Mitochondria are found in all eukaryotic cells and play an essential role in cellular respiration. They produce adenosine triphosphate, the cell’s main energy carrier. They also regulate a number of metabolic pathways and cell death.
The mitochondrial outer membrane (OMM) separates an inner mitochondrial matrix from a dilute intermembrane space. The OMM contains inward protrusions called cristae that increase surface area.
They are essential for cellular respiration
The mitochondria of a plant are essential for cellular respiration, a process that produces energy from organic molecules. This energy is used to build cells and to create proteins. The process also releases carbon dioxide, which is exhaled with each breath. The energy for this process comes from the breakdown of glucose, a form of sugar. The energy is released through a series of chemical reactions that converts the glucose into adenosine triphosphate (ATP).
Mitochondria are small organelles that are found in almost all eukaryotic cells. They are surrounded by two membranes and have cristae, which are folds in the inner membrane that increase surface area. Each mitochondrion has its own DNA and ribosomes. Its shape and size vary throughout the cell cycle, during development, and in response to stress conditions.
In addition to their role in ATP production, mitochondria are also responsible for many other vital processes in the cell. For example, they play a key role in programmed cell death (apoptosis), which is an important part of homeostasis. Apoptosis involves apoptotic signals that cause the mitochondria to become leaky and to release cytochrome C, which activates caspases. These proteins are then able to break apart chromosomes and fragment the cell. The resulting fragments are then eliminated by macrophages.
Scientists believe that mitochondria originated when a nucleated cell incorporated an aerobic prokaryote. This resulted in a win-win situation for both cells, as the nucleated cell gained an efficient energy producer and the prokaryote gained protection from the nucleated cell. The prokaryote also provided an alternative method of energy generation by oxidizing fatty acids and glucose, which produced adenosine triphosphate. This is now the dominant energy source in eukaryotic organisms.
They are eukaryotic
The mitochondria are double-membrane-bound organelles found in all aerobic organisms. They are often described as the powerhouse of the cell. They are responsible for the production of ATP, an energy-rich molecule that provides fuel for all cellular processes. They are also known for breaking down the sugar produced during photosynthesis into simpler molecules, or for synthesizing fatty acids and amino acids, which are the building blocks of proteins. In order to make this happen, oxidative phosphorylation takes place in the inner membrane of the mitochondria. It is this process that produces most of the ATP in plants and animals.
The outer mitochondrial membrane is freely permeable to ions and small, uncharged molecules. It contains special channels that transport these ions and molecules across the membrane. The inner membrane is tighter, allowing only large molecules to cross. These molecules include oxidative phosphorylation products and substrates for the tricarboxylic acid cycle (also called the Krebs cycle). The cytoplasm of the mitochondria is filled with a gel-like substance, which is composed of the deoxyribonucleic acid and enzymes of the tricarboxylic acid cycle.
Mitochondria are often seen as round or oblong when isolated or viewed in electron micrograph thin sections. But, in a living cell, they are a dynamic network of interconnected structures that are constantly breaking off and re-fusing with each other. They are also moving throughout the cytoplasm of the plant in response to internal and external stimuli.
It is believed that both mitochondria and chloroplasts began as free-living bacteria that were engulfed by primitive, ancient cells. This process is known as endosymbiosis. The ancestry of mitochondria and chloroplasts has been traced back to the alphaproteobacteria, suggesting that they are descendants of the same ancient bacterial ancestor.
They have an outer membrane
Mitochondria (plural: mitochondria) are essential organelles in the cell, often referred to as the “powerhouses” or “energy factories”. They produce a steady supply of adenosine triphosphate (ATP), the energy currency of the cell. They also regulate cellular metabolism. ATP is produced through a set of complex chemical reactions that are collectively known as oxidative phosphorylation. These reactions require a significant amount of energy, which comes from sugars, which are metabolized inside the mitochondria through aerobic respiration.
In order to generate ATP, the inner membrane of the mitochondria contains a series of protein complexes that transfer electrons from one of its molecules to another. These electrons are then used to activate phosphate bonds to create new ATP molecules. The process of transferring electrons is known as oxidative phosphorylation.
The outer membrane of the mitochondria consists of a thin, hydrophobic layer that is permeable to ions and small uncharged molecules. It is surrounded by the inner membrane, which has many folds called cristae. These folds increase the surface area of the inner membrane, allowing more protein complexes to interact with the cytoplasm. The inner membrane is a tight diffusion barrier to ions and larger molecules, which are only able to cross it with the help of specific transport proteins.
Like other organelles, mitochondria are semi-autonomous and dynamic, changing in shape, number, and position depending on the tissue or developmental stage of the cell. They are also responsive to external stimuli, including exercise, aging, and apoptosis. In addition, they can synthesize a number of coenzymes, such as lipoic acid, pyridoxine, and thiamine. However, humans must obtain some of these coenzymes in the diet as vitamins.
They have an inner membrane
The inner mitochondrial membrane contains a set of complex proteins that form a chain called the electron transport chain, which is responsible for mass energy production. The electrons pass along the chain until they produce ATP, which is used as energy in cellular respiration. The membrane is a tight diffusion barrier to ions and small molecules, which can pass through it with the help of pore-forming protein channels. These include the voltage-dependent anion channel (VDAC) and the permeability transition pore protein PTP.
The outer and inner mitochondrial membranes separate a fluid space, the mitochondrial matrix, from the rest of the cell. The matrix is the site of many enzymatic reactions, including DNA replication, transcription and protein biosynthesis. It also has a high pH of 7.9 to 8, which is necessary for the formation of the trans-membrane electrochemical gradient that drives ATP synthesis.
All eukaryotic cells have mitochondria, and the organelle has a unique function that provides a substantial amount of energy for the entire cell. They convert energy from nutrient sources into ATP, a high-energy compound. It also has other important functions, such as regulation of cellular metabolism and protection from oxidative stress.
A peculiar feature of mitochondria is their shape. These structures are surrounded by two membranes, which create an unusual structure for an intercellular organelle. This shape was originally attributed to the fact that both membranes have a net negative surface charge at neutral pH, due to the lipids and proteins they contain. This causes them to repulse each other, but when cations are added to the medium, the repulsion diminishes and the mitochondria aggregate.
The membranes also have a unique cristae-organizing system, an assembly of one soluble and five membrane proteins. The cristae invaginate the inner membrane and define the third compartment of the mitochondria, the crista lumen. Their morphology is highly variable, and they can be lamellar, fenestrated, or abundant tubulovesicular invaginations.
They have an intermembrane space
Often called the “powerhouses” of cells, mitochondria produce energy through a complex series of chemical reactions. These reactions require a lot of energy, so plants and animals have many mitochondria to produce enough energy for the entire organism. Mitochondria are surrounded by two membranes and have a gel-like matrix inside that contains deoxyribonucleic acid (DNA) and enzymes of the tricarboxylic acid cycle.
When a cell needs more energy, the mitochondria will increase in number by dividing or fusing with other mitochondria. In the latter case, the fusion forms an elongated structure that is more efficient than individual mitochondria. Mitochondria also generate a limited amount of energy without oxygen, by breaking sugars produced during photosynthesis. These molecules then cross the inner membrane with the help of special proteins and are converted to ATP by dephosphorylation, which releases energy. ATP molecules pass back through the inner membrane to the cytosol, and the energy they carry is used by the cell to make RNA and proteins.
It is possible to view the internal structures of mitochondria with electron micrographs, or EMs. The EMs show an outer mitochondrial membrane (OMM) separated from an inner mitochondrial membrane (IMM) by a relatively dilute layer of H+ ions in the intermembrane space, or cristae space (Figure 1A). The OMM has pits that are the site of high-affinity complexes for NAD+, GDA, and NDH, as well as a low-affinity NAD+ dehydrogenase and malate dehydrogenase.
The IMM has a wrinkled surface with lots of folds, which increase its surface area for ATP production. The folds are known as cristae, and they help to increase the surface area for the ATP-producing enzymes. These structures are most visible in tissues with a high energy demand, such as skeletal muscle or heart tissue.