Key difference - aerobic vs anaerobic breathing

Aerobic and anaerobic respiration are the two types of cellular respiration found in organisms. Cellular respiration is the process of breaking down food to release potential energy in the form of ATP . Aerobic respiration occurs in higher animals and plants. Anaerobic respiration occurs mainly in microorganisms such as yeast. Both processes use glucose as a raw material. The main difference between aerobic and anaerobic respiration is that aerobic respiration occurs in the presence of oxygen, while aerobic respiration occurs in the absence of oxygen .

This article examines

1. What is aerobic respiration - properties, process 2. What is anaerobic respiration - properties, process 3. What is the difference between aerobic and anaerobic respiration?

What is aerobic breathing?

Aerobic respiration is the series of reactions that take place in the presence of oxygen that break down food to produce energy in the form of ATP. The most common type of cell repair is aerobic respiration, which occurs in higher plants and animals. Aerobic respiration occurs in both the cytoplasm and the mitochondria . It produces 36 ATP from a single glucose molecule. There are basically three steps involved in aerobic breathing. They are glycolysis, citric acid cycle, and the electron transport chain. The substrate is mostly glucose and the inorganic end products are carbon dioxide and water. Therefore, aerobic respiration is the opposite of photosynthesis . The overall chemical response of aerobic respiration is shown below.

Chemical reaction of aerobic respiration

C ₆ H ₁₂ O ₆ + 6 O ₂ → 6CO ₂ + 6H ₂ O + 2,900 kJ / mol

Glycolysis is the first step in aerobic respiration and takes place independently without oxygen. Therefore, it is also the first step in the breakdown of glucose in anaerobic respiration. Glycolysis takes place in the cytoplasm of all cells. During glycolysis, glucose is broken down into two pyruvate molecules, creating 2 ATPs as a net gain. In addition, two molecules of NADH are formed by extracting electrons from glyceraldehyde-3-phosphate. The pyruvate is converted into the matrix of the mitochondria and forms acetyl-CoA from pyruvate by eliminating carbon dioxide during the oxidative decarboxylation of pyruvate. Acetyl-CoA then enters the citric acid cycle , also called the Krebs cycle. During the citric acid cycle, a single glucose molecule is completely oxidized to six carbon dioxide molecules, creating 2 GTPs, 6 NADH and 2 FADH ₂ . These NADH and FADH2 are combined with oxygen and generate ATP during oxidative phosphorylation. Oxidative phosphorylation takes place in the inner membrane of the mitochondria and transfers electrons through a number of carriers in the electron transport chain . The total yield of aerobic respiration is 36 ATP. A schematic diagram of aerobic respiration is shown in Figure 1 .

Figure 1: Aerobic breathing

What is Anaerobic Breathing?

Anaerobic respiration is a series of reactions that occur in the absence of oxygen that breaks food down into simple organic compounds and creates energy in the form of ATP. Anaerobic respiration occurs in microorganisms such as some bacteria, yeast, and parasitic worms. It is found in the cytoplasm of the cells of these organisms and only provides 2 ATPs.

Two categories of aerobic respiration are identified. The first category of anaerobic respiration occurs through glycolysis and incomplete oxidation of pyruvate to either lactic acid or ethanol. The process is called fermentation. The last electron acceptor and the hydrogen acceptor is the simple organic end product. The end products are secreted into the medium as waste metabolites. The first step during fermentation is glycolysis. The resulting pyruvate is converted into yeast and some bacteria into ethanol. In plants, in the absence of oxygen, ethanol is produced through anaerobic respiration. This type of fermentation is known as ethanol fermentation. The overall chemical reaction of the ethanol fermentation is shown below.

Chemical reaction of ethanol fermentation

C ₆ H ₁₂ O ₆ → 2C ₂ H ₅ OH + 2CO ₂ + 118 kJ / mol

In animals, when there is a lack of oxygen, lactic acid is produced through anaerobic respiration. This is known as lactic acid fermentation. The overall chemical reaction for lactic acid fermentation is shown below.

Chemical reaction of lactic acid fermentation

C ₆ H ₁₂ O ₆ → 2C ₃ H ₆ O ₃ +120 kJ / mol

The efficiency of fermentation is very low compared to aerobic respiration. Lactic acid, which is produced during lactic acid fermentation, is toxic to the tissues. The difference between aerobic respiration and anaerobic respiration in terms of lactic acid fermentation is shown in Figure 2 .

Figure 2: Difference between aerobic respiration and lactic acid fermentation

During the second category of anaerobic respiration, the last electron acceptor is sulfate or nitrate at the end of the electron transport chain. Some prokaryotes such as bacteria and archaea perform this type of anaerobic breathing. When electrons are absorbed by sulfate, the end product is hydrogen sulfide. In methanogens, the last electron acceptor is carbon dioxide, which creates methane as an end product.

Difference between aerobic and anaerobic breathing

oxygen

Aerobic breathing: Aerobic breathing occurs in the presence of oxygen.

Anaerobic respiration: Anaerobic respiration occurs in the absence of oxygen.

Types of plants and animals

Aerobic respiration: Aerobic respiration occurs in all higher plants and animals.

Anaerobic respiration: Anaerobic respiration is usually found in microorganisms, but rarely in higher organisms.

Appear

Aerobic respiration: Aerobic respiration only takes place inside the cell.

Anaerobic respiration: Anaerobic respiration can occur anywhere.

Localization within Cell

Aerobic respiration: Aerobic respiration occurs in the cytoplasm and in the mitochondria.

Anaerobic respiration: Anaerobic respiration only takes place in the cytoplasm.

Permanent / temporary nature

Aerobic respiration: Aerobic respiration occurs continuously in the presence of oxygen gas.

Anaerobic respiration: Anaerobic respiration takes place continuously in microorganisms. However, in higher animals it occurs in the absence of oxygen.

steps

Aerobic respiration: Aerobic respiration occurs through glycolysis, pyruvate oxidation, TCA cycle, electron transport chain and ATP synthesis.

Anaerobic respiration: Anaerobic respiration occurs through glycolysis and incomplete breakdown of pyruvate.

Efficiency

Aerobic respiration: Aerobic respiration produces 36 ATPs per glucose molecule.

Anaerobic respiration: Anaerobic respiration produces 2 ATPs per glucose molecule.

toxicity

Aerobic respiration: Aerobic respiration is non-toxic for the organism.

Anaerobic respiration: Aerobic respiration is toxic to higher organisms.

End products

Aerobic respiration: The end products of aerobic respiration are carbon dioxide and water.

Anaerobic respiration: The end products of fermentation in yeast are ethanol and carbon dioxide. In animals, the end product is lactic acid. Bacteria produce methane and hydrogen sulfide as end products.

oxidation

Aerobic respiration: The substrate is completely oxidized to carbon dioxide and water during aerobic respiration.

Anaerobic respiration: The substrate is incompletely oxidized during anaerobic respiration.

diploma

Cell respiration occurs in two ways known as aerobic respiration and anaerobic respiration. Aerobic respiration occurs mainly in higher animals and plants. Anaerobic respiration occurs in microorganisms such as parasitic worms, yeast, and some bacteria. Glucose is used as a substrate in both aerobic and anaerobic respiration. Aerobic respiration occurs in the presence of oxygen, completely oxidizing the substrate, creating inorganic end products, carbon dioxide and water. In contrast, anaerobic respiration occurs in the absence of oxygen, as a result of which the substrate is incompletely oxidized, resulting in organic end products such as ethanol. Since anaerobic respiration incompletely oxidizes the substrate, the yield of ATP is very low compared to its yield in aerobic respiration. Aerobic breathing provides 36 ATPs, but anaerobic breathing only provides 2 ATPs per glucose molecule. This is the difference between aerobic breathing and anaerobic breathing.  

Reference: 1. Cooper, Geoffrey M. "Metabolic Energy". The cell: a molecular approach. 2nd Edition. US National Library of Medicine, January 1, 1970. Web. 07.04.2017.2. Jurtshuk, Peter and Jr. "Bacterial Metabolism". Medical microbiology. 4th edition. US National Library of Medicine, Jan. 1, 1996. Web. 07.04.2017.3. Aerobic Breathing and Anaerobic Breathing - Pass My Exams: Simple Exam Notes for GSCE Biology. "Aerobic Breathing and Anaerobic Breathing - Pass My Exams: Simple Exam Review Notes for GSCE Biology." Np, nd web. 04/07/2017.

Image courtesy: 1. "Aerobic Pathways" By Boumphreyfr - Own work (CC BY-SA 3.0) via Commons Wikimedia 2. "2505 Aerobic versus Anaerobic Respiration" By OpenStax College - Anatomy & Physiology, Connexions website . June 19, 2013. (CC BY 3.0) via Commons Wikimedia