Mitochondrion: Difference between revisions
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===Inner membrane=== | ===Inner membrane=== | ||
The inner membrane constitutes the framework for electron-transport processes that produce most of the cell's ATP.<ref name=AlbertsMBioCellMitoandChloro/> | |||
In prokaryotes, the plasma membrane is used to produce ATP. However, eukaryotic cells reserve this function for membranes in energy converting organells, mitochondria and plastids<ref>notably chloroplasts—occuring only in plants</ref> and the plasma membrane is reserved for other transport processes. Mitochondria and plastids are morphologically notable for their extensive inner membranes. <ref name=AlbertsMBioCellMitoandChloro/> | |||
==Life cycle== | ==Life cycle== | ||
Revision as of 18:21, 13 January 2008
Template:TOC-right Mitochondria (singular mitochondrion) are the source of energy production within a cell. They are semiautonomous and self producing, residing in the cytoplasm of eukaryotic cells. Converting cellular energy metabolites in the Kreb’s Cycle, through the process of oxidative phosphorylation they produce adenosine triphosphate (ATP) which is used to power other processes in the cell.[1][2][3][4]
Mitochondria are rod shaped[5] organelles [6] with an inner and an outer membrane. The outer membrane limits the organelle. The inner membrane folds in on itself forming the cristae mitochondriales, giving the appearance of partitions and chambers within the organelle in cross section.[7] The cristae number and shape vary according to the type of tissue and organism. Cristae serve to increase the surface area of the inner membrane.[2].
Mitochondria contain their own genome which is separate and distinct from the genome of the cell.[2] Theoretically, mitochondria may have been separate unicellular organisms at one time and were subsumed in a symbiotic relationship into eukaryotic cells at some point in the evolutionary process.[8]
Substructure
The two membranes are separated by space. The space enclosed within the inner memberane is the matrix, a moderately dense region with strands of DNA, ribosomes, or small granules. Using these tools, the mitochondria code for a portion of their own proteins. [3]
Inner membrane
The inner membrane constitutes the framework for electron-transport processes that produce most of the cell's ATP.[8]
In prokaryotes, the plasma membrane is used to produce ATP. However, eukaryotic cells reserve this function for membranes in energy converting organells, mitochondria and plastids[9] and the plasma membrane is reserved for other transport processes. Mitochondria and plastids are morphologically notable for their extensive inner membranes. [8]
Life cycle
Replication
In a process similar to replication in bacterial cells, when a mitochondrion reaches a certain size, they undergo fission, the furrowing of the inner and outermembrane which pinches them into two daughter mitochondria. Prior to fission they replicate their DNA.[10]
Death
Mitochondrion at the end of their life are disposed of through autophagy. Cellular endoplasmic reticulum are wrapped around the mitochondrion forming a vacuole. Golgi complex vesicles containing hydrolases then join with the autophagic vacuole which then degrades the contents of the vacuole, the mitochondrion.[10]
Notes
- ↑ [1] Munich Information Center for Protein Synthesis
- ↑ 2.0 2.1 2.2 What is a cell? National Center for Biotechnology Information, National Library of Medicine, National Insitutes of Health
- ↑ 3.0 3.1 Mitochondrial substructure Cell Biology Graduate Program, University of Texas Medical Branch
- ↑ ATP and oxidative phosphorylation reactions Jakubowski, Henry (2006) College of Saint Benedict, Saint John’s University
- ↑ Usually rod shaped. they may also be round.
- ↑ a word derived from Greek meaning Little organ
- ↑ Mitochondria: Architecture dictates function Cell Biology Graduate Program, University of Texas Medical Branch
- ↑ 8.0 8.1 8.2 Energy Conversion: Mitochondria and Chloroplasts Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., Walter, P. (2002) Molecular Biology of the Cell. NY:Taylor & Francis Group, Garland Science
- ↑ notably chloroplasts—occuring only in plants
- ↑ 10.0 10.1 The mitochondrial life cycle Cell Biology Graduate Program, University of Texas Medical Branch