Re: what is the working relationship between cell membranes and mitochondria?
Mitochondria or evolved versions of them are found in all eukaryotes. Based on extensive molecular analyses of their genomes, it is clear that. Mitochondria are the working organelles that keep the cell full of energy. Mitochondria The outer membrane covers the organelle and contains it like a skin. Components of a typical mitochondrion. 1 Outer membrane. Porin. 2 Intermembrane space . The endosymbiotic relationship of mitochondria with their host cells was popularized by Lynn Margulis. The endosymbiotic hypothesis suggests.
You can learn more about chloroplasts, chlorophyll, and photosynthesis in the photosynthesis topic section. Mitochondria Mitochondria singular, mitochondrion are often called the powerhouses or energy factories of the cell.
The process of making ATP using chemical energy from fuels such as sugars is called cellular respirationand many of its steps happen inside the mitochondria. The mitochondria are suspended in the jelly-like cytosol of the cell. They are oval-shaped and have two membranes: Electron micrograph of a mitochondrion, showing matrix, cristae, outer membrane, and inner membrane.
Modification of work by Matthew Britton; scale-bar data from Matt Russell. The matrix contains mitochondrial DNA and ribosomes. We'll talk shortly about why mitochondria and chloroplasts have their own DNA and ribosomes.
The multi-compartment structure of the mitochondrion may seem complicated to us. That's true, but it turns out to be very useful for cellular respirationallowing reactions to be kept separate and different concentrations of molecules to be maintained in different "rooms.
Electrons from fuel molecules, such as the sugar glucose, are stripped off in reactions that take place in the cytosol and in the mitochondrial matrix. These electrons are captured by special molecules called electron carriers and deposited into the electron transport chaina series of proteins embedded in the inner mitochondrial membrane. As protons flow back down their gradient and into the matrix, they pass through an enzyme called ATP synthase, which harnesses the flow of protons to generate ATP.
This process of generating ATP using the proton gradient generated by the electron transport chain is called oxidative phosphorylation. The compartmentalization of the mitochondrion into matrix and intermembrane space is essential for oxidative phosphorylation, as it allows a proton gradient to be established. These electrons are captured by special molecules called electron carriers and deposited into the electron transport, a series of proteins embedded in the inner mitochondrial membrane.
For instance, muscle cells typically have high energy needs and large numbers of mitochondria, while red blood cells, which are highly specialized for oxygen transport, have no mitochondria at all. Both mitochondria and chloroplasts contain their own DNA and ribosomes. Strong evidence points to endosymbiosis as the answer to the puzzle.
Symbiosis is a relationship in which organisms from two separate species live in a close, dependent relationship. The first endosymbiotic event occurred: Mitochondria spread by growth and division of previously existing mitochondria.
Mitochondria are thus able to tell building blocks for new mitochondria where to go and what to do. Recent discoveries have revealed that mitochondria actually have a lot of extramitochondrial molecules that help regulate the expression of genes that turn into mitochondrial proteins. Peroxisomal-proliferator-actived receptor coactivator 1 PGC1 plays a major role in this process.
Structure of Mitochondria
Role in Aging[ edit ] Scientists believe that there is a strong correlation between mitochondrial dysfunction. Mitochondrial dysfunction is one of mitochondrial diseases and is caused by reactive oxygen species ROS. Reactive oxygen species cause oxidative damage that degrades the ability of mitochondria to make ATP.
This means that mitochondria fail to carry out their metabolic functions, leading to cell death . Since mitochondrial dysfunction is a factor of cell death, it is reasonable to believe that such a correlation between mitochondrial dysfunction and aging exists.
It should be noted before anything that regulation of complex protein-folding environment within the organelle is vital for keeping productive metabolic output. The reason for its necessity is that without efficient metabolic output, chemical wastes and heat produced in metabolic processes, which are potential harms to the cell, cannot be transported out of the cell.
Despite the fact the cells do have such complex systems to maintain efficient metabolic output, several factors come into play to prevent this.
We note 2 factors here; 1. It is inevitable that over a long period of time, dysregulation of protein homeostatis arises through stress caused by the accumulation of reactive oxygen species. A failure at maintaining efficient metabolic output can also be induced by mutations in the mitochondrial genome introduced during replication.
These two reasons that deteriorate mitochondria's normal functions are dependent on time; the longer a mitochondrion lives, the magnitude of these time-related effects increases. Therefore, it is believed that damage incurred on mitochondria is deeply involved in aging. Reactive Oxygen Species ROS Having explained that reactive oxygen species are a crucial factor in aging, it is necessary to figure out what they really are.
By definition, they are chemically reactive molecules containing oxygen. Sources of ROS in living cells Roles of the mitochondrial proteome in aging The mitochondrial proteome sustains the cell's cellular metabolism.
Cellular metabolism inside itochondria such as ATP production, apoptosis, and regulation of intracellular calcium. They are all essential elements to sustain life. However, the costs of maintaining such functions are the damaging effects of reactive oxygen species, as mentioned earlier.
triplexxx.info: Cell Structure: Mitochondria
The mitochondrial proteome comprises mitochondrial and nuclear DNA-encoded proteins that needs folding and assembly within mitochondria. The two genomes that code for the structural requirements are damaged by accumulation of reactive oxygen species over time.
The proteome of mammals is made up of between to proteins. Here is a summary of protein production. The list shows how proteins made in the cell are transported into mitochondria in the cell. Unfolded proteins are needed to to construct ETC in mitochondria. To assist mitochondrial biogensis and transferring of mtDNA and proteome, mitochondria must go through series of fission and fusion.
Just like other organelles do, this organelle fission functions to multiply the number of mitochondria. It also serves to remove defective organelles for autophagic degradation  Misfolded and misassembled mitochondrial proteins Researchers have found that inhibition of mtDNA replication, accumulation of orphaned mitochondrial complex subunits or harmful protein aggregates and ROS all can create an excessive amount of misfolded mitochondrial proteins in yeast and Caenorhabditis elegans.
It should be reasonable that accumulation of such misfolded and misassembled proteins generated by those factors lead to destruction of certain mitochondrial metabolic function and its dysfunction ultimately. Here is a summary of how aging disease in mitochondria occurs 1. Reactive oxygen species accumulate inside the mitochondrion 2. This follows two possible consequences. It should be emphasized once again that reactive oxygen species are highly reactive agents.
The other possible consequence is reactive oxygen species directly attack mitochondrial proteins. The proteins are distorted as a result.Mitochondria - Structure of a cell - Biology - Khan Academy
What encoded and translated from these mutated mtDNA are, in fact, misfolded proteins. Keep in mind that proteins are used to build the complicated network of ETC. When misfold proteins are created, as long as they are present in the mitochondria, they will be used as building blocks of ETC. ETCs with misfolded proteins embedded in them no longer function properly. In other words, the mitochondria face ETC dysfunction. ETCs with misfolded proteins cause to create more reactive oxygen species.
As more reactive oxygen species are generated, this vicious cycle continues and misfolded proteins accumulate inside the mitochondria. Over time, the mitochondria die. Non-native amino acids that damage the three dimensional structure of proteins are actively generated in the process of cytosolic translation of mitochondrial proteins .
Complex I is known to possess about 45 subunits. And mutations or functional failures are known to be potential causes of neurodegenerative diseases. They are organelles that act like a digestive system which takes in nutrients, breaks them down, and creates energy rich molecules for the cell.
The biochemical processes of the cell are known as cellular respiration. Many of the reactions involved in cellular respiration happen in the mitochondria. Mitochondria are the working organelles that keep the cell full of energy.
Mitochondria are small organelles floating free throughout the cell. Some cells have several thousand mitochondria while others have none. Muscle cells need a lot of energy so they have loads of mitochondria. If a cell feels it is not getting enough energy to survive, more mitochondria can be created.
Sometimes a mitochondria can grow larger or combine with other mitochondria.