Mitochondria are known as powerhouse of a cell. They are nothing, but organelles that acts like a digestive system of the cell, which takes in nutrients, breaks them up, and creates energy rich molecules to get utilized by the cell. The biochemical processes of a cell are called as cellular respiration. Many of the reactions that are involved in the cellular respiration happens into the mitochondria. Thus, we can say that mitochondria are the working organelles that keep its cell full of energy.
Mitochondria are the small organelles floating free throughout the cell. Some cells contains several thousand mitochondria while others may have none. Neurons (cells that transmits nerve impulses) don’t need) as many mitochondria. While muscle cells usually need a lot of energy for muscular works, so they have loads of mitochondria. If a cell feels that it is not getting enough energy to survive, more mitochondria can be created as per the requirement. Sometimes, one mitochondria can grow larger or also may combine with other mitochondria. It all depends upon the energy needs of the cell.
Mitochondria are shaped appropriately to maximize their productivity. They are buildup of two membranes. The outer membrane that covers the organelle and contains it just like a skin. The inner membrane folds over many a times and creates layered structures known as cristae. The fluid contained in the mitochondria is known as matrix.
The folding of inner membrane increases the surface area inside organelle. Since many of chemical reactions happens on inner membrane, this increased surface area creates more space for reactions to occur successfully. Like, if you have more space to work, surely you can get more work done.
Mitochondrion by Kelvinsong (CC0 1.0)
Most of the eukaryotic cells contains mitochondria which occupy the cytoplasm about 25%.It consist of inner and outer membrane separated by the inter membrane space. Inner membrane is impermeable whereas the outer membrane is composed of half lipid and half protein. The surface area of inner membrane is greatly increased by folding or cristae that produce into matrix.
Structure of Cristae:
The inner surface of cristae membrane is covered by infinite stalked particles calledF1 particles, elementary particles or subunits. Each F1 particles has 3 parts namely 1.Head piece 2.Stalk and 3.Base piece. The respiratory chain located in the cristae consist of enzymes and co-enzymes which constitutes the ETS(Electron Transport System).These enzymes and co-enzymes of ETS act as electron acceptors in the aerobic reaction, otherwise called as Oxidative phosphorylation.
By degradation of glucose 2 ATP molecules are produced during initial stages and at terminal stage it is 36 ATP molecules it may vary because of– energy released in mitochondria may be used for other purposes such as heat generation, transporting molecules in and out of the mitochondria.
Mitochondria using OXYGEN to release energy :
How cellular respiration does occurs in mitochondria?
The matrix is filled with proteins (enzymes) and water. Those proteins take organic molecules like pyruvate and acetyl CoA, and digest them chemically. Proteins embedded in the inner membrane releases water and carbon dip-oxide molecules from the breakdown of oxygen and glucose. The mitochondria is the only place in the cell, where oxygen is reduced and then eventually broken down into the water.
Mitochondria are also involved in controlling concentration of the Calcium ions within the cell. They works very closely with endoplasmic reticulum to limit down the amount of calcium in the cytosol.
What is mitochondrial DNA?
Although most DNA is packaged in the chromosomes within the nucleus, but mitochondria also have a little amount of DNA of their own. This genetic material is known as mitochondrial DNA or mDNA. In humans, mitochondrial DNA spans to about 16,500 DNA building blocks (base pairs), representing a small fraction of total DNA in the cells.