Yeasts, for example spend much of their time fermenting, as do a few bacteria. The process of fermentation is an inefficient use of resources. Strict fermenters soon pollute their environment preventing themselves from growing, while their wasteful end products such as ethanol or lactate, are fuels for other cells. Chemiosmotic* cells can burn these waste products with oxygen or other substances, such as nitrate, to glean far more energy, permitting them to keep on growing for longer. Fermentation works well as part of a mix in which other cells burn up the end products, but in very limited by itself. There is strong evidence that fermentation arose later in evolution than respiration, and that makes perfect sense in light of these thermodynamic limitations.
{* What is meant by chemiosmotic?
The process of ATP synthesis using 'free energy' obtained when electrons are passed to several carriers (ETC) is known as chemiosmosis. The actual point of the synthesis of ATP takes place when electrons pass the inner mitochondrial membrane. Energy is released within this process, resulting in the synthesis of ATP.}
Perhaps surprisingly, fermentation is the only known alternative to chemiosmotic coupling. All forms of respiration, all forms of photosynthesis, are indeed all forms of autotrophy, ** where cells grow from simple inorganic percursors only, are strictly chemiosmotic. . . . . . In particular, chemiosmotic coupling is marvelously versatile. A massive range of electron sources and sinks can all be plugged into a common operating system, allowing small adaptations to have an immediate benefit. Likewise, genes can be passed around by lateral gene transfer, and again can be installed into a fully compatible system, like a new app. So chemiosmotic coupling enables metabolic adaptation to almost any environment in almost no time at all. No wonder it dominates ! Page 168
Loading
1 comment
Dinesh said:
{* What is meant by chemiosmotic?
The process of ATP synthesis using 'free energy' obtained when electrons are passed to several carriers (ETC) is known as chemiosmosis. The actual point of the synthesis of ATP takes place when electrons pass the inner mitochondrial membrane. Energy is released within this process, resulting in the synthesis of ATP.}
Perhaps surprisingly, fermentation is the only known alternative to chemiosmotic coupling. All forms of respiration, all forms of photosynthesis, are indeed all forms of autotrophy, ** where cells grow from simple inorganic percursors only, are strictly chemiosmotic. . . . . . In particular, chemiosmotic coupling is marvelously versatile. A massive range of electron sources and sinks can all be plugged into a common operating system, allowing small adaptations to have an immediate benefit. Likewise, genes can be passed around by lateral gene transfer, and again can be installed into a fully compatible system, like a new app. So chemiosmotic coupling enables metabolic adaptation to almost any environment in almost no time at all. No wonder it dominates ! Page 168