| Term | Definition |
|---|
| biomolecule | an organic compound normally present as an essential component of living organisms |
| plasma membrane | the exterior membrane surrounding the cytoplasm of a cell |
| cytoplasm | the portion of a cell's contents outside the nucleus but within the plams membrane; includes organelles such as mitochondria |
| cytosol | the continuous aqueous phase of the cytoplasm, with its disolved solutes; excludes the organelles such as mitochondria |
| metabolite | a chemical intermediate in the enzyme-catalyzed reactions of metabolism |
| coenzyme | an organic cofactor required for the action of certain enzymes; often contains a vitamin as a component |
| ribosome | a supramolecular comple of rRNAs and proteins, approximately 18 to 22 nm in diameter; the site of protein synthesis |
| nucleus | in eukaryotes, a membrane-bounded organelle that contains chromosomes |
| nucleoid | in bacteria, the nuclear zone that contains the chromosome but has no surrounding membrane |
| genome | all the genetic information encoded in a cell or virus |
| eukaryote | a unicellular or multicellular organism with cells having a membrane-bounded nucleus, multiple chromosomes, and internal organelles |
| prokaryote | a bacterium; a unicellular organism with a single chromosome, no nuclear envelope, and no membrane-bounded organelles |
| archaebacteria | one of the five kingdoms of living organisms; includes many species that thrive in extreme environments of hight ionic strength, high temperature, and low pH |
| eubacteria | one of the five kingdoms of living organisms; they have a plasma membrane but no internal organelles or nucleus |
| lithotroph | obtain energy from inorganic molecules |
| organotrophs | obtain energy from organic molecules |
| plasmids | an extrachromosomal, independently replicating, small circular DNA molecule; commonly employed in generic engineering |
| cytoskeleton | the filamentous network providing structure and organiation to the cytoplasm; includes actin filaments, microtubules, and intermediate filaments |
| exycytosis | the fusion of an intercellular vesicle with the plasma membrane, releasing the vesicle contents to the extracellular space |
| endocytosis | the uptake of extracellular material by its inclusion within a vesicle (endosome) formed by an invagination of the plasma membrane |
| protein | macromolecule composed of one or more polypeptide chains, each with a characteristic sequence of amino acids linked by peptide bonds |
| nucleic acid | biologically occuring polynucleotides in which the nucleotide residues are linkjed in a specific sequence by phosphodiester bonds; DNA and RNA |
| polysaccharide | a linear or pranched polymer of monosaccharide units linked by glyscosidic bonds |
| lipid | a small, water-insoluble biomolecule generally containing fatty acids, sterols, or isoprenopid compounds |
| chiral center | an atom with substituents arranged so that the molecule is not superimposable on its mirror image |
| enantiomer | stereoisomers that are nonsuperimposable mirror images of each other |
| racemic mixture | an equimolar mixture of the D and L stereoisomers of an optically active compound |
| conformation | the spatial arrangement of substituent groups that are free to assume different positions in space due to the freedom of bond rotation |
| hydrophilic | "water loving" polar or charged molecules that associate (dissolve) easily in water |
| hydrophobic | "water fearing" nonpolar molecules that are insoluble in water |
| amphipathic | containing both polar and nonpolar domains |
| micelle | an aggregate of amphipathic molecules in water, with the nonpolar portions in the interior and the polar portions at the exterior surface, exposed to water |
| hydrophobic interaction | association of nonpolar groups in water to seek their most stable (disordered) state |
| colligative property | properties of solutions that depend on the number of solute particles per unit volume; ie freezing point depression |
| equilibrium constant | Keq; a constant, characteristic for each chemical reaction; relates the specific concentrations of all reactants and products at equilibrium at a given temperature and pressure |
| pH | -log[H+] |
| pKa | -log[Ka] |
| titration curve | the plot of pH versus the equivalents of base added during a titration |
| buffer | a system capable of resisting changes in pH, consisting of a conjugagte acid-base pair in which the ratio of proton acceptor to donor is near unity |
| henderson-hasselbalch equation | an equation relating the pH, the pKa, and the ratio of the concentrations of the proton acceptor (A-) and the proton donor (HA) species in a solution |
| hydrolysis | cleavage of a bond, sucha as an anhydride or peptide bond, by the addition of the elements of water, yielding two or more products |
| hydrolases | enzymes (proteases, lipases, phosphates, nucleases, for example) that catalyze hydrolysis reactions |
| conjugate acid-base pair | a proton donor and its corresponding deprotonated species; for example, acetic acid (donor) and acetate (acceptor) |
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