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63-461: The greens at the Kabul Golf Club are actually brown to black due to their composition of a mixture of sand and oil (which keeps the sand from blowing). Plans for a modern irrigation system are moribund due to lack of funds. Mainly affluent Afghans and foreigners frequent the course. The 2005 entrance fee for The Kabul Golf Club ( http://www.kabulgolfclub.org ) is 750 Afghani ($ 15 US Dollars) and

126-421: A biosynthetic migration of the original C-13 atom. Ingestion of these C-nor-D-homosteroids results in birth defects in lambs: cyclopia from cyclopamine and leg deformity from veratramine. A further C-nor-D-homosteroid (nakiterpiosin) is excreted by Okinawan cyanobacteriosponges . e.g., Terpios hoshinota , leading to coral mortality from black coral disease. Nakiterpiosin-type steroids are active against

189-436: A C-5 to C-6 double bond, differs from testosterone and progesterone which have a C-4 to C-5 double bond. Almost all biologically relevant steroids can be presented as a derivative of a parent cholesterol -like hydrocarbon structure that serves as a skeleton . These parent structures have specific names, such as pregnane , androstane , etc. The derivatives carry various functional groups called suffixes or prefixes after

252-670: A barrel of crude into various products results in an increase to 45 US gallons (37 imp gal; 170 L). In the 18th and 19th centuries, whale oil was commonly used for lamps, which was replaced with natural gas and then electricity. Crude oil can be refined into a wide variety of component hydrocarbons . Petrochemicals are the refined components of crude oil and the chemical products made from them. They are used as detergents , fertilizers , medicines , paints , plastics , synthetic fibers , and synthetic rubber . Organic oils are another important chemical feedstock, especially in green chemistry . Steroid This

315-428: A chiral center based on their atomic number. The highest priority group is assigned to the atom with the highest atomic number, and the lowest priority group is assigned to the atom with the lowest atomic number. The molecule is then oriented so that the lowest priority group points away from the viewer, and the remaining three groups are arranged in order of decreasing priority around the chiral center. If this arrangement

378-449: A double bond between carbons 5 and 6 and the Δ steroids are those with a double bond between carbons 4 and 5. The abbreviations like " P4 " for progesterone and " A4 " for androstenedione for refer to Δ -steroids, while " P5 " for pregnenolone and " A5 " for androstenediol refer to Δ -steroids. The suffix -ol denotes a hydroxy group , while the suffix -one denotes an oxo group. When two or three identical groups are attached to

441-460: A number of bone-degenerative diseases. Steroidogenesis is the biological process by which steroids are generated from cholesterol and changed into other steroids. The pathways of steroidogenesis differ among species. The major classes of steroid hormones, as noted above (with their prominent members and functions), are the progestogens , corticosteroids (corticoids), androgens , and estrogens . Human steroidogenesis of these classes occurs in

504-400: A number of disorders, including malignancies like prostate cancer , where steroid production inside and outside the tumour promotes cancer cell aggressiveness. The hundreds of steroids found in animals, fungi, and plants are made from lanosterol (in animals and fungi; see examples above) or cycloartenol (in other eukaryotes). Both lanosterol and cycloartenol derive from cyclization of

567-540: A number of locations: In plants and bacteria, the non-mevalonate pathway (MEP pathway) uses pyruvate and glyceraldehyde 3-phosphate as substrates to produce IPP and DMAPP. During diseases pathways otherwise not significant in healthy humans can become utilized. For example, in one form of congenital adrenal hyperplasia a deficiency in the 21-hydroxylase enzymatic pathway leads to an excess of 17α-Hydroxyprogesterone (17-OHP) – this pathological excess of 17-OHP in turn may be converted to dihydrotestosterone (DHT,

630-471: A part of a hydroxy group). The numbering of positions of carbon atoms in the steroid nucleus is set in a template found in the Nomenclature of Steroids that is used regardless of whether an atom is present in the steroid in question. Unsaturated carbons (generally, ones that are part of a double bond) in the steroid nucleus are indicated by changing -ane to -ene. This change was traditionally done in

693-438: A potent androgen) through among others 17,20 Lyase (a member of the cytochrome P450 family of enzymes), 5α-Reductase and 3α-Hydroxysteroid dehydrogenase . Steroids are primarily oxidized by cytochrome P450 oxidase enzymes, such as CYP3A4 . These reactions introduce oxygen into the steroid ring, allowing the cholesterol to be broken up by other enzymes into bile acids. These acids can then be eliminated by secretion from

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756-407: A religious medium. It is often considered a spiritually purifying agent and is used for anointing purposes. As a particular example, holy anointing oil has been an important ritual liquid for Judaism and Christianity . Oils have been consumed since ancient times. Oils hold lots of fats and medical properties. A good example is olive oil. Olive oil holds a lot of fats within it which is why it

819-402: A saturation of carbons 4 and 5 of testosterone with two hydrogen atoms is 4,5α-dihydrotestosterone or 4,5β-dihydrotestosterone. Generally, when there is no ambiguity, one number of a hydrogen position from a steroid with a saturated bond may be omitted, leaving only the position of the second hydrogen atom, e.g., 5α-dihydrotestosterone or 5β-dihydrotestosterone . The Δ -steroids are those with

882-464: A true nucleus and membrane-bound organelles. Steroids are integral to eukaryotic cellular membranes, where they help maintain membrane integrity and function. During eukaryogenesis (the emergence of modern eukaryotic cells), steroids likely played a role in the acquisition of mitochondria via endocytosis. In prokaryotes , biosynthetic pathways exist for the tetracyclic steroid framework (e.g. in myxobacteria ) – where its origin from eukaryotes

945-466: A vowel, the trailing "e" is removed from that name. An example of such removal is " 5α-pregnan-17α-ol-3,20-dione ", where the last "e" of " pregnane " is dropped due to the vowel ("o") at the beginning of the suffix -ol. Some authors incorrectly use this rule, eliding the terminal "e" where it should be kept, or vice versa. The term "11-oxygenated" refers to the presence of an oxygen atom as an oxo (=O) or hydroxy (-OH) substituent at carbon 11. "Oxygenated"

1008-464: A year membership is $ 300 (15,000 Afghani). The club is run by Mohammad Afzal Abdul (also called Mohammed Bashir), its director and golf pro , who worked as a caddy at the course as a young man before fleeing into exile in Pakistan . Business has dropped off since opening as international agency staffing has declined. Originally six holes, the course opened in 1967 during the reign of Mohammed Zahir Shah ,

1071-470: Is also important in medicine. The gonane (steroid nucleus) is the parent 17-carbon tetracyclic hydrocarbon molecule with no alkyl sidechains. Secosteroids (Latin seco , "to cut") are a subclass of steroidal compounds resulting, biosynthetically or conceptually, from scission (cleavage) of parent steroid rings (generally one of the four). Major secosteroid subclasses are defined by the steroid carbon atoms where this scission has taken place. For instance,

1134-412: Is also the target of cholesterol-lowering drugs, such as statins . In humans and other animals the biosynthesis of steroids follows the mevalonate pathway, which uses acetyl-CoA as building blocks for dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). In subsequent steps DMAPP and IPP conjugate to form farnesyl diphosphate (FPP), which further conjugates with each other to form

1197-454: Is an accepted version of this page A steroid is an organic compound with four fused rings (designated A, B, C, and D) arranged in a specific molecular configuration . Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity ; and as signaling molecules . Examples include the lipid cholesterol , sex hormones estradiol and testosterone , anabolic steroids , and

1260-483: Is available at the Misplaced Pages MeSH catalog. Examples of this classification include: In biology, it is common to name the above steroid classes by the number of carbon atoms present when referring to hormones: C 18 -steroids for the estranes (mostly estrogens), C 19 -steroids for the androstanes (mostly androgens), and C 21 -steroids for the pregnanes (mostly corticosteroids). The classification " 17-ketosteroid "

1323-399: Is clockwise, it is assigned an R configuration; if it is counterclockwise, it is assigned an S configuration. In contrast, steroid nomenclature uses α and β to denote stereochemistry at chiral centers. The α and β designations are based on the orientation of substituents relative to each other in a specific ring system. In general, α refers to a substituent that is oriented towards the plane of

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1386-430: Is conjectured – and the more-common pentacyclic triterpinoid hopanoid framework. Fungal steroids include the ergosterols , which are involved in maintaining the integrity of the fungal cellular membrane. Various antifungal drugs , such as amphotericin B and azole antifungals , utilize this information to kill pathogenic fungi. Fungi can alter their ergosterol content (e.g. through loss of function mutations in

1449-471: Is consistently used within the chemistry of the steroids since the 1950s. Some studies use the term "11-oxyandrogens" as an abbreviation for 11-oxygenated androgens, to emphasize that they all have an oxygen atom attached to carbon at position 11. However, in chemical nomenclature, the prefix "oxy" is associated with ether functional groups, i.e., a compound with an oxygen atom connected to two alkyl or aryl groups (R-O-R), therefore, using "oxy" within

1512-427: Is cycloartenol. The mevalonate pathway (also called HMG-CoA reductase pathway) begins with acetyl-CoA and ends with dimethylallyl diphosphate (DMAPP) and isopentenyl diphosphate (IPP). DMAPP and IPP donate isoprene units, which are assembled and modified to form terpenes and isoprenoids (a large class of lipids, which include the carotenoids and form the largest class of plant natural products ). Here,

1575-1202: Is no evidence that NASA has used whale oil. Some oils burn in liquid or aerosol form, generating light , and heat which can be used directly or converted into other forms of energy such as electricity or mechanical work. In order to obtain many fuel oils, crude oil is pumped from the ground and is shipped via oil tanker or a pipeline to an oil refinery . There, it is converted from crude oil to diesel fuel (petrodiesel), ethane (and other short-chain alkanes ), fuel oils (heaviest of commercial fuels, used in ships/furnaces), gasoline (petrol), jet fuel , kerosene , benzene (historically), and liquefied petroleum gas . A 42-US-gallon (35 imp gal; 160 L) barrel of crude oil produces approximately 10 US gallons (8.3 imp gal; 38 L) of diesel, 4 US gallons (3.3 imp gal; 15 L) of jet fuel, 19 US gallons (16 imp gal; 72 L) of gasoline, 7 US gallons (5.8 imp gal; 26 L) of other products, 3 US gallons (2.5 imp gal; 11 L) split between heavy fuel oil and liquified petroleum gases, and 2 US gallons (1.7 imp gal; 7.6 L) of heating oil. The total production of

1638-622: Is preferred for lubricating clocks, because it does not evaporate, leaving dust, although its use was banned in the US in 1980. It is a long-running myth that spermaceti from whales has still been used in NASA projects such as the Hubble Space Telescope and the Voyager probe because of its extremely low freezing temperature. Spermaceti is not actually an oil, but a mixture mostly of wax esters, and there

1701-465: Is remote (and was unknown at the time of its discovery), and because it is obtained in the vicinity of rocks, underground traps, and sands. Mineral oil also refers to several specific distillates of crude oil. Several edible vegetable and animal oils, and also fats , are used for various purposes in cooking and food preparation. In particular, many foods are fried in oil much hotter than boiling water. Oils are also used for flavoring and for modifying

1764-401: The anti-inflammatory corticosteroid drug dexamethasone . Hundreds of steroids are found in fungi , plants , and animals . All steroids are manufactured in cells from the sterols lanosterol ( opisthokonts ) or cycloartenol (plants). Lanosterol and cycloartenol are derived from the cyclization of the triterpene squalene . Steroids are named after the steroid cholesterol which

1827-488: The functional groups attached to this four-ring core and by the oxidation state of the rings. Sterols are forms of steroids with a hydroxy group at position three and a skeleton derived from cholestane . Steroids can also be more radically modified, such as by changes to the ring structure, for example, cutting one of the rings. Cutting Ring B produces secosteroids one of which is vitamin D 3 . Gonane , also known as steran or cyclopentanoperhydrophenanthrene,

1890-463: The triterpenoid squalene . Lanosterol and cycloartenol are sometimes called protosterols because they serve as the starting compounds for all other steroids. Steroid biosynthesis is an anabolic pathway which produces steroids from simple precursors. A unique biosynthetic pathway is followed in animals (compared to many other organisms ), making the pathway a common target for antibiotics and other anti-infection drugs. Steroid metabolism in humans

1953-423: The activated isoprene units are joined to make squalene and folded into a set of rings to make lanosterol . Lanosterol can then be converted into other steroids, such as cholesterol and ergosterol . Two classes of drugs target the mevalonate pathway : statins (like rosuvastatin ), which are used to reduce elevated cholesterol levels , and bisphosphonates (like zoledronate ), which are used to treat

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2016-539: The application of the prefix "keto" for steroid names, and favor the prefix "oxo" (e.g., 11-oxo steroids rather than 11-keto steroids), because "keto" includes the carbon that is part of the steroid nucleus and the same carbon atom should not be specified twice. Steroids are found in all domains of life including bacteria , archaea , and eukaryotes . In eukaryotes, steroids are found in fungi, plants, and animals. Eukaryotic cells, which include animals, plants, fungi, and protists, have complex cellular structures with

2079-583: The base structure at different positions, the suffix is indicated as -diol or -triol for hydroxy, and -dione or -trione for oxo groups, respectively. For example, 5α-pregnane-3α,17α-diol-20-one has a hydrogen atom at the 5α position (hence the "5α-" prefix), two hydroxy groups (-OH) at the 3α and 17α positions (hence "3α,17α-diol" suffix) and an oxo group (=O) at the position 20 (hence the "20-one" suffix). However, erroneous use of suffixes can be found, e.g., "5α-pregnan-17α-diol-3,11,20-trione" [ sic ] — since it has just one hydroxy group (at 17α) rather than two, then

2142-403: The enzymes ERG3 or ERG6 , inducing depletion of ergosterol, or mutations that decrease the ergosterol content) to develop resistance to drugs that target ergosterol. Ergosterol is analogous to the cholesterol found in the cellular membranes of animals (including humans), or the phytosterols found in the cellular membranes of plants. All mushrooms contain large quantities of ergosterol, in

2205-896: The excess grime and creating a layer where new grime could form but be easily washed off in the water as oil is hydrophobic. Fish oils hold the omega-3 fatty acid. This fatty acid helps with inflammation and reduces fat in the bloodstream.   Color pigments are easily suspended in oil, making it suitable as a supporting medium for paints . The oldest known extant oil paintings date from 650 AD. Oils are used as coolants in oil cooling , for instance in electric transformers . Heat transfer oils are used both as coolants (see oil cooling ), for heating (e.g. in oil heaters ) and in other applications of heat transfer. Given that they are non-polar, oils do not easily adhere to other substances. This makes them useful as lubricants for various engineering purposes. Mineral oils are more commonly used as machine lubricants than biological oils are. Whale oil

2268-481: The fluidity of cell membranes and is a principal constituent of plaque (implicated in atherosclerosis ). Steroid hormones include: The major classes of steroid hormones , with prominent members and examples of related functions, are: Additional classes of steroids include: As well as the following class of secosteroids (open-ring steroids): Steroids can be classified based on their chemical composition. One example of how MeSH performs this classification

2331-448: The genus Veratrum ), cardiac glycosides , the phytosterols and the brassinosteroids (which include several plant hormones). Animal steroids include compounds of vertebrate and insect origin, the latter including ecdysteroids such as ecdysterone (controlling molting in some species). Vertebrate examples include the steroid hormones and cholesterol; the latter is a structural component of cell membranes that helps determine

2394-892: The goal of restoring the golf course and related facilities. 34°33′01″N 69°02′07″E  /  34.55023°N 69.03517°E  / 34.55023; 69.03517 Oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water ) and lipophilic (mixes with other oils). Oils are usually flammable and surface active . Most oils are unsaturated lipids that are liquid at room temperature. The general definition of oil includes classes of chemical compounds that may be otherwise unrelated in structure, properties, and uses. Oils may be animal , vegetable , or petrochemical in origin, and may be volatile or non-volatile. They are used for food (e.g., olive oil ), fuel (e.g., heating oil ), medical purposes (e.g., mineral oil ), lubrication (e.g. motor oil ), and

2457-484: The latter is accomplished ( biomimetically ) or (more frequently) through ring closures of acyclic precursors with more (or fewer) ring atoms than the parent steroid framework. Combinations of these ring alterations are known in nature. For instance, ewes who graze on corn lily ingest cyclopamine (shown) and veratramine , two of a sub-family of steroids where the C- and D-rings are contracted and expanded respectively via

2520-405: The linear triterpenoid squalene. Squalene biosynthesis is catalyzed by squalene synthase , which belongs to the squalene/phytoene synthase family . Subsequent epoxidation and cyclization of squalene generate lanosterol, which is the starting point for additional modifications into other steroids (steroidogenesis). In other eukaryotes, the cyclization product of epoxidized squalene (oxidosqualene)

2583-542: The manufacture of many types of paints, plastics, and other materials. Specially prepared oils are used in some religious ceremonies and rituals as purifying agents. First attested in English 1176, the word oil comes from Old French oile , from Latin oleum , which in turn comes from the Greek ἔλαιον ( elaion ), "olive oil, oil" and that from ἐλαία ( elaia ), " olive tree", "olive fruit". The earliest attested forms of

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2646-412: The modern economy. Crude oil originates from ancient fossilized organic materials , such as zooplankton and algae , which geochemical processes convert into oil. The name "mineral oil" is a misnomer , in that minerals are not the source of the oil—ancient plants and animals are. Mineral oil is organic. However, it is classified as "mineral oil" instead of as "organic oil" because its organic origin

2709-495: The name of a steroid class may be misleading. One can find clear examples of "oxygenated" to refer to a broad class of organic molecules containing a variety of oxygen containing functional groups in other domains of organic chemistry, and it is appropriate to use this convention. Even though "keto" is a standard prefix in organic chemistry, the 1989 recommendations of the Joint Commission on Biochemical Nomenclature discourage

2772-417: The parent name, adding a prefix to denote the position, with or without Δ (Greek capital delta) which designates unsaturation, for example, 4-pregnene-11β,17α-diol-3,20-dione (also Δ -pregnene-11β,17α-diol-3,20-dione) or 4-androstene-3,11,17-trione (also Δ -androstene-3,11,17-trione). However, the Nomenclature of Steroids recommends the locant of a double bond to be always adjacent to the syllable designating

2835-575: The pathogenic fungal species Pneumocystis jirovecii does not, which has important clinical implications (given the mechanism of action of many antifungal drugs). Using the fungus Saccharomyces cerevisiae as an example, other major steroids include ergosta‐5,7,22,24(28)‐tetraen‐3β‐ol , zymosterol , and lanosterol . S. cerevisiae utilizes 5,6‐dihydroergosterol in place of ergosterol in its cell membrane. Plant steroids include steroidal alkaloids found in Solanaceae and Melanthiaceae (specially

2898-547: The prototypical secosteroid cholecalciferol , vitamin D 3 (shown), is in the 9,10-secosteroid subclass and derives from the cleavage of carbon atoms C-9 and C-10 of the steroid B-ring; 5,6-secosteroids and 13,14-steroids are similar. Norsteroids ( nor- , L. norma ; "normal" in chemistry, indicating carbon removal) and homosteroids (homo-, Greek homos ; "same", indicating carbon addition) are structural subclasses of steroids formed from biosynthetic steps. The former involves enzymic ring expansion-contraction reactions, and

2961-481: The range of tens to hundreds of milligrams per 100 grams of dry weight. Oxygen is necessary for the synthesis of ergosterol in fungi. Ergosterol is responsible for the vitamin D content found in mushrooms; ergosterol is chemically converted into provitamin D2 by exposure to ultraviolet light . Provitamin D2 spontaneously forms vitamin D2. However, not all fungi utilize ergosterol in their cellular membranes; for example,

3024-435: The removal of land mines . In the process of restoration to its present state, three Soviet tanks and a multiple rocket launcher were removed by a nonprofit agency. In 2004 the Kabul Golf Club was reopened again. During the intervening seven years little has changed. Play on the golf course has been sporadic, and at the mercy of the local security situation. Beginning in 2011, a fund-raising effort has been underway with

3087-480: The respective numbers, indicating their position in the steroid nucleus. There are widely used trivial steroid names of natural origin with significant biologic activity, such as progesterone , testosterone or cortisol . Some of these names are defined in The Nomenclature of Steroids. These trivial names can also be used as a base to derive new names, however, by adding prefixes only rather than suffixes, e.g.,

3150-478: The ring scissions (cleavages), expansions and contractions (cleavage and reclosing to a larger or smaller rings)—all variations in the carbon-carbon bond framework—steroids can also vary: For instance, sterols such as cholesterol and lanosterol have a hydroxyl group attached at position C-3, while testosterone and progesterone have a carbonyl (oxo substituent) at C-3. Among these compounds, only lanosterol has two methyl groups at C-4. Cholesterol which has

3213-428: The ring system, while β refers to a substituent that is oriented away from the plane of the ring system. In steroids drawn from the standard perspective used in this paper, α-bonds are depicted on figures as dashed wedges and β-bonds as solid wedges. The name " 11-deoxycortisol " is an example of a derived name that uses cortisol as a parent structure without an oxygen atom (hence "deoxy") attached to position 11 (as

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3276-593: The signaling pathway involving the smoothened and hedgehog proteins, a pathway which is hyperactive in a number of cancers. Steroids and their metabolites often function as signalling molecules (the most notable examples are steroid hormones), and steroids and phospholipids are components of cell membranes . Steroids such as cholesterol decrease membrane fluidity . Similar to lipids , steroids are highly concentrated energy stores. However, they are not typically sources of energy; in mammals, they are normally metabolized and excreted. Steroids play critical roles in

3339-473: The simplest steroid and the nucleus of all steroids and sterols, is composed of seventeen carbon atoms in carbon-carbon bonds forming four fused rings in a three-dimensional shape . The three cyclohexane rings (A, B, and C in the first illustration) form the skeleton of a perhydro derivative of phenanthrene . The D ring has a cyclopentane structure. When the two methyl groups and eight carbon side chains (at C-17, as shown for cholesterol) are present,

3402-491: The steroid 17α-hydroxyprogesterone has a hydroxy group (-OH) at position 17 of the steroid nucleus comparing to progesterone. The letters α and β denote absolute stereochemistry at chiral centers —a specific nomenclature distinct from the R/S convention of organic chemistry to denote absolute configuration of functional groups, known as Cahn–Ingold–Prelog priority rules . The R/S convention assigns priorities to substituents on

3465-504: The steroid is said to have a cholestane framework. The two common 5α and 5β stereoisomeric forms of steroids exist because of differences in the side of the largely planar ring system where the hydrogen (H) atom at carbon-5 is attached, which results in a change in steroid A-ring conformation. Isomerisation at the C-21 side chain produces a parallel series of compounds, referred to as isosteroids. Examples of steroid structures are: In addition to

3528-431: The suffix should be -ol, rather than -diol, so that the correct name to be "5α-pregnan-17α-ol-3,11,20-trione". According to the rule set in the Nomenclature of Steroids, the terminal "e" in the parent structure name should be elided before the vowel (the presence or absence of a number does not affect such elision). This means, for instance, that if the suffix immediately appended to the parent structure name begins with

3591-399: The texture of foods (e.g. stir fry ). Cooking oils are derived either from animal fat, as butter , lard and other types, or plant oils from olive , maize , sunflower and many other species. Oils are applied to hair to give it a lustrous look, to prevent tangles and roughness and to stabilize the hair to promote growth. See hair conditioner . Oil has been used throughout history as

3654-418: The unsaturation, therefore, having it as a suffix rather than a prefix, and without the use of the Δ character, i.e. pregn-4-ene-11β,17α-diol-3,20-dione or androst-4-ene-3,11,17-trione . The double bond is designated by the lower-numbered carbon atom, i.e. "Δ -" or "4-ene" means the double bond between positions 4 and 5. The saturation of carbons of a parent steroid can be done by adding "dihydro-" prefix, i.e.,

3717-533: The way that they are made by an organism, their chemical structure and their limited solubility in water compared to oils. They have a high carbon and hydrogen content and are considerably lacking in oxygen compared to other organic compounds and minerals; they tend to be relatively nonpolar molecules, but may include both polar and nonpolar regions as in the case of phospholipids and steroids. Crude oil, or petroleum , and its refined components, collectively termed petrochemicals , are crucial resources in

3780-775: The word are the Mycenaean Greek 𐀁𐀨𐀺 , e-ra-wo and 𐀁𐁉𐀺 , e-rai-wo , written in the Linear B syllabic script. Organic oils are produced in remarkable diversity by plants, animals, and other organisms through natural metabolic processes. Lipid is the scientific term for the fatty acids , steroids and similar chemicals often found in the oils produced by living things, while oil refers to an overall mixture of chemicals. Organic oils may also contain chemicals other than lipids, including proteins , waxes (class of compounds with oil-like properties that are solid at common temperatures) and alkaloids . Lipids can be classified by

3843-419: Was also used in lighting in ancient Greece and Rome. So people would use it to bulk out food so they would have more energy to burn through the day. Olive oil was also used to clean the body in this time as it would trap the moisture in the skin while pulling the grime to the surface. It was used as an ancient form of unsophisticated soap. It was applied on the skin then scrubbed off with a wooden stick pulling off

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3906-490: Was closed in 1978, and reopened in 2004. During these three decades it has undergone several changes. It was relocated to its present site in 1973 after the king was overthrown in a coup d'état and completely closed following a 1978 communist coup . It was reopened in 1993 but closed again in 1996 when the Taliban regime banned sports. After the 2001 invasion of Afghanistan , the course was used as an area for military training in

3969-431: Was first described in gall stones from Ancient Greek chole- ' bile ' and stereos 'solid'. The steroid nucleus ( core structure ) is called gonane (cyclopentanoperhydrophenanthrene). It is typically composed of seventeen carbon atoms, bonded in four fused rings: three six-member cyclohexane rings (rings A, B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Steroids vary by

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