Information about Organelles
In cell biology, an organelle is a specialized subunit within a cell, having a specific function, and separately enclosed within its own lipid membrane.
The name organelle comes from the idea that these structures are to cells what an organ is to the body (hence the name organelle, the suffix -elle being a diminutive). Organelles are identified through the use of microscopy, and can also be identified by cell fractionation.
There are many types of organelles, particularly in the eukaryotic cells of higher organisms. Prokaryotes were once thought not to have organelles, but some examples have now been identified.[1]
Other cell biologists choose to limit the term organelle to include only those which are DNA-containing, having originated from formerly autonomous microscopic organisms acquired via endosymbiosis. The most notable of these organelles having originated from endosymbiont bacteria:
Not all parts of the cell qualify as organelles, and the use of the term to refer to some structures is disputed. These structures are large assemblies of macromolecules that carry out particular and specialized functions, but they lack membrane boundaries. Such cell structures, which are not formally organelles, include:
Not all eukaryotic cells have every one of the organelles listed below. Exceptional species of cells do not have some organelles which might otherwise be considered universal to eukaryotes (such as mitochondria[2]). There are also occasional exceptions to the number of membranes surrounding organelles, listed in the tables below (e.g. some which are listed as double-membraned are sometimes found with single or triple membranes). In addition to this, the amount of the individual organelles varies depending upon the function of the specific cell to which it is found.
Mitochondria and chloroplasts, which have double-membranes and their own DNA, are believed to have originated from incompletely consumed or invading prokaryotic organisms, which were adopted as a part of the invaded cell. This idea is supported in the Endosymbiotic theory.
Originally, the word organelle referred to large lipid-encased formerly autonomous endosymbiont within cells. As other intracellular compartments were discovered, the meaning was generalized to include any lipid-encased intracellular component with a specialized biochemical function.
Other related structures:
..... Click the link for more information.
The name organelle comes from the idea that these structures are to cells what an organ is to the body (hence the name organelle, the suffix -elle being a diminutive). Organelles are identified through the use of microscopy, and can also be identified by cell fractionation.
There are many types of organelles, particularly in the eukaryotic cells of higher organisms. Prokaryotes were once thought not to have organelles, but some examples have now been identified.[1]
Examples and disputes
Some cell biologists consider the term organelle to be synonymous with "cell compartment".Other cell biologists choose to limit the term organelle to include only those which are DNA-containing, having originated from formerly autonomous microscopic organisms acquired via endosymbiosis. The most notable of these organelles having originated from endosymbiont bacteria:
- mitochondria (in almost all eukaryotes)
- chloroplasts (in plants, algae and protists)
Not all parts of the cell qualify as organelles, and the use of the term to refer to some structures is disputed. These structures are large assemblies of macromolecules that carry out particular and specialized functions, but they lack membrane boundaries. Such cell structures, which are not formally organelles, include:
Eukaryotic organelles
Eukaryotes are the most structurally complex cell type, and by definition are in part organized by smaller interior compartments, that are themselves enclosed by lipid membranes that resemble the outermost cell membrane. The larger organelles, such as the nucleus and vacuoles, are easily visible with the light microscope. They were among the first biological discoveries made after the invention of the microscope.Not all eukaryotic cells have every one of the organelles listed below. Exceptional species of cells do not have some organelles which might otherwise be considered universal to eukaryotes (such as mitochondria[2]). There are also occasional exceptions to the number of membranes surrounding organelles, listed in the tables below (e.g. some which are listed as double-membraned are sometimes found with single or triple membranes). In addition to this, the amount of the individual organelles varies depending upon the function of the specific cell to which it is found.
| Organelle | Main function | Structure | Organisms | Notes |
|---|---|---|---|---|
| chloroplast (plastid) | photosynthesis | double-membrane compartment | plants, protists | has some genes |
| endoplasmic reticulum | translation and folding of new proteins (rough endoplasmic reticulum), expression of lipids (smooth endoplasmic reticulum) | single-membrane compartment | all eukaryotes | rough endoplasmic reticulum is covered with ribosomes, has folds which are flat sacs; smooth endoplasmic reticulum has folds which are tubular |
| Golgi apparatus | sorting and modification of proteins | single-membrane compartment | all eukaryotes | cis face (convex) nearest to rough endoplasmic reticum; trans face (concave) farthest to rough endoplasmic reticulum |
| mitochondrion | energy production | double-membrane compartment | most eukaryotes | has some DNA |
| vacuole | storage, homeostasis | single-membrane compartment | eukaryotes | |
| nucleus | DNA maintenance, RNA transcription | double-membrane compartment | all eukaryotes | has bulk of genome |
Mitochondria and chloroplasts, which have double-membranes and their own DNA, are believed to have originated from incompletely consumed or invading prokaryotic organisms, which were adopted as a part of the invaded cell. This idea is supported in the Endosymbiotic theory.
Originally, the word organelle referred to large lipid-encased formerly autonomous endosymbiont within cells. As other intracellular compartments were discovered, the meaning was generalized to include any lipid-encased intracellular component with a specialized biochemical function.
| Organelle/Macromolecule | Main function | Structure | Organisms |
|---|---|---|---|
| acrosome | helps spermatoza fuse with ovum | single-membrane compartment | many animals |
| autophagosome | vesicle which sequesters cytoplasmic material and organelles for degradation | double-membrane compartment | all eukaryotic cells |
| centriole | anchor for cytoskeleton | Microtubule protein | animals |
| cilium | movement in or of external medium | Microtubule protein | animals, protists, few plants |
| glycosome | carries out glycolysis | single-membrane compartment | Some protozoa, such as Trypanosomes. |
| glyoxysome | conversion of fat into sugars | single-membrane compartment | plants |
| hydrogenosome | energy & hydrogen production | double-membrane compartment | a few unicellular eukaryotes |
| lysosome | breakdown of large molecules (e.g. proteins + polysaccharides) | single-membrane compartment | most eukaryotes |
| melanosome | pigment storage | single-membrane compartment | animals |
| mitosome | not characterized | double-membrane compartment | a few unicellular eukaryotes |
| myofibril | muscular contraction | bundled filaments | animals |
| nucleolus | ribosome production | protein-DNA-RNA | most eukaryotes |
| parenthesome | not characterized | not characterized | fungi |
| peroxisome | breakdown of metabolic hydrogen peroxide | single-membrane compartment | all eukaryotes |
| ribosome | translation of RNA into proteins | RNA-protein | eukaryotes, prokaryotes |
| vesicle | material transport | single-membrane compartment | all eukaryotes |
Other related structures:
Prokaryotic organelles
Prokaryotes are not as structurally, nor metabolically complex as eukaryotes, and were once thought not to have any internal structures enclosed by lipid membranes. In the past they were often viewed as having little internal organization, but slowly details are emerging about prokaryotic internal structures. One contributing discovery was that at least some prokaryotes have microcompartments, which are compartments enclosed by proteins.[1] Even more striking is the description of magnetosomes,[4][5] as well as the nucleus-like structures of the Planctomycetes that are surrounded by lipid membranes.[6]| Organelle/Macromolecule | Main function | Structure | Organisms |
|---|---|---|---|
| carboxysome | carbon fixation | protein-shell compartment | some bacteria |
| chlorosome | photosynthesis | light harvesting complex | green sulfur bacteria |
| flagellum | movement in external medium | protein filament | some prokaryotes and eukaryotes |
| magnetosome | magnetic orientation | inorganic crystal, lipid membrane | magnetotactic bacteria |
| nucleoid | DNA maintenance & transcription to RNA | DNA-protein | prokaryotes |
| plasmid | DNA exchange | circular DNA | some bacteria |
| ribosome | translation of RNA into proteins | RNA-protein | eukaryotes, prokaryotes |
| thylakoid | photosynthesis | photosystem proteins and pigments | mostly cyanobacteria |
See also
References
1. ^ Kerfeld CA, Sawaya MR, Tanaka S, et al (2005). "Protein structures forming the shell of primitive bacterial organelles". Science 309 (5736): 936-8. PMID 16081736.
2. ^ Fahey RC, Newton GL, Arrack B, Overdank-Bogart T, Baley S (1984). "Entamoeba histolytica: a eukaryote without glutathione metabolism". Science 224 (4644): 70-72. PMID 6322306.
3. ^ Kerfeld CA, Sawaya MR, Tanaka S, et al (2005). "Protein structures forming the shell of primitive bacterial organelles". Science 309 (5736): 936-8. PMID 16081736.
4. ^ Komeili A, Li Z, Newman DK, Jensen GJ (2006). "Magnetosomes are cell membrane invaginations organized by the actin-like protein MamK". Science 311 (5758): 242-5. PMID 16373532.
5. ^ Scheffel A, Gruska M, Faivre D, Linaroudis A, Plitzko JM, Schüler D (2006). "An acidic protein aligns magnetosomes along a filamentous structure in magnetotactic bacteria". Nature 440 (7080): 110-4. PMID 16299495.
6. ^ Fuerst JA (2005). "Intracellular compartmentation in planctomycetes". Annu. Rev. Microbiol. 59: 299-328. PMID 15910279.
2. ^ Fahey RC, Newton GL, Arrack B, Overdank-Bogart T, Baley S (1984). "Entamoeba histolytica: a eukaryote without glutathione metabolism". Science 224 (4644): 70-72. PMID 6322306.
3. ^ Kerfeld CA, Sawaya MR, Tanaka S, et al (2005). "Protein structures forming the shell of primitive bacterial organelles". Science 309 (5736): 936-8. PMID 16081736.
4. ^ Komeili A, Li Z, Newman DK, Jensen GJ (2006). "Magnetosomes are cell membrane invaginations organized by the actin-like protein MamK". Science 311 (5758): 242-5. PMID 16373532.
5. ^ Scheffel A, Gruska M, Faivre D, Linaroudis A, Plitzko JM, Schüler D (2006). "An acidic protein aligns magnetosomes along a filamentous structure in magnetotactic bacteria". Nature 440 (7080): 110-4. PMID 16299495.
6. ^ Fuerst JA (2005). "Intracellular compartmentation in planctomycetes". Annu. Rev. Microbiol. 59: 299-328. PMID 15910279.
- Alberts, Bruce et al. (2002). The Molecular Biology of the Cell, 4th ed., Garland Science, 2002, ISBN 0-8153-3218-1.
Organelles of the cell |
|---|
| Acrosome - Cell wall - Cell membrane - Chloroplast - Cilium/Flagellum - Centrosome - Cytoplasm - Endoplasmic reticulum - Endosome - Golgi apparatus - Lysosome - Melanosome - Mitochondrion - Myofibril - Nucleus - Nucleolus - Parenthesome - Peroxisome - Plastid - Ribosome - Vacuole - Vesicle |
| Organism→System→Organ→Tissue→Cell→Organelle→Molecule→Atom→Subatomic particle→Elementary particle |
Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells. This includes their physiological properties, their structure, the organelles they contain, interactions with
..... Click the link for more information.
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing
..... Click the link for more information.
..... Click the link for more information.
organ (Latin: organum, "instrument, tool") is a group of tissues that perform a specific function or group of functions. Usually there is a main tissue and sporadic tissues. The main tissue is the one that is unique for the specific organ.
..... Click the link for more information.
..... Click the link for more information.
body is the integral physical material of an individual. "Body" often is used in connection with appearance, health issues and death. The study of the workings of the body is physiology.
..... Click the link for more information.
..... Click the link for more information.
A diminutive is a formation of a word used to convey a slight degree of the root meaning, smallness of the object or quality named, encapsulation, intimacy, or endearment. It is the opposite of an augmentative.
..... Click the link for more information.
..... Click the link for more information.
Microscopy is any technique for producing visible images of structures or details too small to otherwise be seen by the human eye, using a microscope or other magnification tool. It is often used more specifically as a technique of using a microscope.
..... Click the link for more information.
..... Click the link for more information.
Cell fractionation is the separation of homogeneous sets, usually organelles, from a heterogeneous population of cells.
..... Click the link for more information.
Steps
- Disruption (homogenisation) of cells and liberation of organelles.
- Macro Filtration
- Purification of cell components.
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
Prokaryotes (IPA: /prəʊˈkæriəʊtiz/) are a group of organisms that lack a cell nucleus (= karyon), or any other membrane-bound organelles.
..... Click the link for more information.
..... Click the link for more information.
An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis (Greek: endo = inner, sym = together and biosis = living).
..... Click the link for more information.
..... Click the link for more information.
An endosymbiont is any organism that lives within the body or cells of another organism, i.e. forming an endosymbiosis (Greek: endo = inner, sym = together and biosis = living).
..... Click the link for more information.
..... Click the link for more information.
Bacteria
Phyla
Actinobacteria
Aquificae
Chlamydiae
Bacteroidetes/Chlorobi
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Deinococcus-Thermus
Dictyoglomi
Fibrobacteres/Acidobacteria
Firmicutes
Fusobacteria
..... Click the link for more information.
Phyla
Actinobacteria
Aquificae
Chlamydiae
Bacteroidetes/Chlorobi
Chloroflexi
Chrysiogenetes
Cyanobacteria
Deferribacteres
Deinococcus-Thermus
Dictyoglomi
Fibrobacteres/Acidobacteria
Firmicutes
Fusobacteria
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide to produce sugars, the raw material for energy and biomass production in all green plants
..... Click the link for more information.
..... Click the link for more information.
The evolution of flagella is of great interest to biologists because the three known varieties of flagella (eukaryotic, bacterial, and archaebacterial) each represent an extremely sophisticated cellular structure that requires the interaction of many different and finely-tuned
..... Click the link for more information.
..... Click the link for more information.
macromolecule implies large molecule. In the context of science and engineering, the term may be applied to conventional polymers and biopolymers (such as DNA) as well as non-polymeric molecules with large molecular mass such as lipids or macrocycles.
..... Click the link for more information.
..... Click the link for more information.
A ribosome is a small, dense, functional structure found in most known cells that assemble proteins and polypeptides used in cell division. It catalyses the assembly of individual amino acids into polypeptide chains by reading messenger RNAs and binding amino acids that are
..... Click the link for more information.
..... Click the link for more information.
cytoskeleton is a cellular "scaffolding" or "skeleton" contained, as all other organelles, within the cytoplasm. It is contained in all eukaryotic cells and recent research has shown it can be present in prokaryotic cells too.
..... Click the link for more information.
..... Click the link for more information.
For the insect anatomical structure, see .
A flagellum (plural: flagella) is a long, slender projection from the cell body, composed of microtubules and surrounded by the plasma membrane...... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
nucleus (3) ribosome (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth ER (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13) centrioles]]
In cell biology, the nucleus (pl.
..... Click the link for more information.
In cell biology, the nucleus (pl.
..... Click the link for more information.
vacuole (11) cytoplasm (12) lysosome (13) centrioles]] Vacuoles are found in the cytoplasm of most plant cells. Vacuoles are membrane-bound compartments within some eukaryotic cells that can serve a variety of secretory, excretory, and storage functions.
..... Click the link for more information.
..... Click the link for more information.
optical microscope, often referred to as a "light microscope", is a type of microscope which uses visible light and a system of lenses to magnify images of small samples. Optical microscopes are the oldest and simplest of the microscopes.
..... Click the link for more information.
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. Chloroplasts absorb sunlight and use it in conjunction with water and carbon dioxide to produce sugars, the raw material for energy and biomass production in all green plants
..... Click the link for more information.
..... Click the link for more information.
Plastids are major organelles found in plants and algae.
..... Click the link for more information.
Plastids in plants
Plastids are responsible for photosynthesis, storage of products like starch and for the synthesis of many classes of molecules such as fatty acids and terpenes which are needed as cellular..... Click the link for more information.
Editing of this page by unregistered or newly registered users is currently disabled due to vandalism.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
If you are prevented from editing this page, and you wish to make a change, please discuss changes on the talk page, request unprotection, log in, or .
..... Click the link for more information.
This article is copied from an article on Wikipedia.org - the free encyclopedia created and edited by online user community. The text was not checked or edited by anyone on our staff. Although the vast majority of the wikipedia encyclopedia articles provide accurate and timely information please do not assume the accuracy of any particular article. This article is distributed under the terms of GNU Free Documentation License.
Herod_Archelaus
