Mitochondria

Introduction: 

Mitochondria are unique organelles in human cells that act as a powerhouse. They perform a variety of other critical biological functions and are necessary for the proper functioning of the living cell. The mitochondrion consists of such a membrane that allows most molecules to pass through and an inner membrane that is firmly shut. Mitochondria can merge and split, forming large, dynamic networks within the cell. These are in charge of extracting energy from meals via cellular respiration. 

Mitochondria were first found in 1857 by the physiologist Albert von Kolliker and referred to as “bioblasts” (life germ) by Richard Altman in 1886. Twelve years later, Carl Benda changed it to “mitochondria.”

Structure of mitochondria

Mitochondria have two membranes, one is inner, and the other one is outer, separated by an intermembrane gap. Porins are proteins found in the outer membrane of the mitochondrion that allows ions to flow in and out. The outer membrane also contains enzymes involved in the extension of fatty acids and the oxidation of adrenaline.

The matrix is a region within the mitochondria’s inner membrane that includes Krebs and fatty acid cycle enzymes, as well as DNA, RNA, ribosomes, and calcium granules.

Several enzymes can be found in the inner membrane. It comprises transportation proteins that control the passage of metabolites inside and outside of the matrix, as well as ATP synthase.

The inner membrane is divided into cristae to improve the surface area accessible for oxidative phosphorylation energy production.

Functions of mitochondria

The 10 functions of mitochondria are:

1. Energy production – The citric acid cycle, often known as the Krebs cycle, is responsible for the majority of ATP production in mitochondria. Mitochondria are organelles that transfer chemical energy from the food we eat into a condition that the cell could use. This is known as oxidative phosphorylation.
2. Dead cell removal – Apoptosis, or cell death, is an inevitable aspect of life. Cells are cleaned away and destroyed as they get old or broken. Mitochondria decide which cells are killed. Mitochondria produce cytochrome C, which triggers caspase, one of the most important enzymes involved in apoptotic cell death. Mitochondria are assumed to have a role in disease because certain disorders, such as cancer, include a breakdown in regular apoptosis.
3. Storing calcium – Calcium is required for a variety of biological functions. For example, releasing calcium into a cell can cause a nerve cell to release a neurotransmitter or endocrine cells to release hormones. Calcium is required for a variety of functions, including muscular function, fertilisation, and blood coagulation. Calcium is so important to the cell that it is tightly regulated. Mitochondria help in collecting calcium ions and storing them till they are required. Calcium also has a function in cell signalling metabolism, steroid production, and hormone signalling in the cell.

4. Producing heat-  The body can also create heat in various ways, one being through the use of brown fat, a type of tissue. Mitochondria can create heat through a mechanism known as a proton. Non-shivering thermogenesis is the term for this type of thermogenesis. Brown fat levels are highest in infants, when we are most vulnerable to cold, and gradually decrease as we become older.
5. Immunity regulation- The inborn mechanism that recognises and responds to pathogen infection, providing prompt, non-specific defence, which is known as innate immunity. MAVS (mitochondrial antiviral signalling protein) aids in the induction of antiviral and anti-inflammatory pathways in the immune reaction to viral infections.

6. Oxidation- They use oxygen to convert water and carbon dioxide from carbohydrates and lipids in the cell. A part of the energy released by oxidation is used to make ATP. The mitochondria are known as the cell’s powerhouse because it produces the energy-rich chemical ATP.

7.  Mitochondria are considered semi-autonomous organelles since they may produce some of their very own proteins.

8.  Mitochondria are also involved in cellular division, cell signalling, cellular senescence, directing the cell cycle, and cell proliferation, among other things.

9.  It is responsible for the formation of some blood components as well as hormones such as testosterone and oestrogen.

10. Tries to encourage the formation of new cells and the multiplication of existing ones. Aids in the detoxification of ammonia in liver cells.

Mitochondria, also known as guardians of cell life and death, simultaneously control apoptotic and necrotic cell damage; therefore, disruptions involving these pathways can result in untimely cell death. Inappropriate tissue growth and the growth of tumours, which are likewise characterised by abnormal mitochondrial metabolism, might result from a lack of adequate cell death. The importance of mitochondrial malfunction in a surprising number of significant human diseases is gradually becoming recognised, opening the door to novel treatment methods to treat different types of unpleasant and common diseases.

Conclusion 

Mitochondria are cellular structures that carry out oxidative phosphorylation, which is the process of turning nutrients into ATP molecules, which are used to power regular cell operations. Cells die as a result of widespread mitochondrial damage since they can no longer create adequate energy.

                      Mitochondria are the offspring of bacteria that colonised primordial eukaryotic cells and evolved into energy plants for their new hosts.