Anaerobic respiration

Anaerobic respiration is a way that some living things get energy without using oxygen. It is different from the way most plants and animals breathe, which is called aerobic respiration. In aerobic respiration, oxygen is the final thing that accepts electrons in a special process inside cells. But in anaerobic respiration, other substances like nitrate, fumarate, sulfate, or sulfur take the place of oxygen.

These other substances do not accept electrons as well as oxygen does, so they release less energy. This means that anaerobic respiration is not as efficient as the kind that uses oxygen. Some tiny organisms, called anaerobes, use this method to survive in places where there is no oxygen. This process is important for understanding how life can exist in environments that lack oxygen, such as deep in the ocean or in certain soils.

As compared with fermentation

Further information: Fermentation

Anaerobic cellular respiration and fermentation make energy in very different ways. In both aerobic and anaerobic respiration, special chemicals like NADH and FADH₂ help create a difference across a membrane. This difference helps make energy. In anaerobic respiration, the final thing that accepts the electrons is not oxygen but another chemical.

Fermentation, however, does not create this difference across a membrane. Instead, it makes energy by changing other chemicals directly. For example, in some bacteria, a chemical is changed to make lactic acid, and in yeast, a chemical is changed to make ethanol. These changes help reset the chemicals needed for the process to continue.

Ecological importance

Anaerobic respiration plays a big role in nature. It helps move important elements like nitrogen, iron, sulfur, and carbon around the world. This process changes these elements into different forms, which affects things like the carbon cycle and even our climate.

Anaerobic respiration happens in many places, such as water sediments, soil, deep underground areas, and even in places with a little oxygen. One important example is when tiny living things use nitrate to get energy, which helps return nitrogen to the air as gas. Another example is making methane gas, which can be a clean energy source but can also warm the planet if released too much.

Applications

Anaerobic respiration is used to clean water by removing harmful substances like nitrate and nitrite, turning them into safe nitrogen gas. This helps prevent water bodies from becoming overly rich in nutrients, which can harm aquatic life.

It is also important in cleaning up polluted environments by changing toxic chemicals into safer ones. For example, some bacteria can change harmful substances like arsenate or selenate into less dangerous forms. Anaerobic respiration can also help produce electricity in special cells called microbial fuel cells, where bacteria help turn waste into power.

Examples of electron acceptors in respiration

In some living things, they don’t use oxygen to get energy. Instead, they use other things to take in electrons. These other things are called electron acceptors. Oxygen is a very good electron acceptor, but some organisms use different ones to live and grow.