A set of metabolic reactions and processes that helps the organisms to convert chemical energy into adenosine triphosphate from nutrients or oxygen molecules is called cellular respiration. The catabolic reactions are involved in the respiration process that helps to break down large molecules into smaller particles.
The visual representation of the known information either in the form of graphs or charts or tables or Venn diagrams. By analyzing the meaning of the concept map we will learn the definition of the cellular respiration concept map, it is a graphic representation of the complete process of cellular respiration.
Let us see the cellular respiration map and analyze it by following the steps mentioned below.
During the process of cellular respiration, the glucose molecule is broken down into water and carbon dioxide. In the reactions that transfer glucose, some of the ATP molecules are produced along the way. But the maximum number of ATP is produced in the process called oxidative phosphorylation. A series of proteins are embedded in the mitochondria, the movement of the electrons takes place in the electron transport chain reaction during which oxidative phosphorylation occurs.
The electrons that are traveled to the electron transport chain are directly derived from the glucose molecule by some of the electron carriers such as NAD⁺ and FAD and when the gain in the electrons takes place these carriers get converted to form NADH and FADH₂. In the cellular respiration map where ever it is mentioned as “+NADh and + FADH₂”, the molecules are not being added from the scratch instead they are being converted from the electron carriers.
NAD⁺ + 2e⁻ + 2H⁺ → NADH + H⁺
FAD + 2e⁻ + 2H⁺ → FADH₂
We will see how the carbon dioxide is obtained from the glucose molecule and how the energy is harvested as NADH/FADH₂ and ATP. Cellular respiration consists of four stages, they include:
Glycolysis is the first process in the cell respiration concept map, in this process a six-carbon sugar molecule called glucose undergoes various forms of chemical transformations to convert as two pyruvate molecules at the end. The pyruvate molecule is an organic three-carbon molecule. The end product of this process is ATP and NADH which is converted from NAD⁺.
The second step that is involved in the cellular respiration concept map is pyruvate oxidation. In this process, the pyruvate that is obtained from the process of glycolysis is transferred to the innermost compartment of mitochondria called the mitochondrial matrix. In the mitochondrial matrix, each of the pyruvate molecules gets converted into a two-carbon molecule that is bound to coenzyme A called acetyl CoA. The end product of this process is the generation of NADH molecules by the release of carbon dioxide.
Citric acid cycle: The acetyl coenzyme that is obtained in the previous step of a cellular respiration mind map combines with the four-carbon molecule to undergo several cycles of reactions to obtain the regenerated four-carbon starting molecule. The final product of this process yields ATP, NADH, and FADH₂ by the release of carbon dioxide.
Oxidative phosphorylation: The NADH and FADH₂ generated in the previous steps, deposit the electron molecules in the electron transport chain by obtaining their original forms such as NAD⁺ and FAD. When these electrons are traveled down the chain the release of energy takes place and this energy is utilized to pump the protons out of the mitochondrial matrix by forming an electron gradient. To form an ATP molecule the protons are transferred back to the matrix with the help of an enzyme called ATP synthase. The end product of the electron transport chain is the formation of water with the acceptance of electrons and protons by oxygen molecules.
The final equation at the end of the cellular respiration is
Glucose + Oxygen → ATP + Carbon dioxide + Water
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If the process of glycolysis takes place in the absence of oxygen it is called fermentation. Cellular respiration includes other three steps that require oxygen, they are pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation. Among these, oxygen is directly utilized only in the case of oxidative phosphorylation, but the remaining two processes are dependent on oxidative phosphorylation for the consumption of oxygen.
The process which is used by all the living organisms in the formation of energy from glucose molecules is cellular respiration. While the autotrophs produce their own glucose molecules by the process of photosynthesis and the heterotrophs obtain their glucose from another organism. However, the process of cellular respiration is the collection of metabolic processes such as glycolysis, citric acid cycle or Krebs cycle, and electron transport chain. While moving from glycolysis to the citric acid cycle the pyruvate molecules obtained from glycolysis are oxidized by a process called pyruvate oxidation. Practice cellular respiration concept maps to understand the process easily and efficiently. Remembering the end products of each step involved is necessary as it can appear in the examination in the form of objectives.
1. What is Cellular Respiration and What are the Steps Involved in it?
The process of conversion of glucose into energy is called cellular respiration.
The steps involved are:
Citric acid cycle or Krebs cycle
Electron transport chain or oxidative phosphorylation
2. Why is Cellular Respiration Important?
Plants and animals use a process called cellular respiration to break down the larger glucose molecules to convert into energy. The converted energy is utilized in several cellular levels to perform specific functions. These enzymatic reactions occur in the mitochondria of a cell. As it involves various steps learning the concept map about cellular respiration is important to remember the process easily. The availability of glucose, temperature surrounding the organism, and the level of oxygen concentration can affect the process of cellular respiration.