How is Fermentation Different from Cellular Respiration?

Both cellular respiration and fermentation ensure that healthy levels of ATP are maintained but both differ from each other in various aspects. So, how is fermentation different from cellular respiration? Read ahead to find out.
BiologyWise Staff
Before we get to the various points of difference between the two, let's first take a brief refresher tutorial of what cellular respiration and fermentation are, what they do and how they work. Cellular respiration is the process by which the cells inside the body take all the chemical or biological nourishment they need from dietary and other nutrients and convert the energy so derived into adenosine triphosphate (ATP). To make understanding easier, ATP are the molecular energy units which carry out intracellular energy transfer and these are in the form of nucleotides which are the molecular structural building blocks of RNA and DNA. The process of cellular respiration involves a catabolic reaction which breaks down nutritional molecules into smaller particles in order to make them release their locked up energy. This molecular breaking down process takes place by way of one molecule getting oxidized and another getting reduced. Oxygen is necessary for the conduction of cellular respiration.

Fermentation, on the other hand, refers to the process of extracting nutritional energy by oxidizing organic nutrients. The chief organic nutrients that flag off fermentation are carbohydrates. In contrast to cellular respiration, fermentation employs an oxidizing agent that originates within the cells and tissues of the organism in question and such an oxidizing agent is known as an endogenous electron acceptor. If you remember, cellular respiration requires oxygen which comes from outside and does not originate from within the organism's tissues. Such an oxidizing agent that is sourced from outside the body is known as an exogenous electron acceptor. That just means that fermentation can take place even when oxygen is not available. While both cellular respiration and fermentation lead to the same consequence - conversion of nutritional energy into ATP - there do exist significant differences between the two, especially in terms of their individual modus operandi. So, if you're wondering how fermentation is different from cellular respiration, just scroll down to the following segment as that's what it deals with.

Difference Between Fermentation and Cellular Respiration

While both processes result in the production of ATP and certain wastes or by-products, the differences with regards to fermentation vs cellular respiration are significant enough to attract close scrutiny and academic attention. The following points lay down the areas where both these processes differ from one another.
  • The primary point of distinction between fermentation and cellular respiration is the nature of the oxidizing agent each employs. While fermentation primarily depends upon endogenous electron acceptors, cellular respiration (which may be aerobic as well as anaerobic) almost always uses exogenous electron acceptors.
  • Aerobic cellular respiration breaks down glucose to release approximately 18 - 20 times more ATP than fermentation. Therefore, we can say that the level of intracellular energy transfer in case of cellular respiration is higher than during fermentation.
  • However, the rate of release of ATP by cellular respiration is slower than the rate of release of ATP by fermentation.
  • Cellular respiration cannot metabolize pyruvic acids in the absence of oxygen. Hence, in anaerobic conditions, pyruvic acid must undergo fermentation in order to break down into cellular waste to be, eventually, expelled from cells.
  • Fermentation can take place in the body as a means of covering up for the slow release of ATP by cellular respiration. Also, fermentation takes over the process of metabolism of organic nutrients in the absence of oxygen, when cellular respiration takes a backseat. Cellular respiration, on the other hand, cannot cover up for fermentation in vice versa situations.
So, you see, while both processes produce the same result, ATP, their respective processes and situational roles greatly differ from each other. The most common organic nutrients used for further metabolism by cellular respiration or fermentation are carbohydrates, fatty acids and various amino acids. While fermentation is the most common method of energy conversion in bacteria, yeast and other similar microorganisms, they can also undergo cellular respiration. However, in this case, the oxidizing agents tend to be inorganic in nature, such as sulfur, hydrogen, methane and metal ions and this form of cellular respiration is known as anaerobic respiration. Both metabolic processes share glycolysis as a common feature as, in both cases, individual glucose molecules are split into two pyruvate molecules. That's all there is to know about the mutual differences between both cellular energy conversion processes and fermentation. I guess that pretty much gives you a clear idea of how fermentation differs from cellular respiration. Hope you found the information useful.