Mitochondrial DNA or mtDNA is the deoxyribonucleic acid present in the mitochondria organelles. This DNA was discovered by Margit and Sylvan Nass via electron microscopy. The discovery enabled an understanding…
Are you looking for information on mitochondrial functions? This BiologyWise article the structure and function of mitochondria with the help of a labeled diagram.
The study of cell organelles and their functions covers individual responsibilities of each subunit of a cell – each organelle is a structure within a cell that has a specific function. Among the many organelles that make up an eukaryotic cell (cells that have a nucleus), is mitochondria – the powerhouse of the cell.
Cellular mitochondria is made up of a double layered membrane, the inner part of which is made up of folds called cristae. Mitochondrial functions are not limited to just the generation of Adenosine Triphosphate (ATP) though this is one of its most important responsibilities.
As all the organelles of a cell work cohesively to perform bodily functions, mitochondrial function in a cell are manifold.
Each cell organelle is uniquely designed to support its functions, as can be seen in mitochondria structure and functions. A mitochondrion is made up of two membranes: an outer membrane and an inner membrane, both made up of proteins and other complex compounds. Since both membranes have distinct properties, a single mitochondrion is made up of the intermembrane space, the crista space, and the matrix, apart from the two membranes. Each part of the organelle has an important role to play, and the structure of each mitochondrion is instrumental in the performance of these.
The outer membrane is the housing for various components of mitochondria and is permeable to ATP, ADP, or other molecules. The inner membrane consists of molecules of electron transport system in addition to transport proteins and various complexes. It is less permeable than the outer membrane. The matrix is cytoplasmic and consists of the DNA molecules in addition to various gases and enzymes. Ribosomes are responsible for synthesizing proteins and are contained in the matrix along with other complexes. The cristae are the introversions which are responsible for increase in the surface area of the inner membrane.
Production of Energy
The primary mitochondrial function in animal cells is the production of energy in the form of ATP, and the regulation of cellular metabolism. The reactions that are involved in the production of ATP are collectively known as the Citric Acid Cycle or Krebs Cycle. Once food is broken down into its component parts by the process of metabolism, the food molecules are transferred to the mitochondria where they undergo further processing through the Krebs cycle to produce energy, after a number of complex reactions, in the presence of oxygen.
Programmed Cell Death
Another important function of note is the role of mitochondria in apoptosis, or programmed cell death. This is carried out by an organism in the developmental stage when there are unwanted cells that need to be destroyed – for instance, it is this apoptosis that enables the digits of the hand to separate into fingers during fetal development. It is also carried out when the body detects infections, or as an immune system response to bacteria or an illness. Since oxygen is required for the production of ATP, in conditions where the body is combating an illness, the consumption of oxygen rises, as a result of which certain mitochondrial reactions cause the production of free radicals. Free radicals, in excess of the mitochondria’s ability to detoxify the cell, cause damage to the mitochondria. Abnormal cell death due to malfunction can give rise to medical conditions or interfere with the organ functioning.
Mitochondrial functions also include the following:
✛ Building, breakdown, and recycling of products that are needed for the cell to function normally
✛ Formation of parts of blood and hormones such as estrogen and testosterone
✛ Synthesis of steroids
✛ Regulation of membrane potential
✛ Monitoring of cell differentiation, growth, and development
✛ Cell signaling of neurons
Understanding the role of mitochondria, is not purely academic – a mitochondrial function test, called an ATP Profile Test can be used to diagnose Chronic Fatigue Syndrome, or CFS, which has been linked to mitochondrial failure or inefficiency.