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MITOCHONDRIA

MITOCHONDRIA. Dr. ROOPA. The mitochondrion (plural mitochondria ) is a membrane -bound organelle found in most eukaryotic cells (the cells that make up plants , animals , fungi , and many other forms of life).

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MITOCHONDRIA

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  1. MITOCHONDRIA Dr. ROOPA

  2. The mitochondrion (plural mitochondria) is a membrane-bound organelle found in most eukaryoticcells (the cells that make up plants, animals, fungi, and many other forms of life).

  3. Mitochondria range from 0.5 to 1.0 micrometer (μm) in diameter. These structures are sometimes described as "cellular power plants" because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy.

  4. In addition to supplying cellular energy, mitochondria are involved in other tasks such as signaling, cellular differentiation, cell death, as well as the control of the cell cycle and cell growth. • Mitochondria have been implicated in several human diseases, including mitochondrial disorders[5] and cardiac dysfunction, and may play a role in the aging process.

  5. The organelle is composed of compartments that carry out specialized functions. These compartments or regions include the outer membrane, the intermembrane space, the inner membrane, and the cristae and matrix.

  6. In humans, 615 distinct types of proteins have been identified from cardiac mitochondria.

  7. Structure • A mitochondrion contains outer and inner membranes composed of phospholipid bilayers and proteins. The two membranes, however, have different properties. • there are five distinct compartments within the mitochondrion. 

  8.  outer mitochondrial membrane, the intermembrane space (the space between the outer and inner membranes) the inner mitochondrial membrane the cristae space (formed by infoldings of the inner membrane) the matrix (space within the inner membrane).

  9. Outer membrane • encloses the entire organelle • It contains large numbers of integral proteins called porins. These porins form channels that allow molecules 5000 Daltons or less in molecular weight to freely diffuse from one side of the membrane to the other.

  10. Larger proteins can enter the mitochondrion if a signaling sequence at their N-terminus binds to a large multisubunit protein called translocase of the outer membrane.

  11. Disruption of the outer membrane permits proteins in the intermembrane space to leak into the cytosol, leading to certain cell death.] The mitochondrial outer membrane can associate with the endoplasmic reticulum (ER) membrane, in a structure called MAM (mitochondria-associated ER-membrane). This is important in the ER-mitochondria calcium signaling and involved in the transfer of lipids between the ER and mitochondria.

  12. Intermembrane space • the concentrations of small molecules such as ions and sugars in the intermembrane space is the same as the cytosol. • the protein composition of this space is different from the protein composition of the cytosol. • One protein that is localized to the intermembrane space  cytochrome c.

  13. The inner mitochondrial membrane contains proteins with five types of functions: • Those that perform the redox reactions of oxidative phosphorylation • ATP synthase, which generates ATP in the matrix • Specific transport proteins that regulate metabolite passage into and out of the matrix • Protein import machinery. • Mitochondria fusion and fission protein.

  14. Inner membrane • It contains more than 151different polypeptides •  the inner membrane is rich in an unusual phospholipid, cardiolipin •  the inner membrane doesn't contain porins and is highly impermeable to all molecules

  15. The inner membrane contains proteins with three types of functions; those that carry out the oxidation reactions of the respiratory chain ATP synthase, which makes ATP in the matrix specific transport proteins that regulate the passage of metabolites into and out of the matrix.

  16. Cristae • It expand the surface area of the inner mitochondrial membrane, enhancing its ability to produce ATP. • For typical liver mitochondria the area of the inner membrane is about five times greater than the outer membrane.

  17. Matrix • The matrix is the space enclosed by the inner membrane. It contains about 2/3 of the total protein in a mitochondrion. • important in the production of ATP with the aid of the ATP synthase contained in the inner membrane.  • contains a highly-concentrated mixture of hundreds of enzymes, special mitochondrial ribosomes, tRNA, and several copies of the mitochondrial DNA genome.

  18. FUNCTION OF MITOCHONDRIA • Mitochondria are the site of most of the energy production in eukaryotic cells .

  19. The most prominent roles of mitochondria are to produce ATP (i.e., phosphorylation of ADP) through respiration, and to regulate cellular metabolism. The central set of reactions involved in ATP production are collectively known as the citric acid cycle, or the Krebs Cycle.

  20. This is done by oxidizing the major products of glucose, pyruvate, and NADH, which are produced in the cytosol. This process of cellular respiration, also known as aerobic respiration, is dependent on the presence of oxygen. When oxygen is limited, the glycolytic products will be metabolized by anaerobic fermentation, a process that is independent of the mitochondria. The production of ATP from glucose has an approximately 13-times higher yield during aerobic respiration compared to fermentation.

  21. Energy production in the mitochondria has been called the "power house of the cell". • Mitochondria are very abundant in cells that require lots of energy. • Ex:- Muscle

  22. Other function of mitchondria • Heat production • Storage of calcium ions • Apoptosis-programmed cell death • Cellular proliferation regulation • Regulation of cellular metabolism • Certain heme synthesis reactions • Steroid synthesis.

  23. Unique • Mitochondria are very unique in several regards • have their own circular DNA • have their own Ribosomes. (The DNA in the cell nucleus does not code for the construction of mitochondria. )

  24. All the mitochondria in your body came from your mother. Mitochondria are not part of the genetic code in the nucleus of your cells.

  25. Fathers only give genes to their children. Mothers give genes and cytoplasm to their children in their egg cells. Since mitochondria are in the cytoplasm and reproduce themselves they only are inherited from mothers

  26. Geneticists have used this curious feature of mitochondria to study maternal family lines and rates of evolution.

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