Mitochondria - Turning on the PowerhouseMitochondria are known as the powerhouses of the cell. 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. Show
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. Neurons (cells that transmit nerve impulses) don’t need as many. 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. It all depends on the needs of the cell.  The folding of the inner membrane increases the surface area inside the organelle. Since many of the chemical reactions happen on the inner membrane, the increased surface area creates more space for reactions to occur. If you have more space to work, you can get more work done. Similar surface area strategies are used by microvilli in your intestines. What’s in the matrix? It's not like the movies at all. Mitochondria are special because they have their own ribosomes and DNA floating in the matrix. There are also structures called granules which may control concentrations of ions. Cell biologists are still exploring the activity of granules. Using Oxygen to Release EnergyHow does cellular respiration occur in mitochondria? The matrix is filled with water and proteins (enzymes). Those proteins take organic molecules, such as pyruvate and acetyl CoA, and chemically digest them. Proteins embedded in the inner membrane and enzymes involved in the citric acid cycle ultimately release water (H2O) and carbon dioxide (CO2) molecules from the breakdown of oxygen (O2) and glucose (C6H12O6). The mitochondria are the only places in the cell where oxygen is reduced and eventually broken down into water. Mitochondria are also involved in controlling the concentration of calcium (Ca2+) ions within the cell. They work very closely with the endoplasmic reticulum to limit the amount of calcium in the cytosol. Related Video...
Chalk Talk: Mitochondria (US-NSF Video) Encyclopedia.com:
The inner mitochondrial membrane (IMM) is the mitochondrial membrane which separates the mitochondrial matrix from the intermembrane space. Structure[edit]The structure of the inner mitochondrial membrane is extensively folded and compartmentalized. The numerous invaginations of the membrane are called cristae, separated by crista junctions from the inner boundary membrane juxtaposed to the outer membrane. Cristae significantly increase the total membrane surface area compared to a smooth inner membrane and thereby the available working space for oxidative phosphorylation. The inner membrane creates two compartments. The region between the inner and outer membrane, called the intermembrane space, is largely continuous with the cytosol, while the more sequestered space inside the inner membrane is called the matrix. Cristae[edit]For typical liver mitochondria, the area of the inner membrane is about 5 times as large as the outer membrane due to cristae. This ratio is variable and mitochondria from cells that have a greater demand for ATP, such as muscle cells, contain even more cristae. Cristae membranes are studded on the matrix side with small round protein complexes known as F1 particles, the site of proton-gradient driven ATP synthesis. Cristae affect overall chemiosmotic function of mitochondria.[1] Cristae junctions[edit]Cristae and the inner boundary membranes are separated by junctions. The end of cristae are partially closed by transmembrane protein complexes that bind head to head and link opposing crista membranes in a bottleneck-like fashion.[2] For example, deletion of the junction protein MIC60/Mic60 (formerly Mitofilin/Fcj1) leads to a reduced inner membrane potential and impaired growth[3] and to dramatically aberrant inner membrane structures which form concentric stacks instead of the typical invaginations.[4] Composition[edit]The inner membrane of mitochondria is similar in lipid composition to the membrane of bacteria. This phenomenon can be explained by the endosymbiont hypothesis of the origin of mitochondria as prokaryotes internalized by a eukaryotic host cell. In pig heart mitochondria, phosphatidylethanolamine makes up the majority of the inner mitochondrial membrane at 37.0% of the phospholipid composition. Phosphatidylcholine makes up about 26.5%, cardiolipin 25.4%, and phosphatidylinositol 4.5%.[5] In S. cerevisiae mitochondria, phosphatidylcholine makes up 38.4% of the IMM, phosphatidylethanolamine makes up 24.0%, phosphatidylinositol 16.2%, cardiolipin 16.1%, phosphatidylserine 3.8%, and phosphatidic acid 1.5%.[6] In the inner mitochondrial membrane, the protein-to-lipid ratio is 80:20, in contrast to the outer membrane, which is 50:50.[7] Permeability[edit]The inner membrane is freely permeable to oxygen, carbon dioxide, and water only.[8] It is much less permeable to ions and small molecules than the outer membrane, creating compartments by separating the matrix from the cytosolic environment. This compartmentalization is a necessary feature for metabolism. The inner mitochondrial membrane is both an electrical insulator and chemical barrier. Sophisticated ion transporters exist to allow specific molecules to cross this barrier. There are several antiport systems embedded in the inner membrane, allowing exchange of anions between the cytosol and the mitochondrial matrix.[7] IMM-associated proteins[edit]
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What is the purpose of the folded inner membrane in mitochondria quizlet?The inner membrane is highly folded providing a large surface area for aerobic respiration.
What is the function of inner membrane?The inner or cytoplasmic membrane, impermeable to polar molecules, regulates the passage of nutrients, metabolites, macromolecules, and information in and out of the cytoplasm and maintains the proton motive force required for energy storage.
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The inner membrane of mitochondria consists of many folds. what is the purpose of this membrane?
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