Definitions for "Chemistry: Organic Molecules of Life"


Amphipathic: Pertains to a molecule containing both polar (water-soluble) and nonpolar (water-soluble) portions in its structure.

Amino acid: The basic building block of protein. All amino acids contain an amino (NH 2 ) end, a carboxyl end (COOH) and a side group (R).

Amino Group: A functional group with one nitrogen and two hydrogen atoms. You will find them on all of the amino acids.

Carbohydrate: Defined as polyhydroxyaldehydes, or polyhydroxyketones, and their derivatives. They act as the primary biological means of storing or consuming energy. Simple carbohydrates consist of monosaccharides such as glucose and fructose and di-saccharides such as sucrose and lactose. They are quick sources of energy. Complex Carbohydrates consist of polysaccharides and take a longer time for the body to break them down into glucose; examples are starches, cellulose, glycogen and chitin.

Carbon: The 12th element in the periodic table, mass 12.000. Carbon is one of the most versatile elements and combines with itself and many other elements to form a huge variety of organic compounds, for example, hydrocarbons and their derivatives, some of which are found in the atmosphere.

Carboxyl Group: A -COOH functional group. One of the oxygens is double-bonded to the carbon atom, making it a carbonyl group, and the other oxygen is single bonded to the carbon on one side, and single bonded to the hydrogen on the other. The remaining bond on the carbon atom is attached to the rest of the molecule.

Cellulose: A complex carbohydrate that is the chief component of the cell walls of plants, composed of a long chain of repeating glucose units. Cellulose can only be digested by bacteria, which often grow symbiotically in the guts of animals like ruminants and termites.

Chitin: A complex carbohydrate forming the outer shell of arthropods, insects, crustaceans, fungi and some algae.

Cholesterol: A steroid lipid, found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. Most cholesterol is not dietary in origin, it is synthesized internally.

Covalent bond: The sharing of one or more pairs of electrons between atoms, in order to produce a mutual attraction, which holds the resultant molecule together. Atoms tend to share electrons in such a way that their outer electron shells are filled. Such bonds are always stronger than the intermolecular hydrogen bond and similar in strength to or stronger than the ionic bond.

Denaturation: A process in which a protein unravels and loses its native conformation (secondary, tertiary, and quaternary structure), thereby becoming biologically inactive. For DNA, the separation of the two strands of the double helix. Denaturation occurs under extreme conditions of pH, salt concentration, or temperature.

DNA: A double-stranded nucleic acid that contains the genetic information for cell growth, division, and function.

Domain (of a protein): A defined region of a protein with a distinct structure and function; determined by the 3-dimensional shape of the region.

Double Helix: A pair of parallel helices intertwined about a common axis. This is the conformation or shape that two linear strands of DNA assume when bonded together.

Estradiol: A sex hormone, (17-beta estradiol). Labelled the "female" hormone but also present in males it represents the major estrogen in humans. Critical for sexual functioning estradiol also supports bone growth.

Fructose: A monosaccharide, (C 6 H 12 O 6), found in many foods and one of the three most important blood sugars along with glucose and galactose.

Functional Groups: An atom or group of atoms in an organic compound that gives the compound some of its characteristic properties, such as the C=O functional group in aldehydes and ketones.

Glucose: A simple monosaccharide sugar, (C 6 H 12 O 6 ), is one of the most important carbohydrates and is used as a source of energy in animals and plants. Glucose is one of the main products of photosynthesis and starts respiration.

Glycerol: A three-carbon, syrupy alcohol that forms the backbone of fatty acids in fats.

Glycogen: The principal storage form of glucose in animal cells. In humans and other vertebrates, most glycogen is found in the skeletal muscles, but it is found in the highest concentration in the liver.

Glycoprotein: A molecule that consists of a carbohydrate (sugar) plus a protein. Glycoproteins play essential roles in the body, such as in the immune system where almost all of the key molecules involved in the immune response are glycoproteins.

Lipid: A fatty or waxy organic compound that is readily soluble in nonpolar solvent (e.g. ether) but not in polar solvent (e.g water). Its major biological functions involve energy storage, structural component of cell membrane, and cell signaling. Examples of lipids are waxes, oils, sterols, cholesterol, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides (fats), and phospholipids.

Lipoprotein: A biochemical assembly that contains both proteins and lipids and may be structural or catalytic in function. Lipoproteins may be enzymes, proton pumps, ion pumps, or some combination of these functions. Examples include the high density and low density lipoproteins of the blood and the transmembrane proteins of the mitochondrion and the chloroplast.

Monomer: A monomer is a starting material or single unit from which a polymer is built. It refers to the repeat units that make up the polymer chains. Ethylene is the monomer for polyethylene and styrene for polystyrene.

Monosaccharide: Sugars consisting of a single sugar molecule which cannot be further decomposed by hydrolysis. They form the basis of more complex sugars.

Nucleotide: One of the structural components, or building blocks, of DNA and RNA. A nucleotide consists of a base (one of four chemicals: adenine, thymine, guanine, and cytosine) plus a molecule of sugar and one of phosphoric acid.

Phospholipids: Main lipid component of cell membranes. Phospholipids are a heterogeneous type of molecule composed of glycerol, phosphate, two fatty acid residues, and 'headgroups' with different chemical properties.

Phosphate Group: A functional group on a larger molecule, where the phosphorus is single bonded to each of the four oxygens, and the other bond of one of the oxygens is attached to the rest of the molecule. Many phosphate groups are found in nucleic acids.

Polymer: A generic term used to describe a substantially long molecule. This long molecule consists of structural units and repeating units strung together through chemical bonds. The process of converting these units to a polymer is called polymerization.

Polypeptide: A molecule made up of a string of amino acids. A protein is an example of a polypeptide.

Polysaccharide: Any of a class of carbohydrates whose molecules contain chains of monosaccharide molecules. Examples include cellulose, starch, or glycogen.

Protein: The fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism. Proteins are molecules composed of one or more chains of amino acids in a specific order. This order is determined by the base sequence of nucleotides in the gene coding for the protein.

RNA: A a single-stranded nucleic acid similar to that of DNA, though the deoxyribose acid is replaced with ribose sugar and all thymine bases are replaced with uracil. RNA is a vital component of protein synthesis as it is able to read the genetic blueprint found in DNA to make.

Saturated fat: A fat or fatty acid in which there are no double bonds between the carbon atoms of the fatty acid chain (hence, it is fully saturated with hydrogen atoms). Saturated fats tend to be solid at room temperature. Diets high in saturated fat correlate in some studies with an increased incidence of atherosclerosis and coronary heart disease.

Starch: A complex carbohydrate found chiefly in seeds, fruits, tubers, roots and stem pith of plants, notably in corn, potatoes, wheat, and rice.

Steroids: Member of a large family of structurally similar lipid substances. Steroid molecules have a basic skeleton consisting of four interconnected carbon rings. Different classes of steroids have different functions. All the natural sex hormones are steroids. Anabolic steroids increase muscle mass. Anti-inflammatory steroids (or corticosteroids) can reduce swelling, pain, and other manifestations of inflammation.

Sucrose: A disaccharide, (C 12 H 22 O 11) , consisting of glucose and fructose monomers.

Sugar: The common name for any sweet, crystalline, simple carbohydrate which is an aldehyde or ketone derivative of a polyhydric alcohol. Sugars are mainly disaccharides like sucrose and monosaccharides like fructose, all are soluble indilute alcohol or water and are white in their pure form.

Sulfhydryl Group: Also known as a Thiol. The functional group composed of a sulfur atom and a hydrogen atom (-SH).

Testosterone: A male hormone, considered to be the most potent naturally occurring androgen. Testosterone is made primarily by the testes in men, and it encourages the development of male sex characteristics.

Trans fat: A type of processed fat that does not occur in nature (also called hydrogenated or partially hydrogenated fat/oil). Used in baked goods like doughnuts, potato chips, cookies and many other processed food products. It is an unsaturated fatty acid whose molecules contain trans double bonds between carbon atoms, which makes the molecules less kinked compared to those of 'cis fat'. Research suggests a correlation between diets high in trans fats and diseases like atherosclerosis and coronary heart disease.

Triglyceride: Glyceride occurring naturally in animal and vegetable tissues; it consists of three individual fatty acids bound together in a single large molecule; an important energy source forming much of the fat stored by the body.

Unsaturated fat: A fat or fatty acid in which there is one or more double bonds between carbon atoms of the fatty acid chain. Such fat molecules are monounsaturated if each contains one double bond, and polyunsaturated if each contain more than one. In living organisms, such bonds, which are sometimes referred to as unsaturated bonds, may be either cis or trans.