: alcohol, the topic: fermentation. the

researcher: Pasteur in the mid 19th century who published "...About Beer". 

But first, one needs to go back to an earlier scientific mind, the German

Theodor Schwann(1810-1882), who developed very powerful microscopes.

He recognized that fermentation was the work of tiny organisms

'whose structures resembled those of plants'. He coined the term

metabolism.

Building on this, Pasteur found that fermentation needed to occur in the

abscence of oxygen. Today we recognize that it is a method to get energy

from molecules, and the oldest metabolic pathway on Earth, dating back

to a time when there was no oxygen. Eduard Buchner(1860-1917)

won a Nobel Prize in 1917 for showing it was a substance produced by yeast

that caused fermentation, in effect enzymes.

A yeast is a 'mushroom' that reproduces by budding.