双语教学中的生物化学词汇

双语生物化学词汇

Glossary of Biochemistry Bilingually

A

Absolute configuration（绝对构型）The configuration of four different substituent groups around an asymmetric carbon atom, in relation to u- and i.-glyceraldehyde. Absorption（吸收）: transport of the products of digestion from the intestinal tract into the blood.

Acceptor control（受体控制）:The regulation of the rate of respiration by the availability of ADP as phosphate group acceptor.

Accessory pigments（辅助色素）:Visible light-absorbing pigments (carotenoids, xanthophyll, and phycobilins藻胆素) in plants and photosynthetic bacteria that complement chlorophylls in trapping energy from sunlight.

Acidosis（酸中毒）: A metabolic condition in which the capacity of the body to buffer is diminished; usually accompanied by decreased blood pH.

Actin（肌动蛋白）: A protein making up the thin filaments（细丝）of muscle; also an important component of the cytoskeleton of many eukaryotic cells.

Activation energy(ΔG*)（活化能）: The amount of energy (in joules) required to convert all the molecules in 1 mole of a reacting substance from the ground state to the transition state.

Activator:（活化物、激活剂）(1) A DNA-binding protein that positively regulates the expression of one or more genes; that is, transcription rates increase when an activator is bound to the DNA. (2) A positive modulator of an allosteric enzyme.

Active site:（活性部位）The region of an enzyme surface that binds the substrate molecule and catalytically transforms it; also known as the catalytic site.

Active transport:（主动运输）Energy-requiring transport of a solute across a membrane in the direction of increasing concentration.

Activity:（活度）The true thermodynamic activity or potential of a substance, as distinct from its molar concentration.

Activity coefficient:（活度系数）The factor by which the numerical value of the concentration of a solute must be multiplied to give its true thermodynamic activity. Adenosine 3',5'-cyclic monophosphate: See cyclic AMP.

Adenosine diphosphate: See ADP.

Adenosine triphosphate: See ATP.

Adipocyte:（脂肪细胞）An animal cell specialized for the storage of fats (triacylglycerols).

Adipose tissue:（脂肪组织）Connective tissue specialized for the storage of large amounts of triacylglycerols.

ADP (adenosine diphosphate):A ribonucleoside diphosphate serving as phosphate group acceptor in the cell energy cycle.

Aerobe:（需氧生物）An organism that lives in air and uses oxygen as the terminal electron acceptor in respiration.

Aerobic: Requiring or occurring in the presence of oxygen.

Alcohol fermentation:（乙醇发酵）The anaerobic conversion of glucose to ethanol via glycolysis. See also fermentation.

Aldose:（醛糖）A simple sugar in which the carbonyl carbon atom is an aldehyde; that is, the carbonyl carbon is at one end of the carbon chain.

Alkalosis:（碱中毒）A metabolic condition in which the capacity of the body to buffer is diminished; usually accompanied by an increase in blood pH.

Allosteric enzyme:（变/别构效应） A regulatory enzyme, with catalytic activity modulated by the noncovalent binding of a specific metabolite at a site other than the active site.

Allosteric protein: （变/别构蛋白）A protein (generally with multiple subunits) with multiple ligand-binding sites, such that ligand binding at one site affects ligand binding at another.

Allosteric site: （变/别构部位）The specific site on the surface of an allosteric enzyme molecule to which the modulator or effector molecule is bound.

α helix:（α-螺旋）A helical conformation of a polypeptide chain, usually right-handed, with maximal intrachain hydrogen bonding; one of the most common secondary structures in proteins.

Ames test:A simple bacterial test for carcinogens, based on the assumption that carcinogens are mutagens.

Amino acid activation:（氨基酸活化）ATP-dependent enzymatic esterification of the carboxyl group of an amino acid to the 3'-hydroxyl group of its corresponding tRNA. Amino acids:（氨基酸）an Amino-substituted carboxylic acids, the building blocks of proteins.

Amino-terminal residue:（氨基末端残基）The only amino acid residue in a polypeptide chain with a free a-amino group; defines the amino terminus of the polypeptide.

Aminoacyl-tRNA:（氨酰tRNA）An aminoacyl ester of a tRNA.

Aminoacyl-tRNA synthetases:（氨酰tRNA合成酶）Enzymes that catalyze synthesis of an aminoacyl-tRNA at the expense of ATP energy.

Aminotransferases:（氨基转移酶）Enzymes that catalyze the transfer of amino groups fromα-amino to α-keto acids; also called transaminases.

Ammonotelic:（排氨的）Excreting excess nitrogen in the form of ammonia. Amphibolic pathway:（双向代谢途径）A metabolic pathway used in both catabolism and anabolism.

Amphipathic:（双亲的）Containing both polar and nonpolar domains. Ampholyte:（两性电解质）A substance that can act as either a base or an acid. Amphoteric:（两性的）Capable of donating and accepting protons, thus able to serve as an acid or a base.

Anabolisim:（合成代谢）The phase of intermediary metabolism concerned with the energy-requiring biosynthesis of cell components from smaller precursors. Anaerobe:（厌氧生物）An organism that lives without oxygen. Obligate anaerobes （专性厌氧生物）die when exposed to oxygen.

Anaerobic:（厌氧的）Occurring in the absence of air or oxygen.

Anaplerotic reaction:（回补反应）An enzyme-catalyzed reaction that can replenish the supply of intermediates in the citric acid cycle.

A ngstrom (?):（唉）A unit of length (10-8cm) used to indicate molecular dimensions. Anhydride:（酸酐）The product, of the condensation of two carboxyl or phosphate groups in which the elements of water are eliminated to form a compound with the general structure R—X—0—X—R, where X is either carbon or phosphorus.

Anion-exchange resin:（阴离子交换树脂）A polymeric resin with fixed cationic groups; used in the chromatographic separation of anions.

Anomers:（异头物、端基异构体）Two stereoisomers of a given sugar that differ only in the configuration about the carbonyl (anomeric) carbon atom.

Antibiotic:（抗生素）One of many different organic compounds that are formed and secreted by various species of microorganisms and plants, are toxic to other species, and presumably have a defensive function.

Antibody:（抗体）A defense protein synthesized by the immune system of vertebrates. See also immunoglobulin.

Anticodon:（反密码子） A specific sequence of three nucleotides in a tRNA, complementary to a codon for an amino acid in an mRNA.

Antigen:（抗原）A molecule capable of eliciting the synthesis of a specific antibody in vertebrates.

Antiparallel:（反平行）Describing two linear polymers that are opposite in polarity or orientation.

Antiport:（反向转运）Cotransport of two solutes across a membrane in opposite directions.

Apoenzyme:（酶蛋白）The protein portion of an enzyme, exclusive of any organic or inorganic cofactors or prosthetic groups that might be required for catalytic activity. Apolipoprotein:（脱辅基脂蛋白）The protein component of a lipoprotein. Apoprotein: （脱辅基蛋白）The protein portion of a protein, exclusive of any organic or inorganic cofactors or prosthetic groups that might be required for activity. Apoptosis:（细胞凋亡）(app'-a-toe'-sis) Programmed cell death, in which a cell brings

about its own death and lysis, signaled from outside or programmed in its genes, by systematically degrading its own macromolecules.

Arrestin:（抑制蛋白） A family of proteins that bind to the phosphorylated carboxyl-terminal region of serpentine receptors, preventing their interactions with G proteins and thereby terminating the signal through those receptors.

Asymmetric carbon atom:（不对称碳原子）A carbon atom that is covalently bonded to four different groups and thus may exist in two different tetrahedral configurations. ATP (adenosine triphosphate): A ribonucleoside 5'-triphosphate functioning as a phosphate group donor in the cell energy cycle; carries chemical energy between metabolic pathways by serving as a shared intermediate coupling endergonic and exergonic reactions.

ATP synthase:（ATP合酶）An enzyme complex that forms ATP from ADP and phosphate during oxidative phosphorylation in the inner mitochondrial membrane or the bacterial plasma membrane, and during photophosphorylation in chloroplasts. ATPase:（ATP酶）An enzyme that hydrolyzes ATP to yield ADP and phosphate; usually coupled to some process requiring energy.

Attenuator:（弱化子）An RNA sequence involved in regulating the expression of certain genes; functions as a transcription terminator.

Autotroph:（自养生物）An organism that can synthesize its own complex molecules from very simple carbon and nitrogen sources, such as carbon dioxide and ammonia. Auxin:（植物生长素）A plant growth hormone.

Auxotrophic mutant (auxotroph):（营养缺陷突变体）A mutant organism defective in the synthesis of a given biomolecule, which must therefore be supplied for the organism's growth.

Avogadro's number: The number of molecules in a gram molecular weight (a mole) of any compound (6.02 × 1023).

B

Back-mutation:（回复突变）A mutation that causes a mutant gene to regain its wild-type base sequence.

Bacteriophage (phage):（噬菌体）A virus capable of replicating in a bacterial cell. Basal metabolic rate:（基础代谢率）The rate of oxygen consumption by an animal's body at complete rest, long after a meal.

Base pair:（碱基对）Two nucleotides in nucleic acid chains that are paired by hydrogen bonding of their bases; for example, A with T or U, and G with C.

β conformation:（β构象）、An extended, zigzag arrangement of a polypeptide chain; a common secondary structure in proteins.

βoxidation:（β氧化）Oxidative degradation of fatty acids into acetyl-CoA by successive oxidations at the β-carbon atom.

β-turn:（β转角）A type of secondary structure in polypeptides consisting of four amino

acid residues arranged in a tight turn so that the polypeptide turns back on itself. Bilayer:（双分子层）A double layer of oriented amphipathic lipid molecules, forming the basic structure of biological membranes. The hydrocarbon tails face inward to form a continuous nonpolar phase.

Bile salts:（胆酸盐）Amphipathic steroid derivatives with detergent properties, participating in digestion and absorption of lipids.

Binding energy:（吸附能）The energy derived from noncovalent interactions between enzyme and substrate or receptor and ligand.

Binding site:（结合部位）The crevice or pocket on a protein in which a ligand binds. Biocytin:（生物胞素）The conjugate amino acid residue arising from covalent attachment of biotin, through an amide linkage, to a Lys residue.

Biomolecule:（生物分子）An organic compound normally present as an essential component of living organisms.

Biopterin:（生物喋呤）An enzymatic cofactor derived from pterin and involved in certain oxidation-reduction reactions.

Biosphere:（生物圈）All the living matter on or in the earth, the seas, and the atmosphere.

Biotin:（生物素）A vitamin; an enzymatic cofactor involved in carboxylation reactions. Bond energy:（键能）The energy required to break a bond.

Branch migration:（分支迁移）Movement of the branch point in branched DNA formed from two DNA molecules with identical sequences. See also Holliday intermediate.

Buffer:（缓冲液）A system capable of resisting changes in pH, consisting of a conjugate acid-base pair in which the ratio of proton acceptor to proton donor is near unity.

C

Calorie:（卡）The amount of heat required to raise the temperature of 1.0 g of water from 14.5 to 15.5 °C. One calorie (cal) equals 4.18 joules (J).

Calvin cycle:（Calvin循环）The cyclic pathway used by plants to fix carbon dioxide and produce triose phosphates.

cAMP:See cyclic AMP.

cAMP receptor protein (CRP): （cAMP受体蛋白）A specific regulatory protein that controls initiation of transcription of the genes producing the enzymes required for a bacterial cell to use some other nutrient when glucose is lacking. Also called catabolite gene activator protein (CAP)，降解物基因活化蛋白.

CAP:See catabolite gene activator protein.

Capsid:（衣壳）The protein coat of a virion or virus particle.

Carbanion:（碳负离子）A negatively charged carbon atom.

Carbocation: （碳正离子）A positively charged carbon atom; also called a carbonium

ion.

Carbon-assimilation reactions:（碳同化反应）Reaction sequences in which atmospheric CO2 is converted into organic compounds.

Carbon-fixation reaction:（固碳反应）The reaction catalyzed by rubisco during photosynthesis, or by other carboxylases, in which atmospheric CO2is initially incorporated into an organic compound.

Carboxyl-terminal residue:（羧基末端残基）The only amino acid residue in a polypeptide chain with a free a-carboxyl group; defines the carboxyl terminus of the polypeptide.

Carotenoids:（类葫罗卜素）Lipid-soluble photosynthetic pigments made up of isoprene units.

Catabolism:（分解代谢）The phase of intermediary metabolism concerned with the energy-yielding degradation of nutrient molecules.

Catabolite gene activator protein (CAP):See cAMP receptor protein.

Catalytic site:（催化部位）See active site.

Catecholamines:（儿茶酚胺类）Hormones, such as epinephrine, that are amino derivatives of catechol.

Catenane:（连环体）Circular polymeric molecules with a noncovalent topological link resembling the links of a chain.

Cation-exchange resin:（阳离子交换树脂）An insoluble polymer with fixed negative charges; used in the chromatographic separation of cationic substances.

cDNA: See complementary DNA.

Central dogma:（中心法则）The organizing principle of molecular biology: genetic information flows from DNA to RNA to protein.

Centromere:（着丝粒） A specialized site within a chromosome, serving as the attachment point for the mitotic or meiotic spindle.

Cerebroside(脑苷酯) Sphingolipid containing one sugar residue as a head group. Channeling:（生物合成途径限制作用)The direct transfer of a reaction product (common intermediate) from the active site of one enzyme to the active site of a different enzyme catalyzing the next step in a sequential pathway.

Chemiosmotic coupling:（化学渗透偶联）Coupling of ATP synthesis to electron transfer via an electrochemical H+ gradient across a membrane.

Chemotaxis（向化性）:A cell's sensing of and movement toward, or away from, a specific chemical agent.

Chemotroph:（化能生物）An organism that obtains energy by metabolizing organic compounds derived from other organisms.

Chiral center:（手性中心）An atom with substituents arranged so that the molecule is not superimposable on its mirror image.

Chiral compound:（手性化合物）A compound that contains an asymmetric center

(chiral atom or chiral center) and thus can occur in two nonsuperimposable mirror-image forms (enantiomers).

Chlorophylls:（叶绿素）A family of green pigments functioning as receptors of light energy in photosynthesis; magnesium-porphyrin complexes.

Chloroplasts:（叶绿体）Chlorophyll-containing photosynthetic organelles in some eukaryotic cells.

Chromatin:（染色质）A filamentous complex of DNA, histones, and other proteins, constituting the eukaryotic chromosome.

Chromatography:（层析）A process in which complex mixtures of molecules are separated by many repeated partitionings between a flowing (mobile) phase and a stationary phase.

Chromosome:（染色体）A single large DNA molecule and its associated proteins, containing many genes; stores and transmits genetic information.

Chylomicron:（乳糜微粒）A plasma lipoprotein consisting of a large droplet of triacylglycerols stabilized by a coat of protein and phospholipid; carries lipids from the intestine to the tissues.

cis and trans isomers:（顺反异构体）See geometric isomers.

Cistron:（顺反子）A unit of DNA or RNA corresponding to one gene.

Citric acid cycle:（柠檬酸循环）A cyclic system of enzymatic. reactions for the oxidation of acetyl residues to carbon dioxide, in which formation of citrate is the first step; also known as the Krebs cycle or tricarboxylic acid cycle.

Clones:（克隆）The descendants of a single cell.

Cloning:The production of large numbers of identical DNA molecules, cells, or organisms, from a single ancestral DNA molecule, cell, or organism.

Closed system:（封闭系统）A system that exchanges neither matter nor energy with the surroundings. See also system.

Cobalamin:（钴胺素）See cocnzyme B12.

Codon:（密码子）A sequence of three adjacent nucleotides in a nucleic acid that codes for a specific amino acid.

Coenzyme:（辅酶）An organic cofactor required for the action of certain enzymes; often contains a vitamin as a component.

Coenzyme A: （辅酶A）A pantothenic acid-containing coenzyme serving as an acyl group carrier in certain enzymatic reactions.

Coenzyme B12: An enzymatic cofactor derived from the vitamin cobalamin, involved in certain types of carbon skeletal rearrangements.

Cofactor(辅助因子) An inorganic ion or a coenzyme required for enzyme activity. Cognate:（相关的）Describing two biomolecules that normally interact; for example, an enzyme and its normal substrate, or a receptor and its normal ligand.

Cohesive ends:（粘性末端）See sticky ends.

Cointegrate:（共整合）An intermediate in the migration of certain DNA transposons in which the donor DNA and target DNA are covalently attached.

Colligative properties:（依数性）Properties of solutions that depend on the number of solute particles per unit volume; for example, freezing-point depression.

Common intermediate:（共同中间产物）A chemical compound common to two chemical reactions, as a product of one and a reactant in the other.

Competitive inhibition:（竞争性抑制作用）A type of enzyme inhibition reversed by increasing the substrate concentration; a competitive inhibitor generally competes with the normal substrate or ligand for a protein's binding site.

Complementary:（互补）Having a molecular surface with chemical groups arranged to interact specifically with chemical groups on another molecule.

Complementary DNA (cDNA): A DNA used in DNA cloning, usually made by reverse transcriptase; complementary to a given mRNA.

Configuration:（构型）The spatial arrangement of an organic molecule that is conferred by the presence of either (1) double bonds, about which there is no freedom of rotation, or (2) chiral centers, around which substituent groups are arranged in a specific sequence. Configurational isomers cannot be interconverted without breaking one or more covalent bonds.

Conformation:（构象）The spatial arrangement, of substituent groups that are free to assume different positions in space, without breaking any bonds, because of the freedom of bond rotation.

Conjugate acid-base pair:（共扼酸碱对） A proton donor and its corresponding deprotonated species; for example, acetic acid (donor) and acetate (acceptor). Conjugate redox pair: （共扼氧还对）An electron donor and its corresponding electron acceptor form; for example, Cu+ (donor) and Cu2+ (acceptor), or NADH (donor) and NAD+ (acceptor).

Conjugated protein:（结合蛋白质）A protein containing one or more prosthetic groups.

Consensus sequence:（一致序列）A DNA or amino acid sequence consisting of the residues that occur most commonly at each position within a set of similar sequences. Conservative substitution:（保守性置换）Replacement of an amino acid residue in a polypeptide by another residue with similar properties; for example, substitution of Glu by Asp.

Constitutive enzymes:（组成酶）Enzymes required at all times by a cell and present at some constant level; for example, many enzymes of the central metabolic pathways. Sometimes called house-keeping enzymes.

Contour length (外形长度): The length of a helical polymeric molecule as measured along the molecule's helical axis.

Corticosteroids（皮质类固醇激素）Steroid hormones formed by the adrenal cortex. Cotransport:（共转运）The simultaneous transport, by a single transporter, of two

solutes across a membrane. See antiport, symport.

Coupled reactions:（偶联反应）Two chemical reactions that have a common intermediate and thus a means of energy transfer from one to the other.

Covalent bond:（共价键）A chemical bond that involves sharing of electron pairs. Cristae:（嵴）Infoldings of the inner mitochondrial membrane.

CRP（cAMP受体蛋白）See cAMP receptor protein.

Cyclic AMP (cAMP):A second messenger within cells; its formation by adenylyl cyclase is stimulated by certain hormones or other molecular signals.

Cyclic electron flow:（循环电子流）In chloroplasts, the light-induced flow of electrons originating from and returning to photosystem I.

Cyclic photophosphorylation: （循环光合磷酸化）ATP synthesis driven by cyclic electron flow through photosystem I.

Cyclin:（细胞周期蛋白）One of a family of proteins that activate cyclin-dependent protein kinases and thereby regulate the cell cycle.

Cytochromes:（细胞色素）Heme proteins serving as electron carriers in respiration, photosynthesis, and other oxidation-reduction reactions.

Cytokine:（细胞因子）One of a family of small secreted proteins (such as interleukins or interferons) that activate cell division or differentiation by binding to plasma membrane receptors in sensitive cells.

Cytokinesis:（胞质分裂）The final separation of daughter cells following mitosis. Cytoplasm:（细胞质）The portion of a cell's contents outside the nucleus but within the plasma membrane; includes organelles such as mitochondria.

Cytoskeleton:（细胞骨架）The filamentous network providing structure and organization to the cytoplasm; includes actin filaments, microtubules, and intermediate filaments.

Cytosol:（细胞浆）The continuous aqueous phase of the cytoplasm, with its dissolved solutes; excludes the organelles such as mitochondria.

D

Dalton:（道尔顿）The weight of a single hydrogen atom (1.66 x I0-24 g).

Dark reactions:（暗反应）See carbon-assimilation reactions.

De novo pathway:（从头合成）Pathway for synthesis of a biomolecule, such as a nucleotide, from simple precursors; as distinct from a salvage pathway. Deamination:（脱氨基作用）The enzymatic removal of amino groups from biomolecules such as amino acids or nucleotides.

Degenerate code:（兼并密码）A code in which a single element in one language is specified by more than one element in a second language.

Dehydrogenases:（脱氢酶类）Enzymes catalyzing the removal of pairs of hydrogen atoms from their substrates.

Deletion mutation:（删除突变）A mutation resulting from the deletion of one or more

nucleotides from a gene or chromosome.

Denaturation:（变性）Partial or complete unfolding of the specific native conformation of a polypeptide chain, protein, or nucleic acid.

Denatured protein:（变性蛋白）A protein that has lost its native conformation by exposure to a destabilizing agent such as heat or detergent.

Deoxyribonucleic acid; See DNA.

Deoxyribonucleotides:（脱氧核糖核苷酸）Nucleotides containing 2-deoxyribose as the pentose component.

Desaturases:（去饱和酶）Enzymes that catalyze the introduction of double bonds into the hydrocarbon portion of fatty acids.

Desolvation:（脱水）In aqueous solution, the release of bound water surrounding a solute.

Dextrorotatory isomer:9右旋异构体） A stercoisomer that rotates the plane of plane-polarized light clockwise.

Diabetes mellitus:（糖尿病）A metabolic disease resulting from insulin deficiency; characterized by a failure in glucose transport from the blood into cells at normal glucose concentrations.

Dialysis:（透析）Removal of small molecules from a solution of a macromolecule, by allowing them to diffuse through a semipermeable membrane into water.

Differential centrifugation:（差速离心）Separation of cell organelles or other particles of different size by their different rates of sedimentation in a centrifugal field. Differentiation:（分化）Specialization of cell structure and function during embryonic growth and development.

Diffusion:（扩散）The net movement, of molecules in the direction of lower concentration.

Digestion:（消化）Enzymatic hydrolysis of major nutrients in the gastrointestinal system to yield their simpler components.

Diploid:（二倍体）Having two sets of genetic information; describing a cell with two chromosomes of each type.

Dipole;（双极分子）A molecule having both positive and negative charges.

Diprotic acid: An acid having two dissociable protons.

Disaccharide:（二糖） A carbohydrate consisting of two covalently joined monosaccharide units.

Dissociation constant:（解离常数）(1) An equilibrium constant (K d)for the dissociation of a complex of two or more biomolecules into its components; for example, dissociation of a substrate from an enzyme. (2) The dissociation constant (Ka) of an acid, describing its dissociation into its conjugate base and a proton.

Disulfide bridge:(二硫桥)A covalent cross link between two polypeptide chains formed by a cystine residue (two Cys residues).

DNA (deoxyribonucleic acid)： A polynucleotide having a specific sequence of deoxyribonucleotide units covalently joined through 3', 5'-phosphodiester bonds; serves as the carrier of genetic information.

DNA chimera:（DNA嵌合）A DNA containing genetic information derived from two different species.

DNA cloning:Sec cloning.

DNA library:（DNA文库）A collection of cloned DNA fragments.

DNA ligase：（DNA连接酶）An enzyme that creates a phosphodiester bond between the 3' end of one DNA segment, and the 5' end of another.

DNA looping:（DNA出环）The interaction of proteins bound at distant sites on a DNA molecule so that the intervening DNA forms a loop.

DNA microarray:（DNA微阵列）A collection of DNA sequences immobilized on a solid surface, with individual sequences laid out in patterned arrays that can be probed by hybridization.

DNA polymerase:（DNA聚合酶）An enzyme that catalyzes template-dependent synthesis of DNA from its deoxyribonucleoside 5'-triphosphate precursors.

DNA replicase system：（DNA复制酶系统）The entire complex of enzymeH and specialized proteins required in biological DNA replication.

DNA supercoiling:（DNA超螺旋化）The coiling of DNA upon itself, generally as a result of bending, underwinding, or overwinding of the DNA helix.

DNA transposition:（DNA转座）See transposition.

domain:（结构域）A distinct structural unit of a polypeptide; domains may have separate functions and may fold as independent, compact units.

Double helix:（双螺旋）The natural coiled conformation of two complementary, antiparallel DNA chains.

Double-reciprocal plot:（双倒数作图）A plot, of 1/Vo versus 1/[S], which allows a more accurate determination of Vmax and Km than a plot of V versus [S]; also called the Lineweaver-Burk plot,

E

E'°: 标准还原电位See standard reduction potential.

E. coli (Escherichia coli):（大肠杆菌）A common bacterium found in the small intestine of vertebrates; the most well-studied organism.

Electrochemical gradient:（电化学梯度）The sum of the gradients of concentration and of electric charge of an ion across a membrane; the driving force for oxidative phosphorylation and photophosphorylation.

Electrochemical potential: （电化学势）The energy required to maintain a separation of charge and of concentration across a membrane.

Electrogenic:（生电的）Contributing to an electrical potential across a membrane.

Electron acceptor:（电子受体） A substance that receives electrons in an oxidation-reduction reaction.

Electron carrier:（电子载体）A protein, such as a flavoprotein or a cytochrome, that can reversibly gain and lose electrons; functions in the transfer of electrons from organic nutrients to oxygen or some other terminal acceptor.

Electron donor:（电子供体） A substance that donates electrons in an oxidation-reduction reaction.

Electron transfer:（电子转移）Movement of electrons from substrates to oxygen via the carriers of the respiratory (electron transfer) chain.

Electrophile:（亲电剂）An electron-deficient group with a strong tendency to accept electrons from an electron-rich group (nucleophile).

Electrophoresis（电泳）: Movement of charged solutes in response to an electrical field; often used to separate mixtures of ions, proteins, or nucleic acids.

Electroporation:（电穿孔法）Introduction of macromolecules into cells after rendering the cells transiently permeable by the application of a high-voltage pulse.

Elongation factors:（延长因子）Specific proteins required in the elongation of polypeptide chains by ribosomes.

Eluate:（流出液）The effluent from a chromatographic column.

Enantiomers:（对映异构体）Stereoisomers that are nonsuperimposable mirror images of each other.

End-product inhibition:See feedback inhibition.

Endergonic reaction(耗能反应): A chemical reaction that consumes energy (that is, for which ΔG is positive).

Endocrine glands:（内分泌腺）Groups of cells specialized to synthesize hormones and secrete them into the blood to regulate other types of cells.

Endocytosis:（内吞体）The uptake of extracellular material by its inclusion within a vesicle formed by an invagination of the plasma membrane.

Endonuclease:（内切核酸酶）An enzyme that hydrolyzes the interior phosphodiester bonds of a nucleic acid; that is, it acts at points other than the terminal bonds. Endoplasmic reticulum:（内质网）An extensive system of double membranes in the cytoplasm of eukaryotic cells; it encloses secretory channels and is often studded with ribosomes (rough endoplasmic reticulum).

Endothermic reaction:（吸热反应）A chemical reaction that takes up heat (that is, for which ΔH is positive).

Energy charge:（能荷）The fractional degree to which the ATP/ADP/AMP system is filled with high-energy phosphate groups.

Energy coupling:（能量偶联）The transfer of energy from one process to anotlier. Enhancers:（增强子）DNA sequences that facilitate the expression of a given gene;

may be located a few hundred, or even thousand, base pairs away from the gene. Enthalpy (H):（焓）The heat. content of a system.

Enthalpy change (ΔH): （焓变）For a reaction, is approximately equal to the difference between the energy used to break bonds and the energy gained by the formation of new ones.

Entropy(S):（熵）The extent of randomness or disorder in a system.

Enzyme：（酶）A biomolecule, either protein or RNA, that catalyzes a specific chemical reaction. It does not affect the equilibrium of the catalyzed reaction; it enhances the rate of a reaction by providing a reaction path with a lower activation energy.

Enzyme cascade:（酶级联）A series of reactions, often involved in regulatory events, in which one enzyme activates another (often by phosphorylation), which activates a third, and so on. The effect, of a catalyst activating a catalyst is a large amplification of the signal that initiated the cascade.

Epimerases:（表异构酶）Enzymes that catalyze the reversible interconveraion of two epimers.

Epimers: （表异构体）Two stereoisomers differing in configuration at one asymmetric center, in a compound having two or more asymmetric centers.

Epithelial cell:（上皮细胞）Any cell that forms part of the outer covering of an organism or organ.

Epitope:（抗原决定族）An antigenic determinant; the particular chemical group or groups within a macromolecule (antigen) to which a given antibody binds. Equilibrium:（平衡）The state of a system in which no further net change is occurring; the free energy is at a minimum.

Equilibrium constant (K'eq)（平衡常数）A constant, characteristic for each chemical reaction; relates the specific concentrations of all reactants and products at equilibrium at a given temperature and pressure.

Erythrocyte:（红细胞）A cell containing large amounts of hemoglobin and specialized for oxygen transport; a red blood cell.

Escherichia coli: See E. coli.

Essential amino acids:（必需氨基酸）Amino acids that cannot be synthesized by humans (and other vertebrates) and must be obtained from the diet.

Essential fatty acids:（必需脂肪酸）The group of polyunsaturated fatty acids produced by plants, but not by humans; required in the human diet.

Ethanol fermentation:（乙醇发酵）See alcohol fermentation.

Eukaryote:（真核生物）A unicellular or multicellular organism with cells having a membrane-bounded nucleus, multiple chromosomes, and internal organelles.

Excited state:（激发态）An energy-rich state of an atom or molecule; produced by the absorption of light energy.

Exergonic reaction:（放能反应）A chemical reaction that proceeds with the release of

free energy (that is, for which ΔG is negative).

Exocytosis:（胞泌作用）The fusion of an intracellular vesicle with the plasma membrane, releasing the vesicle contents to the extracellular space.

Exon:（外显子）The segment of a eukaryotic gene that encodes a portion of the final product of the gene; a portion that remains after posttranscriptional processing and is transcribed into a protein or incorporated into the structure of an RNA. See intron. Exonuclease:（外切核酸酶）An enzyme that hydrolyzes only those phosphodiester bonds that are in the terminal positions of a nucleic acid.

Exothermic reaction:（放热反应）A chemical reaction that releases heat (that is, for which A// is negative).

Expression vector:（表达载体）See vector.

F

Facilitated diffusion:（协助扩散）Diffusion of a polar substance across a biological membrane through a protein transporter; also called passive diffusion or passive transport.

Facultative cells:（兼性需样氧细胞）Cells that can live in the presence or absence of oxygen.

FAD (flavin adenine dinucleotide)：（黄素腺嘌呤二核苷酸）The coenzyme of some oxidation-reduction enzymes; it contains riboflavin.

Fatty acid:（脂肪酸）A long-chain aliphatic carboxylic acid found in natural fats and oils; also a component of membrane phospholipids arid glycolipids.

Feedback inhibition:（反馈抑制）Inhibition of an allosteric enzyme at the beginning of a metabolic sequence by the end product of the sequence; also known as end-product inhibition.

Fermentation:（发酵）Knergy-yielding anaerobic breakdown of a nutrient molecule, such as glucose, without net oxidation; yields lactate, ethanol, or some other simple product.

Fibroblast（成纤维细胞）A cell of the connective tissue that secretes connective tissue proteins such as collagen.

Fibrous proteins:（纤维状蛋白质）Insoluble proteins that serve in a protective or structural role; contain

polypeptide chains tliat generally share a common secondary structure. Fingerprinting:（指纹作图）See peptide mapping.

First law of thermodynamics:The law staling that in all processes, the total energy of the universe remains constant.

Fischer projection formulas:（Fischer投影式）See projection formulas.

5' end: The end of a nucleic acid that lacks a nucleotide bound at the 5' position of the terminal residue.

Flagellum:(鞭毛)A cell appendage used in propulsion. Bacterial flagella have a much simpler structure than eukaryotic flagella, which are similar to cilia.

Flavin-linked dehydrogenases:(黄素脱氢酶)Dehydrogenases requiring one of the riboflavins.

coenzymes, FMN or FAD.

Flavin nucleotides:（黄素核苷酸）Nucleotide coenzymes (FMN and FAD) containing riboflavin.

Flavoprotein(黄素蛋白) An enzyme containing a flavin nucleotide as a tightly bound prosthetic group.

Fluid mosaic model:（流动镶嵌模型）A model describing biological membranes as a fluid lipid bilayer with embedded proteins; the bilayer exhibits both structural and functional asymmetry.

Fluorescence:（荧光）Emission of light by excited molecules as they revert to the ground state,

FMN (flavin mononucleotide):（黄素单核苷酸）Riboflavin phosphate, a coenzyme of certain oxidation- reduction enzymes.

Footprinting(足迹法) A technique for identifying the nucleic acid sequence bound by a DNA-or RNA-binding protein.

Fractionation:（分级分离）The process of separating the proteins or other components of a complex molecular mixture into fractions based on differences in their physical properties, such as size, net charge, and solubility.

Frame shift:（移码）A mutation caused by insertion or deletion of one or more paired nucleotides, changing the reading frame of codons during protein synthesis; the polypeptide product has a garbled amino acid sequence beginning at the mutated codon. Free energy (G):（自由能）The component of the total energy of a system that can do work at constant temperature and pressure.

Free energy of activation ΔG? (活化自由能);See activation energy.

Free-energy change ΔG(自由能变化): The amount of free energy released (negative ΔG) or absorbed (positive ΔG) in a reaction at constant temperature and pressure.

Free radical:（自由基）See radical.

Functional group:（功能团）The specific atom or group of atoms that confers a particular chemical property on a biomolccule.

Furanose:（呋喃糖）A simple sugar containing the five-membered furan ring. Fusion protein:（融合蛋白）(1) A family of proteins that facilitate membrane fusion.

(2) The protein product of a gene created by the fusion of two distinct genes or portions of genes.

Futile cycle:（无效循环）A set of enzyme-catalyzed cyclic reactions that results in release of thermal energy by the hydrolysis of ATP.

G

G proteins:（G蛋白）A family of heterotrimeric GTP-binding proteins that act in intracellular signaling pathways. Commonly, ligand binding to a serpentine receptor induces the exchange of GTP for bound GDP, enabling the G protein to activate a downstream enzyme in a signaling pathway. G proteins have intrinsic GTPase activity, and therefore self-inactivate.

ΔG’°: (标准自由能变化) See standard free-energy change.

Gametes:（配子）Reproductive cells with a haploid gene content; sperm or egg cells. Gangliosides:（神经节苷脂）Sphingolipids, containing complex oligosaccharides as head groups; especially common in nervous tissue.

Gel filtration:（凝胶过滤）See size-exclusion chromatography.（分子排阻层析）Gene:（基因）A chromosomal segment, that codes for a single functional polypeptide chain or RNA molecule.

Gene expression:（基因表达）Transcription, and in the case of proteins, translation, to yield the product of a gene; a gene is expressed when its biological product is present and active.

Gene splicing:（基因拼接）The enzymatic attachment of one gene, or part. of a gene, to another.

General acid-base catalysis:（广义酸碱催化）Catalysis involving proton transfer(s) to or from a molecule other than water.

Genetic code:（遗传密码）The set of triplet code words in UNA (or mRNA) coding for the amino acids of proteins.

Genetic information:（遗传信息）The hereditary information contained in a sequence of nucleotide bases in chromosomal DNA or RNA.

Genetic map:（遗传图谱）A diagram showing the relative sequence and position of specific genes along a chromosome.

Genome:（基因组）All the genetic information encoded in a cell or virus. Genomic library:（基因组文库）A DNA library containing DNA segments representing all (or most) of the sequences in an organism's genome.

Genotype:（基因性或遗传型）The genetic constitution of an organism, as distinct from ils physical characteristics, or phenotype.

Geometric isomers:（几何异构体）Isomers related by rotation about a double bond; also called cis and trans isomers.

Germ-line cell (生殖系细胞) A type of animal cell that is formed early in embryogenesis and may multiply by mitosis or may produce, by meiosis, cells that develop into gametes (egg or sperm cells).

Globular proteins：（球蛋白）Soluble proteins with a globular (somewhat rounded) shape.

Glucogenic amino acids:（生糖氨基酸）Amino acids with carbon chains that can be

metabolically converted into glucose or glycogen via gluconeogenesis. Gluconeogenesis:(糖异生)The biosynthesis of a carbohydrate from simpler, noncarbohydrate precursors such as oxaloacetate（草酰乙酸）or pyruvate（丙酮酸）. Glycan:（聚糖）Another term for polysaccharide; a polymer-of monosaccharide units joined by glycosidic bonds,

Glycerophospholipid:（甘油磷脂）An amphipathic lipid with a glycerol backbone; fatty acids are ester-linked to C-l and C-2 of glycerol, and a polar alcohol is attached through a phosphodiester linkage to C-3.

Glycoconjugate:(复合糖)A compound containing a carbohydrate component bound covalently to a protein or lipid, forming a glycoprotein or glycolipids.

Glycolipid:（糖脂）A lipid containing a carbohydrate group,

Glycolysis:（糖酵解）The catabolic pathway by which a molecule of glucose is broken down into two molecules of pyruvate.

Glycoprotein(糖蛋白) A protein containing a carbohydrate group. Glycosaminoglycan:（糖胺聚糖）A heteropolysaccharide of two alternating units: one is either N-acetylglucosamine or N-acetylgalactosamine; the other is a uronic acid (usually glucuronic acid). Formerly called mucopolysaccharide.(粘多糖)

Glycosidic bonds:（糖苷键）Bonds between a sugar and another molecule (typically an alcohol, purine, pyrimidine, or sugar) through an intervening oxygen.

Glyoxylate cycle:(乙醛酸循环) A variant of the citric acid cycle, for the net conversion of acetate into succinate and, eventually, new carbohydrate; present in bacteria and some plant cells.

Glyoxysome:（乙醛酸体）A specialized peroxisome containing the enzymes of the glyoxylate cycle; found in cells of germinating seeds.

Golgi complex:（高尔基复合体）A complex membranous organelle of eukaryotic cells; functions in the

posttranslational modification of proteins and their secretion from the cell or incorporation into the plasma membrane or organellar membranes.

Gram molecular weight:（克分子重量）The weight in grams of a compound that is numerically equal to its molecular weight; the weight of 1 mole.

Grana:（基粒）Stacks of thylakoids（类囊体）, flattened membranous sacs or disks, in chloroplasts.

Ground state:（基态）The normal, stable form of an atom or molecule; as distinct from the excited state.

Group transfer potential:（基团转移力）A measure of the ability of a compound to donate an activated group (such as a phosphate or acyl group); generally expressed as the standard free energy of hydrolysis.

H

Half-life:（半衰期）The time required for the disappearance or decay of one-half of a

given component in a system.

Haploid:（单倍体）Having a single set of genetic information; describing a cell with one chromosome of each type.

Hapten:（半抗原）A small molecule which, when linked to a larger molecule, elicits an immune response.

Haworth perspective formulas:（Haworth透视式）A method for representing cyclic chemical structures so as to define the configuration of each substituent group; the method commonly used for representing sugars.

Helicase(解螺旋酶)An enzyme that, catalyzes the separation of strands in a DNA molecule before replication.

Heme:（血红素）The iron-porphyrin prosthetic group of heme proteins.

Heme protein:（血红素蛋白）A protein containing a heme as a prosthetic group. Hemoglobin:（血红蛋白） A heme protein in erythrocytes; functions in oxygen transport.

Henderson-Hasselbalch equation: An equation relating the pH, the pKa, and the ratio of the concentrations of the proton-acceptor (A+) and proton-donor (HA) species in a solution.

Hepatocyte( 肝细胞) The major cell type of liver tissue.

Heteroduplex DNA(异源双链DNA) Duplex DNA containing complementary strands derived from two different DNA molecules with similar sequences, often as a product of genetic recombination.

Heteropolysaccharide:（杂多糖）A polysaccharide containing more than one type of sugar.

Heterotroph:（异养生物）An organism that requires complex nutrient molecules, such as glucose, as a source of energy and carbon.

Heterotropic:（异促的）Describes an allosteric modulator that is distinct from the normal ligand.

Heterotropic enzyme:（异促酶）An allosteric enzyme requiring a modulator other than its substrate.

Hexose:（己糖）A simple sugar with a backbone containing six carbon atoms.

High-energy compound:（高能化合物）A compound that on hydrolysis undergoes a large decrease in free energy under standard conditions.

High-performance liquid chromatography (HPLC)：（高效液相色谱）Chromatographic procedure, often conducted at relatively high pressures, using automated equipment that permits refined and highly reproducible profiles,

Hill reaction:（希尔反应）The evolution of oxygen and the photoreduction of an artificial electron acceptor by a chloroplast preparation in the absence of carbon dioxide. Histones:（组蛋白）The family of five basic proteins that associate tightly with DNA in the chromosomes of all eukaryotic cells,

Holliday intermediate（赫利地中间物）An intermediate in genetic recombination in which two double-stranded DNA molecules are joined by virtue of a reciprocal crossover involving one strand of each molecule.

Holoenzyme:（全酶）A catalytically active enzyme including all necessary subunits, prosthetic groups, and cofactors.

Homeobox:（同源框）A conserved DNA sequence of 180 base pairs encoding a protein domain found in many proteins that play a regulatory role in development. Homeodomain:（发育同源结构域）The protein domain encoded by the homeobox. Homeostasis:（内稳态）The maintenance of a dynamic steady state by regulatory mechanisms that compensate for changes in external circumstances.

Homeotic genes:（同源框基因）Genes that regulate the development of the pattern of segments in the Drosophila body plan; similar genes are found in most vertebrates. Homologous genetic recombination:（同源遗传重组）Recombination between two DNA molecules of similar sequence, occurring in all cells; occurs during meiosis and mitosis in eukaryotes.

Homologous proteins:（同源蛋白）Proteins having sequences and functions similar in different species; for example, the hemoglobins.

Homopolysaccharide:（同多糖）A polysaccharide made up of only one type of monosaccharide unit.

Homotropic:(同促的）Describes an allosteric modulator that is identical to the normal ligand.

Homotropic enzyme:（同促酶）An allosteric enzyme that uses its substrate as a modulator.

Hormone:（激素）A chemical substance synthesized in small amounts by an endocrine tissue and carried in the blood to another tissue, where it acts as a messenger to regulate the function of the target tissue or organ.

Hormone receptor:(激素受体) A protein in, or on the surface of, target cells that binds a specific hormone and initiates the cellular response,

Hormone response element (HRE):（激素响应元件）A short (12 to 20 bp) DNA sequence to which receptors for steroid, retinoid, thyroid, and vitamin D hormones bind, altering the expression of the contiguous genes. For each hormone, there is a consensus sequence preferred by the cognate receptor.

Hyaluronic acid:（透明质酸）A high molecular weight, acidic polysaccharide typically composed of the alternating disaccharide GlcUA(β1→3)GlcNAc, Hyaluronic acid is a major component of the extracellular matrix, and forms larger complexes (proteoglycans) with proteins and other acidic polysaccharides.

Hydrogen bond:（氢键）A weak electrostatic attraction between one electronegative atom (such as oxygen or nitrogen) and a hydrogen atom covalently linked to a second electronegative atom.

Hydrolases:（水解酶）Enzymes (proteases, lipases, phosphatases, nucleases, for example) that catalyze hydrolysis reactions.

Hydrolysis:（水解）Cleavage of a bond, such as an anhydride or peptide bond, by the addition of the elements of water, yielding two or more products,

Hydronium ion:（水合氢离子）The hydrated hydrogen ion (H3O+).

Hydropathy index:（亲水指数）A scale that expresses the relative hydrophobia and hydrophilic tendencies of a chemical group.

Hydrophilic：（亲水的）Polar or charged; describing molecules or groups that associate with (dissolve easily in) water.

Hydrophobic:（疏水的）Nonpolar; describing molecules or groups that are insoluble in water.

hydrophobic interactions （疏水相互作用）The association of nonpolar groups, or compounds, with each other in aqueous systems, driven by the tendency of the surrounding water molecules to seek their most stable(disordered)state. Hyperchromic effect(增色效应)The large increase in light absorption at 260 nm occurring as a double- helical DNA is melted (unwound).

Hypoxia:（低氧）The metabolic condition in which the supply of oxygen is severely limited.

I

Immune response:（免疫反应）The capacity of a vertebrate to generate antibodies to an antigen, a macromolecule foreign to the organism.

Immunoglobulin(免疫球蛋白) An antibody protein generated against, and capable of binding specifically to an antigen.

in vitro:（体外）"In glass"; that is, in the test tube.

in vivo:（体内）"In life"; that is, in the living cell or organism.

Induced fit:（诱导契合）A change in the conformation of an enzyme in response to substrate binding that renders the enzyme catalytically active; also used to denote changes in the conformation of any macromolecule in response to ligand binding such that the binding site of the macromolecule better conforms to the shape of the ligand. Indncer:（诱导物） A signal molecule that, when bound to a regulatory protein, produces an increase in the expression of a given gene.

Induction:（诱导）An increase in the expression of a gene in response to a change in the activity of a regulatory protein.

Informational macromolecules:（信息大分子）Biomolecules containing information in the form of specific sequences of different monomers; for example, many proteins, lipids, polysaccharides, and nucleic acids.

Initiation codon（起始密码）AUG (sometimes GUG in prokaryotes); codes for the first amino acid in a polypeptide sequence: N-formylmethionine in prokaryotes, and methionine in eukaryotes.