Definitions:

Carbon is a versatile molecule because an atom of carbon can share electrons with other atoms in four covalent bonds that can branch off in four directions. Because C can use one or more of its bonds to attach to other carbons atoms, it is possible to construct an endless diversity of C skeletons varying in size and branching pattern. Thus, molcules wiht multiple C intersections can form very elaborate shapes. The C atoms of organic compounds can also bond with other elements, mostly hydrogen, oxygen and nitrogen.

Carbohydrates: are a loosely defined group of molecuels that all contain carbon, hydrogen, and oxysten in the molar ratio 1:2:1. The empirical formula (which lists the number of atoms in the molecuels with subscripts) is (CH2O)n, where n is the number of C atoms. Because they contain many Carbon-hydrogen (C-H) bonds, which release energy when they are rearranged, carbohydrates are well suited for energy storage. Sugars are among the most important energy storage molecules and they exist in several different forms. 

The simplest of the carbohydrates are the monosaccharides. Simple sugarrs contain as few as 3 carbon atoms, but those that play the central role in energy storage have 6. The empirical formula of 6 carbon sugars is C6H12O2 or (CH2O)6. The most important 6 carbon sugar used for energy storage is glucose. 

Hydrocarbons: are molecules that consit only of carbon and hydrogen. Because the oxidation of hydrocarbons compounds results in a net reelase of energy, hydrocarbons make good fuels. Gasloine, for example, is rich in hydrocarbons and propane (C3H8) gas, another hydrocarbon, consists of a chain of three C atoms with 8 hydrogen atoms bound to it. C and H atoms both have very similar electronegativities.

Disaccharide: Most organisms transport sugars within their bodies. In humans, the glucose that circualtes in the blood does so as a simple monosacharide. In plants and many other organisms, however, glucose is converted into a transport form before it is moved. In such a form, it is less readily metabolied during transport. Transoport forms are sugars are commonly made by linking tow monosaccharides together to form a disacharide. Disaccharides serve as effective reserovirs of glucose becasue the enzymes that normally use glucose in the organisms cannot break the bond linking the two monosaccharide sbunits. Enzymes that can do so are typically present only in teh tissue that uses glucose. 

Glucose: is the most important 6 carbon sugar used for energy storage. Glucose has 7 enery storing C-H bonds. Depending on the orientation of the carobnly group group when the ring is clsoed, glucose can exist in two different forms: alpha or beta. This is significant when glucose is used as a monomer to form polymers. 

Lactose: When glutose is linked to the steroisomer galactose, the resulting disacharide is lactose, or milk sugar. Many mammals supply energy to theri young in the form of lactose. Adults often ahve greatly reduced levels of lactase, the enzyme required to cleave lactose into its two monosaccharide components, and thus they cannot metaolize lactose efficiently. This can result in lactose intolerance in numans. 

Lipids: have a very high proportion o nonpolar carbon-hydrogen bonds. Long chain lipids cannot fold up like a protein to confine theri nonpolar portions away from the surrounding acqueous enviornment. Intead, may lipid molecuels cluster together and expose what polar (hydrophoilic) groups they have to the surrounding water while confining the nonpolar (hydrophobic) parts together within the cluster. Many lipids are build from fatty acids and glycerol. Many lipd molecuels consist of a glycerol molecule with three fatty acids attached, one to each carbon of the glycerol backbone. Becasue it contains three fatty acids, a fat molecule is commonly called a triglyceride. Organisms contain many other kinds of lipids besdies fats. Terpenes are long chain lipids that are components of many biologically important pigments such a chlorophyll and the visual pigment retinal. Rubber is also a terpene. Steroids, another class of lipid, are composed of four carbon rings. Most animal cell membranes contain the steroid cholesterol. Other steroids such a testosterone and estrogen, function as hormones in multicellular animals. Prostaglandins are a group o about 20 lipids taht are modified fatty acids, with two nonpolar toails attached toa 5 carbon ring. Prostaglandins act as local chemical messengers in many vertebrate tissues. 

Phospholipids: are complex lipid molecules which form the core of all biological membranes. Individual phospholipids can be thought of a a substituted triglyceride with a phosphate replacing one of the fatty acids. Thus the basic strcutre of a phospholipid includes 1) glycerol, 2) fatty ais and a 3) phosphate group.

Fats: consit of fatty acid polymers attached to glycerol. Fats are excellent energy storage molecules. Most fats contain over 40 carbon atoms. The ratio of C-H bonds in fats is more than twice that o carbohydrates. This means that fats are relatively more reduced than carbohydrates, and will thus release more energy upon oxidation. This makes fats much mroe efficient molecuels for storing chemical energy. Most fats produced by anims are saturated (except some fish oils) whereas most plant fats are unsaturated. 

–Fatty acids are long chain hydrocarbons with a carboxyl group (COOH) at one end. If all of the internal carbon atoms in a fatty acid are bonded to two hydrogen atoms, the fatty is is saturated with the maxim number of H atoms possible. A faty acid with double bonds between one or mroe pairs of sussive carbon atoms will have fewer hydrogen atms, and is thus unsaturated. The presence o a double bond in fatty acids makes unsaturated fats liquid at room temperature Ooils) because of the lack of rotation around the double bonds which produces a kink in the chain whereas saturated fats (animal fat and butter) are solid at room temperature. . 

–Glycerol: is a 3 carbon polyalcohol (three -OH groups). 

Sucrose: When glucose forms a disaccharide with teh structural isomer fructose, the resulting disaccharide is sucrose, or table sugar. Sucrose is the form most plants use to transport glucose and is the sugar that most humans and other animals eat. Sugarcane and sugar beets are rich in sucrose. 

Non-polar: Electons in C-C and C-H bond thus are evenly distributed, with no significant differences in charge over the molecular surface. For this reason, hydrocarbons are nonpolar. 

Polar: Because other atoms besides H and C frequently have different electronegativities, molecuels containing them exhibit regions of partial positive or negative charge. They are polar. 

Functional groups: include groups like the hydroxyl group (-OH). Functional groups have definite chemical properties that they retain no matter where they occur. Both the hydroxyl and carbonyl group, for example, are polar because of the electronegativity of the oxygen atoms. Other common functional groups are the acidic carboxyl (COOH), the phosphate (PO4-) and the basic amino (NH2) groups. Many of these funcitonal groups can also participate in hydrogen bonding. 

Types of Hydrocarbons

Hydrocarbons are organic compounds which consist entirely of H and C. Typically, substituted chemical moieties include one or more substituents that replace hydrogen. Examples include halo, alkyl, cycloalkyl, aralkyl, aryl, sulfhydryl, hydroxyl (-OH), alkoxyl, cyano (-CN), carboxyl (-COOH), and the like. See US 2010/0075375 A1 for definitions. 

Alkyl: refers to a saturated straight, branched, or cyclic hydrocarbon having from 1-22 C atoms. Alkyl groups include methyl, ethyl, n-propyl, isopropyl, no-butyl, isobutyl, t-butyl, n-pentyl, cyclopentyl, isopentyl, neopentyl, etc.

Alkane: are carbon chains held together by single bonds. 

–Methane (CH4): is the simplest organic compound.It is abundant in natural gas and is also produced by prokarytoes that live in swamps and in the digestive tracts of grazing animals.

–Octane: are the main molecules in gasoline.

Aryl: refers to an optionally substituted, mono or bicyclic aromatic ring system having from about 5-14 carbon atoms. Examples include phenyl.

Aralkyl: reefers to alkyl radicals bearing an aryl substitutent and have from about 6- 22 C atoms. Aralkyl groups can be optionally substituted. Examples include benzyl, naphthylmethy, diphenylmethyl, triphenylmethyl…

Alkoxy/Alkoxyl: refer to an optionally substiuted alkyl-O- group. Examples include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, etc.

Functional Groups

The unique properties of an organic compound depend not only on its carbon skeleton but also on the atoms attached to the skeleton. These groups which are directly involved in chemical reactions are called “functional groups”. 

–-Hydroxyl group (OH): found in alcohols such as isopropyl rubbing alcohol.

Carboxyl group (-COOH): is found in all proteins.

Aroyl: refers to a -C(=O)-aryl group.

Carboxy: refers to a -C(=O)(OH) group

Polysaccharides: 

Polysaccharides are longer polymers made up of monosacharides that have been joined through dehydration reactions. 

Starch: is a storage polyacharide that consists entirely of alpha-glucose molecules linked in long chains. Thring due to bonds between the C1 of one molecule and the C-6 of anohter (alpha (1-6) linkage). 

Amylose: is a starch with the simplest structure is amylose which is composed of many hundreds of alpha-glucose molecules linked together in long, unbranched chains. Each linkage occurs between the carbon 1 of one glucose molecule and the C-4 of another, making them alpha (1-4) linkages. Most plant starch, including the remaining 80% of potato starch, is a somewhat more complicated variant of amylose called amylopectin. Pectins are branched polysaccharides with the brances occcurring due to bonds between the C1 of one molecule and the C6 of another. These short amylose branches consist of 20-30 glucose subunits.

Glucogen: is an insoluble polysaccharide containing branched amylose chains. Glycogen has a much longer average chain lenght and mroe branches than plant starch. 

Cellulose: is a polymer of beta-glucose. The properties of a chain of glucose molecules consisting of all beta-glucose (as apposed to alpha-glucose) are very different form those of starch. These long, unbranched beta-linked cahins make tough fibers. Cellulose is the main component of plant cell walls. It is chemically similar to amylose but enzyems that ocur in most organisms cannot break the bond formed between two beta-glucose units becasue they only recognize alpha linkages. Becasue cellulose cannot be broken down readily by most animals, it works well as a biological structural materail. But some animals such as cows are able to utilize cellulose aided by a symbiotic bacteria and protiests in their digestive tracts. These organisms provide the necessary enzyme to celave the beta (1-4) linkages, releasing glucose for further metabolism. 

Chitin: is a polymer of N-acetylglucosamine, a nitrogen-containg derivative of glucose. When cross-linked by proteins, it forms a tough, resistant surface material that serves as the hard exoskeleton of insects and crutaceans. It is also the structural material found in arthropodes (e.g., lobsters) and many fungi.