What is cellular respiration? – What it is, stages and types
Cellular respiration is one of the most important processes for organic life and an essential one for metabolism. It is composed of a series of complex stages that are closely related to organic chemistry, although this process goes far beyond this area.
For all this, knowing each step that makes up what cellular respiration is is of the utmost importance and, in this sense, we bring you this article, where we will review a little what cellular respiration is and which is the main function it plays in cells, as well as its different stages. Join us to learn more about this topic!
Meaning and concept of cellular respiration
Cellular respiration is a process consisting of several steps in which the particles are charged with energy, taking sugars or organic molecules to react with oxygen componentssuch as carbon and hydrogen. As products resulting from this process are water, carbon dioxide and adenosine triphosphate (ATP).
These chemical reactions take place in the cytoplasm and mitochondria, and are processed by specific enzymes that drive each reaction. Some organic compounds are completely broken down by oxidation, resulting in inorganic substances that provide energy to the whole cell, allowing it, in such a way, to carry out all the vital functions.
During the process of cellular respiration the inorganic substances obtained specialize in providing energy. The cell can make 100% use of this energy to carry out its functions more efficiently, in addition, it reserves a part of this energy so that the process can be repeated in the future. which allows you to carry out your metabolic and physiological processes successfully.
The cell removes carbon dioxide through the breathing, being ATP the necessary molecule for the cell to recharge itself with chemical energy and to be able to carry out its functions. During the process, the cell will always store a small part of the energy to repeat the process in the future.
Cellular respiration is a life process in cells, because it allows its proper functioning and is essential for life. Through cellular respiration, cells obtain the energy necessary to carry out all vital functions and maintain the internal balance of the cell.
What is plant cellular respiration?
Plant respiration is the opposite process to photosynthesis in plants. During this process, oxygen and glucose are transform into components of CO₂ and waterreleasing energy stored in carbohydrates in a constant and exothermic way without the need for sunlight, unlike photosynthesis, which is a process that does store energy and is endothermic.
Unlike the photosynthetic cells present in the leaves, the stem and root cells do not have photosynthetic pigments, so they must seek other mechanisms to obtain energy. Leaf cells contain chlorophyllwhich allows them to absorb sunlight and participate in photosynthesis.
When cells are not constantly exposed to sunlight, their main source of energy comes from their energy reserves, mainly in the form of of starch. To make the most of this stored energy, cells break down starch molecules into glucose, which is then transported to cells for use in metabolic processes. In plants, this process occurs within mitochondria during cellular respiration.
Unlike photosynthesis, cellular respiration does not require the use of catalysts. Some reactions occur due to the presence of chlorophylland the process takes place in the cytoplasm of cells.
What are the characteristics of cellular respiration?
Cellular respiration is a process essential for the obtaining energy in the cells of living beings. It takes place in the mitochondria and is a catabolic process that uses different substrates as fuel.
The main features of cellular respiration are:
- It occurs within the mitochondria.
- It is a catabolic process that is part of metabolism.
- The energy is retained in the substrates used as fuel.
- The release of energy is done in a controlled manner.
- During the cycle, exothermic reactions take place that incorporate energy into ATP molecules and nucleotide triphosphates.
- The substrates used are mainly organic compounds such as glucose, carbohydrates, amino acids, fatty acids and ketone bodies.
- In animals, fuels come from food obtained in digestion or from body reserves.
- In plants, the resulting glucose of photosynthesis is an important part of the substrates used in cellular respiration.
This process of cellular respiration is vital for obtaining energy in living beings. In fact, thanks to this process, the ATP molecules that provide the necessary energy to carry out different cellular functions. Understanding the characteristics of cellular respiration is a fundamental issue to understand the functioning of living organisms and the cellular machinery that makes up each one of us.
What type of metabolism is cellular respiration?
During the entire process of cellular respiration, one speaks of a type of metabolism called catabolismsince glucose is broken down through these steps to release energy that will be used in cellular reactions.
Therefore, we can say that cellular respiration is a catabolic process.
What is the organ that performs cellular respiration?
The organ responsible for carrying out cellular respiration in eukaryotic cells are the mitochondria. It is here where the degradation of organic compounds to obtain energy occurs and, therefore, those cells that require a greater supply of energy will have a greater number of mitochondria.
The mitochondria are made up of two membranes, where the external one is smooth and the internal one presents ridges on its surface. In cells that require a greater amount of energy, such as muscle cells, the cristae take up most of the space, which reduces the space for matrix.
In the inner zone of the mitochondria, near the cristae, is the stromawhich contains enzymes, phosphates, water, coenzymes and other molecules involved in cellular respiration.
The inner membranes of the cristae are composed of 20% lipids and 80% proteins, mainly molecules of pyruvic acid and ATP. These proteins function as selective barriers to restrict the passage of other molecules and thus maintain the efficiency of the respiration process.
In the Krebs cycle, the enzymes act on the mitochondrial matrix during electron transport in cristae membranes.
Where does cellular respiration take place?
In eukaryotic cells, cellular respiration occurs within the mitochondria. In prokaryotic cells, on the other hand, it is carried out in respiratory structures present in the plasmatic membranes.
What are the stages of cellular respiration?
The reactions that take place during cellular respiration are established in three cycles:
Also known as glycolysis, is the first phase that originates within the cytoplasm of most cells. Here the glucose molecule, which has six carbons, is converted into two pyruvate particles, each with three carbons.
This process consists of ten catalyzed reactions entirely by one enzyme. Two cells of ATP are consumed to create another four, and two hydrogen-carrying molecules for later use are also generated.
Also called citric acid cycle or tricarboxylic cycle, this phase of cellular respiration occurs in the mitochondria of eukaryotic cells and produces carbon dioxide. This carbon dioxide is removed to make way for electron-carrying molecules, which then move on to the next stage.
This is the final phase of cellular respiration, in which the main element is oxygen. The electron carriers from the previous stage, NADH and FADH2, leave their electrons as sequence proteins that insert into the inner membrane of the mitochondria.
Electrons are converted into oxygen molecules to combine with hydrogen to produce H2O. A phosphate group is then added to create ATP. This last step is known as phosphorylation.
types of cellular respiration
exist two types cellular respiration, which are differentiated by the presence or absence of oxygen:
This type of respiration is what occurs in most organisms, including humans. During aerobic respiration, the final electrons combine with molecular oxygen and are reduced to water. Organisms that perform this type of respiration are called aerobic.
The process begins with glycolysis, where sugars are broken down to produce energy. Then the resulting pyruvate transported to mitochondria in eukaryotic cells, where it is converted to carbon dioxide. This is removed from the body and the Krebs cycle begins.
In anaerobic respiration, the end result is an inorganic molecule and no oxygen is used. This type of respiration occurs in the mitochondria, where pyruvate breaks down through certain fermentation processes. Anaerobic respiration produces less energy compared to aerobic respiration that requires oxygen.
It is amazing how these compact processes of cellular respiration occur within organisms as small as cells. Each stage is essential to obtain the best results and the power take thus becomes very important structures.