click below
click below
Normal Size Small Size show me how
BIOL 114
Ch 3: Molecules of Life
Term | Definition |
---|---|
Amino acid | An organic molecule containing a carboxyl group, an amino group, a hydrogen atom, and a variable side chain; serves as the monomer of proteins. |
Atherosclerosis | A cardiovascular disease in which growths called plaques develop on the inner walls of the arteries, narrowing the passageways through which blood can flow. |
Carbohydrate | A biological molecule consisting of simple single-monomer sugars (monosaccharides), two-monomer sugars (disaccharides), and other multi-unit sugars (polysaccharides). |
Cellulose | A large polysaccharide composed of many glucose monomers linked into cable-like fibrils that provide structural support in plant cell walls. Because cellulose cannot be digested by animals, it acts as roughage, or fiber, in the diet. |
Dehydration reaction | A chemical process in which a polymer forms when monomers are linked by the removal of water molecules. One molecule of water is removed for each pair of monomers linked. A dehydration reaction is the opposite of a hydrolysis reaction. |
Denaturation | A process in which a protein unravels, losing its specific conformation and hence function; can be caused by changes in pH or salt concentration or by high temperature; also refers to the separation of the two strands of the DNA double helix, caused by similar factors. |
Disaccharide | A sugar molecule consisting of two monosaccharides linked by a dehydration reaction. |
DNA | The genetic material that organisms inherit from their parents; a double-stranded helical macromolecule consisting of nucleotide monomers with deoxyribose sugar, a phosphate group, and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T). See also gene. |
Double helix | The form assumed by DNA in living cells, referring to its two adjacent polynucleotide strands wound into a spiral shape. |
fat | A large lipid molecule made from an alcohol called glycerol and three fatty acids; a triglyceride. Most fats function as energy-storage molecules. |
Functional group | The atoms that form the chemically reactive part of an organic molecule. |
Gene | A unit of inheritance in DNA (or RNA, in some viruses) consisting of a specific nucleotide sequence that programs the amino acid sequence of a polypeptide. Most of the genes of a eukaryote are located in its chromosomal DNA; a few are carried by the DNA of mitochondria and chloroplasts. |
Glycogen | A complex, extensively branched polysaccharide made up of many glucose monomers; serves as an energy-storage molecule in liver and muscle cells. |
Hydrocarbon | A chemical compound composed only of the elements carbon and hydrogen. |
Hydrogenation | The process of converting unsaturated fats to saturated fats by the addition of hydrogen. |
Hydrolysis | A chemical process in which macromolecules are broken down by the chemical addition of water molecules to the bonds linking their monomers; an essential part of digestion. A hydrolysis reaction is the opposite of a dehydration reaction. |
Hydrophilic | "Water-loving"; pertaining to polar, or charged, molecules (or parts of molecules), which are soluble in water. |
Hydrophobic | "Water-fearing"; pertaining to nonpolar molecules (or parts of molecules), which do not dissolve in water. |
Isomer | One of two or more molecules with the same molecular formula but different structures and thus different properties. |
Lipids | An organic compound consisting mainly of carbon and hydrogen atoms linked by nonpolar convalent bonds and therefore mostly hydrophobic and insoluble in water. Lipids include fats, waxes, phospholipids, and steroids. |
Macromolecule | A giant molecule in a living organism. Examples include proteins, polysaccharides, and nucleic acids. |
Manomers | A chemical subunit that serves as a building block of a polymer. |
Monosaccharide | The smallest kind of sugar molecule; a single-unit sugar; also known as a simple sugar. Monosaccharides are the building blocks of more complex sugars and polysaccharides. |
Nucleic acid | A polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and, through the actions of proteins, for all cellular structures and activities. The two types of nucleic acids are DNA and RNA. |
Nucleotide | An organic monomer consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group. Nucleotides are the building blocks of nucleic acids. |
Organic compound | A chemical compound containing the element carbon and usually synthesized by cells. |
Peptide bond | The covalent linkage between two amino acid units in a polypeptide, formed by a dehydration reaction between two amino acids. |
Polymer | A large molecule consisting of many identical or similar molecular units, called monomers, covalently joined together in a chain. |
Polyp | One of two types of cnidarian body forms; a sessile, columnar, hydra-like body. |
Polypeptide | A chain of amino acids linked by peptide bonds. |
Polysaccharides | A carbohydrate polymer consisting of many monosaccharides (sugars) linked by covalent bonds. |
Primary structure | The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain. |
Protein | A biological polymer constructed from amino acid monomers. |
RNA | A type of nucleic acid consisting of nucleotide monomers with a ribose sugar, a phosphate group, and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses. |
Saturated | Pertaining to fats and fatty acids whose hydrocarbon chains contain the maximum number of hydrogens and therefore have no double covalent bonds. Saturated fats and fatty acids solidify at room temperature. |
Starch | A storage polysaccharide found in the roots of plants and certain other cells; a polymer of glucose. |
Steroid | A type of lipid whose carbon skeleton is in the form of four fused rings: three 6-sided rings and one 5-sided ring, Examples are cholesterol, testosterone, and estrogen. |
Sugar-phosphate backbone | The alternating chain of sugar and phosphate to which DNA and RNA nitrogenous bases are attached. |
Trans fat | An unsaturated fatty acid produced by the partial hydrogenation of vegetable oils and present in hardened vegetable oils, most margarines, commercial baked foods, and many fried foods. |
Triglyceride | A dietary fat, which consists of a molecule of glycerol linked to three molecules of fatty acid. |
Unsaturated | Pertaining to fats and fatty acids whose hydrocarbon chains lack the maximum number of hydrogen atoms and therefore have one or more double covalent bonds. Unsaturated fats and fatty acids do not solidify at room temperature. |