Pin Me

Understanding the Chemical Equation for Anaerobic Respiration

written by: Destiny Keller • edited by: Amanda Grove • updated: 1/5/2012

What is anaerobic respiration? How does it work? What is the chemical equation for it? Use this study guide to discover more.

  • slide 1 of 6

    It's in the Equation

    Glucose = (ethanol or lactic acid) + carbon dioxide + energy

    C6H12O6 = 2C2H5OH + 2CO2 + 2ATP.

    Anaerobic respiration is the ability of an organism to produce energy in the form of Adenosine Triphosphate (ATP) without using oxygen. Instead, sulfate, nitrate or sulfur is used. To break down the equation above, organisms that use anaerobic respiration to produce energy start with glucose. Glucose is sugar, and the same sugar from the photosynthesis equation 6CO2 + 6H20 = C6h1206 + 6 02. Organisms take glucose, and through the electron transport chain, produce ethanol or lactic acid and CO2, and ATP.

  • slide 2 of 6

    How Does Anaerobic Respiration Work?

    Even humans and animals use anaerobic respiration for short periods when they have a low supply of oxygen. To understand this, think of a runner on a track field. As they take off and sprint, it takes a while for aerobic respiration to start up because it takes a few seconds for increased amount of oxygen they need to get into their muscle cells.

    During this short time, anaerobic respiration is used to make ATP to fuel your muscles as they run. This form of respiration is not favorable, as only 2 ATP are produced, compared to aerobic respiration, which forms 36 molecules of ATP per molecule of glucose. Anaerobic respiration can also be unfavorable due to the side products it produces. Most humans and animals produce lactic acid as a byproduct of anaerobic respiration.

    This is toxic when it builds up in cells and can be felt as a burning feeling in muscles as they fatigue. Thankfully, anaerobic respiration only lasts a maximum of twenty seconds, afterwards which aerobic respiration usually takes over.

    The build up of lactic acid leaves us with oxygen debt. This is thought to be why a person needs to take a minute to catch their breath after an intense exercise such as a sprint. In order for lactic acid to be broken down so it is no longer harmful to the cell, more oxygen must be used to break down lactic acid.

  • slide 3 of 6

    How does this Apply to Sports?

    Many athletes take advantage of this type of respiration as it helps with short bursts of energy. They can train to lengthen the time anaerobic respiration goes on in their cells, and increase the amount of lactic acid they can build up. Training usually consists of high intensity exercises such as jumping or sprinting for a short period of time repeatedly.

    Over time, a person can lengthen the amount time their body spends on anaerobic metabolism. This can be useful in sports such as baseball, or football, where plays are short and intense.

  • slide 4 of 6

    What about Ethanol?

    The other byproduct some organisms produce in the chemical equation for anaerobic respiration is ethanol. Organisms such as yeast can continuously do cellular respiration aerobically or anaerobically. When an organism can switch between these two forms of respiration, they are known as facultative anaerobes. When an organism can only respire without oxygen, it is known as an obligate anaerobe. Organisms that live this way are usually bacteria.

  • slide 5 of 6

    Aerobic Respiration

    Glucose + Oxygen = Carbon Dioxide + Water + Energy

    C6h1206 + 602 = 6CO2 + 6H20 + 36 ATP

    Aerobic respiration produces much more ATP as it goes through glycolysis and the electron transport chain. Think back to the runner now doing a mile long run. His body will switch over and aerobic respiration to give his muscle cells the energy they need to function properly, since anaerobic respiration lasts only about 20 seconds max. Since the runner is breathing oxygen and not building up lactic acid, he can go for a longer period of time as aerobic respiration can keep going.

  • slide 6 of 6


    Equation of Anaerobic Respiration:



    Cellular Respiration: