医心医译专业英语词汇博客

 

 

 

O

Oligomer[5RligEUmE](寡聚体) A short polymer, usually of amino acids, sugars, or nucleotides; the definition of "short" is somewhat arbitrary, but usually less than 50 subunits.

Oligomeric protein (寡聚蛋白) A multisubunit protein having two or more identical polypeptide chains.

Oligonucleotide[9RligEJ5njU:kliEUtaid]（寡核苷酸）: A short polymer of nucleotides (usually less than 50).

Oligopeptide[9RligEJ5peptaid]（寡肽）A few amino acids joined by peptide bonds.

Oligosaccharide[9RligEJ5sAkEraid]（寡糖） Several monosaccharide groups joined by glycosidic bonds.

Oncogene[5RnkE7dVi:n]（致癌基因） A cancer-causing gene; any of several mutant genes that, cause cells to exhibit, rapid, uncontrolled proliferation. See also proto-

oncogene.

Open reading frame（开放阅读框） A group of contiguous nonoverlapping nucleotide codons in a DNA or RNA molecule that do not include a termination codon.

Open system（开放系统） A system that exchanges matter and energy with its surroundings. See also system.

Operator[5RpEreitE](操纵基因) A region of DNA that interacts with a represser protein to control the expression of a gene or group of genes.

Operon[5RpE7rRn]（操纵子） A unit, of genetic expression consisting of one or more related genes and the operator and promoter sequences that regulate their transcription.

Optical[5RptikEl] activity （光学活性） The capacity of a substance to rotate the plane of plane-polarized light.

Optimum[5RptimEm] pH（最适pH）The characteristic pH at which an enzyme has maximal catalytic activity.

Organelles[7R:gE5nel](细胞器) Membrane-bounded structures found in eukaryotic cells; contain enzymes and other components required for specialized cell functions.

Origin（起始位点） The nucleotide sequence or site in DNA where DNA replication is initiated.

Osmosis[Rz5mEUsis]（渗透作用） Bulk flow of water through a semi-permeable membrane into another aqueous compartment containing solute at a higher concentration.

Osmotic[Rz5mRtik] pressure（渗透压）Pressure generated by the osmotic flow of water through a semipermeable membrane into an aqueous compartment containing solute at a higher concentration.

Oxidases[5Rksideis]（氧化酶） Enzymes that catalyse oxidation reactions in which molecular oxygen serves as the electron acceptor, but neither of the oxygen atoms is incorporated into the product. Compare oxygenases.

Oxidation[（氧化作用） The loss of electrons from a compound.

Oxidation-reduction reaction: （氧化还原反应）A reaction in which electrons are transferred from a donor to an acceptor molecule; also called a redox reaction.

Oxidative phosphorylation（氧化磷酸化） The enzymatic phosphorylation of ADP to ATP coupled to electron transfer from a substrate to molecular oxygen.

Oxidizing agent (oxidant)（氧化剂） The acceptor of electrons in an oxidation-reduction reaction.

Oxygen debt[5RksidVEn det]（氧债）The extra oxygen (above the normal resting level) consumed in the recovery period after strenuous physical exertion.

Oxygenases[5RksidVineis]（加氧酶） Enzymes that catalyze reactions in which oxygen atoms are directly incorporated into tile product, forming a hydroxyl or carboxyl group. In reactions catalyzed by a monooxygenase, only one of the two 0 atoms is incorporated; the other is reduced to rLO; in reactions catalyzed by a dioxygenase, both 0 atoms are incorporated into the product. Compare oxidases.

P

Palindrome[5pAlindrEUm]（回文结构）: A segment of duplex DNA in which the base sequences of the two strands exhibit twofold rotational symmetry about an axis.

Partition coefficient [pB:5tiFEnkEUi5fiFEnt]（分配系数）: A constant that expresses the ratio in which a given solute will be partitioned or distributed between two given immiscible liquids at equilibrium.

Pathogenic[9pAWE5dVenik]（病原性的） Disease-causing.

Pentose[5pentEUs]（戊糖） A simple sugar with a backbone containing five carbon atoms.

Pentosephosphate pathway（磷酸戊糖途径）: A pathway that serves to interconvert hexoses and pentoses and is a source of reducing equivalents and pentoses for biosynthetic processes; present, in most organisms. Also called the phosphogluconate pathway.

Peptidases[5peptideis]（肽酶） Enzymes that hydrolyze peptide bonds.

Peptide（肽） Two or more ammo acids covaleiitly joined by peptide bonds.

Peptide bond（肽键） A substituted amide linkage between the a-amino group of one amino acid and the a-carboxyl group of another, with the elimination of the elements of water,

Peptide mapping（肽指纹图） The characteristic two-dimensional pattern (on paper or gel) formed by the separation of a mixture of peptides resulting from partial hydrolysis of a protein; also known as peptide fingerprinting.

Peptidoglycan[9peptidEJ5glaikAn]（肽聚糖） A major component of bacterial cell walls; generally consists of parallel heteropolysaccharides cross-linked by short peptides.

Peripheral proteins[pE5rifErEl 5prEUti:n]（外周蛋白） Proteins that are loosely or reversibly bound to a membrane by hydrogen bonds or electrostatic forces; generally water-soluble once released from the membrane.

Permeases[5pV:mieis]（透过酶） See transporters.

Peroxisome[pE5rRksisEJm]（过氧化物酶体） Membrane-bounded organelle in the cytoplasm of cukaryotic cells; contains peroxide-forming and peroxide-destroying enzymes.

pH The negative logarithm of the hydrogen ion concentration of an aqueous solution.

Phage: See bacteriophage.

Phenotype[5fi:nEtaip]（表型） The observable characteristics of an organism.

Phosphatases[5RsfEteis]（磷酸酯酶） Enzymes that hydrolyze a phosphate ester or anhydride, releasing inorganic phosphate, Pi.

Phosphodiester linkage [5fRsfEdaiist[ 5liNkidV]（磷酸二酯键） A chemical grouping that contains two alcohols esterified to one molecule of phosphoric acid, winch thus serves as a bridge between them.

Phosphogluconate [5fRsfE5glU:kEU7neit] pathway（磷酸己糖途径） An oxidative pathway beginning with glucose 6-phosphate and leading, via 6-phosphogluconate, to pentose phosphates and yielding NADPH. Also called the pentose phosphate pathway.

Phospholipid[7fRsfEU5lipid]（磷脂） A lipid containing one or more phosphate groups.

Phosphorolysis[7fRsfE5Rlisis]（磷酸解） Cleavage of a compound with phosphate as the attacking group; analogous to hydrolysis.

Phosphorylases[5fRsfEri7leis]（磷酸化酶）Enzymes that catalyze phosphorolysis (defined above).

Phosphorylation[fR7sfRri5leiFEn]（磷酸化作用） Formation of a phosphate derivative of a biomolecule, usually by enzymatic transfer of a phosphoryl group from ATP.

Phosphorylation potential (ΔGp)（磷酸化能力）: The actual free-energy change of ATP hydrolysis under the nonstandard conditions prevailing within a cell.

Photochemical [7fEUtEU5kemikEl]reaction center（光化学反应中心） The part of a photosynthetic complex where the energy of an absorbed photon causes charge separation, initiating electron transfer.

Photon[5fEUtRn]（光子）The ultimate unit (a quantum) of light energy.

Photophosphorylation[7fEUtEUfRsfEri5leiFEn]（光合磷酸化） The enzymatic formation of ATP from ADP coupled to the light-dependent transfer of electrons in photosynthetic cells.

Photoreduction[7fEUtEUri5dQkFEn]（光还原） The light-induced reduction of an electron acceptor in phot.osynthetic cells.

Photorespiration[7fEUtEU7respi5reiFEn]（光呼吸） Oxygen consumption occurring in illuminated temperate-zone plants, largely due to oxidation ofphosphoglycolate.

Photosynthesis[7fEUtEU75inWEsis]（光合作用） The use of light energy to produce carbohydrates from carbon dioxide and a reducing agent sucli as water.

Photosynthetic[7fEUtEUsin5Wetik]7 phosphorylation（光合磷酸化） See photophosphorylation .

Photosystem[7fEUtEU75sistEm]（光系统） In photosynthetic cells, a functional set of light-absorbing pigments and its reaction center.

Phototroph[5fEUtEU7trRf]（光能生物） An organism that. can use the energy of light to synthesize its own fuels from simple molecules such as carbon dioxide, oxygen, and water; as distinct from a chemotroph.

pKa: The negative logarithm of an equilibrium constant.

Plasma membrane[5plAzmE 5membrein](质膜) The exterior membrane surrounding the cytoplasm of a cell.

Plasma proteins（血浆蛋白） The proteins present in blood plasma.

Plasmalogen[plAz5mAlEdVin]（缩醛磷脂）A phospholipid with an alkenyl ether substituent on the C-l of glycerol.

Plasmid[5plAzmid]（质粒） An extrachromosomal, independently replicating, small circular DNA molecule; commonly employed in genetic engineering.

Plastid[5plAstid]（质体） In plants, a self-replicating organelle; may differentiate into a chloroplast.

Platelets[5pleitlit]（血小板） Small, enucleated cells that initiate blood clotting; they arise from cells called megakaryocytes in the bone marrow. Also known as thrombocytes.

Pleated sheet[pli:tid Fi:t]（折叠片） The side-by-side, hydrogen-bonded arrangement of polypeptide chains in the extended 0 conformation.

Plectonemic[7plektEU5nemik](具绞旋线的) A structure in a molecular polymer in which there is a net twisting of strands about each other in some simple and regular way.

Polar[5pEUlE]（极性的) Hydrophilic, or "water-loving"; describing molecules or groups that are soluble in water.

Polarity[pEU5lAriti]（极性） (1) In chemistry, the nonuniform distribution of electrons in a molecule; polar molecules are usually soluble in water. (2) In molecular biology, the distinction between the 5' and 3' ends of nucleic acids.

Poly(A) tail(多聚腺苷酸尾) A length of adenosine residues added to the 3' ends of many mRNAs in eukaryotes (and sometimes in bacteria).

Polycistronic[7pRlisis5trRnik] mRNA（多顺反子mRNA） A contiguous mRNA with more than two genes that can be translated into proteins.

Polyclonal antibodies [9pRli5klEJnEl 5Anti7bRdis](多克隆抗体) A heterogeneous pool of antibodies produced in an animal by a number of different. B lymphocytes in response to an antigen. Different antibodies in the pool recognize different parts of the antigen.

Polylinker（多连接物）A short, often synthetic, fragment of DNA containing recognition sequences for several restriction endomicleases.

Polymerase chain reaction (PCR)（聚合酶链式反应） A repetitive procedure that results in a geometric amplification of a specific DNA sequence.

Polymorphic[9pRli5mR:fik]（多态性的） Describing a protein for which amino acid sequence variants exist in a population of organisms, but the variations do not destroy the protein's function.

Polynucleotide[7pRli5njU:kljE7taid]（多核苷酸） A covalently linked sequence of nucieotides in which the 3' hydroxyl of the pentose of one nucleotide residue is joined by a phosphodiester bond to the 5' hydroxyl of the pentose of the next residue.

Polypeptide[7pRli5peptaid]（多肽） A long chain of amino acids linked by pcptide bonds; the molecular weight, is generally less than 10,000.

Polyribosome[7pRli5raibEsEUm]（多核糖体） See polysome.

Polysaccharide[pRli5sAkEraid]（多糖） A linear or branched polymer of monosaccharide units linked by glycosidic bonds.

Polysome[5pRlisEUm](polyribosome): A complex of an inRNA molecule and two or more ribosomes.

P/O ratio（磷/氧比） The number of moles of ATP formed in oxidative phosphorylation per gO^ reduced (thus, per pair of electrons passed to Oa). Experimental values used in this text are 2.5 for passage of electrons from NADH to (X, and 1.5 for passage of electrons from FADH to 0^, Some textbooks use the integral values of 3.0 and 2.0.

Porphyria[pR5fiEriE]（卟啉症）Genetic condition resulting from the lack of one or more enzymes required to synthesize porphyrins.

Porphyrin[5pR:fErin] （卟啉） Complex nitrogenous compound containing four substituted pyrroles covalently joined into a ring; often complexed with a central metal atom.

Positive cooperativity[5pRzEtiv kEJ7RpErE5tivEti]（正协同性） A phenomenon of some multisubunit enzymes or proteins in which binding of a ligand or substrate to one subunit. facilitates binding to another subunit.

Posttranscriptional processing[9pEUsttrAns5kripFEnEl prEU55sesiN]（转录后加工） The enzymatic processing of the primary RNA transcript, producing functional mRNA, tRNA, and/or rRNA molecules.

Posttranslational modification[9pEUsttrAns5leiFEnEl9mRdifi5keiFEn]（翻译后修饰） Enzymatic processing of a polypeptide chain after translation from its mRNA.

Primary structure[5praimEri 5strQktFE]（一级结构） A description of the covalent backbone of a polymer (macromolecule), including the sequence of monomeric subunits and any interchain and intrachain covalent bonds.

Primary transcript[5praimEri 5trAnskript]（原初转录本） The immediate RNA product of transcription before any posttranscriptional processing reactions.

Primase[5praimeis]（引物酶）: An enzyme that catalyzes the formation of RNA oligonucleotides used as primers by DNA polymerascs.

Primer[5praimE]（引物）A short oligomer (of sugars or nucieotides, for example) to which an enzyme adds additional monomeric subunits.

Primer terminus[5praimE 5tE:minEs]（引物末端） The end of the primer to which monomeric suhunits are added.

Primosome[5praimEsEUm]（引发体）An enzyme complex that synthesizes the primers required for lagging strand DNA synthesis.

Probe[prEUb]（探针）A labeled fragment of nucleic acid containing a nucleotide sequence complementary to a gene or genomic sequence that one wishes to detect in a hybridization experiment,

Processivity[prE5sesiviti]（持续合成能力）For any enzyme tliat catalyzes the synthesis of a biological polymer, the property of adding multiple subunits to the polymer without dissociating from the substrate.

Prochiral[prEU5tFirEl] molecule（原手性化合物） A symmetric molecule that can react asymmetrically with an enzyme having an asymmetric active site, generating a chiral product.

Projection formulas（透视式）A method for representing molecules to show the configuration of groups around chiral centers; also known as Fischer projection formulas.

Prokaryote[prEU5kAriEUt]（原核生物） A bacterium; a unicellular organism with a single chromosome, no nuclear envelope, and no membrane-bounded organelles.

Promoter[prE5mEUtE]（启动子） A DNA sequence at. which RNA polymerase may bind, leading to initiation of transcription.

Proofreading[5prU:fri:diN]（校对） The correction of errors in the synthesis of an information-containing biopolymer by removing incorrect monomeric subunits after they have been covalent.ly added to the growing polymer.

Prostaglandins[7prRstE5glAndin]（前列腺素） A class of lipid-soluble, hormonelike regulatory molecules derived from arachidonate and other polyunsaturated fatty acids.

Prosthetic[prRs5Wetik] group（辅基） A metal ion or an organic compound (other than an amino acid) that is covalently bound to a protein and is essential to its activity.

Proteasome[5prEUtiEsEUm]（蛋白酶体）Supramolecular assembly of enzymatic complexes that. function in the degradation of damaged or unneeded cellular proteins.

Protein（蛋白质）A macromolecule composed of one or more polypeptide chains, each with a characteristic sequence of amino acids linked by peptide bonds,

Protein kinases（蛋白激酶） Enzymes that transfer the terminal phosphoryl group of ATP or another nucleoside tnphosphate to a Ser, Thr, Tyr, Asp, or His side chain in a target protein, thereby regulating the activity or other properties of that protein.

Protein targeting（蛋白质分送）The process by which newly synthesized proteins are sorted and transported to their proper locations in the cell.

Proteoglycan[prEUtiE5glaikAn]（蛋白聚糖）A hybrid macromolecule consisting of a heteropolysaccharidc joined to a polypeptide; the polysaccharide is the major component.

Proto-oncogene（原癌基因） A cellular gene, usually encoding a regulatory protein, that can be converted into an oncogene by mutation.

Proton acceptor（质子受体） An anionic compound capable of accepting a proton from a proton donor; that is, a base.

Proton donor（质子供体）The donor of a proton in an acid-base reaction; that is, an acid.

Proton-motive force（质子推动力）The electrochemical potential inherent in a transmcmbrane gradient of H'1' concentration; used in oxidative phosphorylation and photophosphorylation to drive ATF synthesis.

Protoplasm[5prEUtEplAzEm]（原生质）A general term referring to the entire contents of a living cell.

Purine[5pjUEri:n]（嘌呤）A nitrogenous heterocyclic base found in nucleotides and nucleic acids; containing fused pyrimidine and imidazole rings.

Puromycin[7pjUrEU5maisn]（嘌呤霉素）An antibiotic that inhibits polypeptide synthesis by being incorporated into a growing polypeptide chain, causing its premature termination.

Pyranose[5paiLrEnEJs]（吡喃糖）A simple sugar containing the six-membered pyran ring.

Pyridine[7pirE5dainE] nucleotide（嘧啶核苷酸）A nucleotide coenzyme containing the pyridine derivative nicotinamide; NAD or NADP.

Pyridoxal[7piri5dRksAl] phosphate（磷酸吡哆醛） A coenzyme containing the vitamin pyridoxine (vitamin B(;) ; functions in reactions involving amino group transfer.

Pyrimidine[9paiL5rimidi:n]（嘧啶）A nitrogenous heterocyclic base found in nucleotides and nucleic acids.

Pyrimidine dimer（嘧啶二聚体） A covalently joined dimer of two adjacent pyrimidine residues in DNA, induced by absorption of LIV light; most commonly derived from two adjacent thymines (a thymine dimer).

Pyrophosphatase[pairEU5fRsfEteis]（焦磷酸酶） See inorganic pyrophosphatase.

Q

Quantum[5kwRntEm]（量子） The ultimate unit of energy.

Quaternary [kwE5tE:nEri]structure（四级结构）The three-dimensional structure of a multisubunit protein; particularly the manner in which the subunits fit together.

R

R group: (1) Formally, an abbreviation denoting any alkyi group. (2) Occasionally, used in a more general sense to denote virtually any organic substituent (the R groups of amino acids, for example). Racemic[rE5si:mik] mixture (racemate[5reisimeit])（外消旋化合物） An equimolar mixture of the u and L stereoisomers of an optically active compound.

Radical[5rAdikEl]（自由基） An atom or group of atoms possessing an unpaired electron; also called a free radical.

Radioactive isotope[5reidiEU5Aktiv 5aisEUtEUp]（放射性同位素）An isotopic form of an element with an unstable nucleus that stabilizes itself by emitting ionizing radiation.

Radioimmunoassay[5reidiEU7imjUnEU5Asei]（放射免疫实验）A sensitive and quantitative method for detecting trace amounts of a biomolecule, based on its capacity to displace a radioactive form of the molecule from combination with its specific antibody.

Rate constant（速度常数）The proportionality constant that relates the velocity of a chemical reaction to the concentration(s) of the reactant(s).

Rate-limiting step（限速步骤） (1) Generally, the step in an enzymatic reaction with the greatest activation energy or the transition state of highest free energy. (2) The slowest step in a metabolic pathway.

Reaction intermediate（反应中间产物） Any chemical species in a reaction pathway that has a finite chemical lifetime.

Reading frame（阅读框）A contiguous and nonoverlapping set of three-nucleotide codons in DNA or RNA.

Recombinant[ri5kRmbinEnt] DNA（重组DNA） DNA formed by the joining of genes into new combinations.

Recombination(重组)Any enzymatic process by which the linear arrangement of nucleic acid sequences in a chromosome is altered by cleavage and rejoining.

Recombinational DNA repair（重组DNA修复）: recombinational processes that are directed at the repair of DNA strand breaks or cross-links, especially at inactivated replication forks.

Redox pair（氧还对） An electron donor and its corresponding oxidized form; for example, NADH and NAD"".

Redox reaction（氧还反应）: See oxidation-reduction reaction.

Reducing agent (reductant)（还原剂） The electron donor in an oxidation-reduction reaction.

Reducing end（还原端）The end of a polysaccharide having a terminal sugar with a free anomeric carbon; the terminal residue can act aa a reducing sugar.

Reducing equivalent A general or neutral term for an electron or an electron equivalent in the form of a hydrogen atom or a hydride ion.

Reducing sugar（还原糖）A sugar in which the carbonyl Canomeric) carbon is not involved in a glycosidic bond and can therefore undergo oxidation.

Reduction[ri5dQkFFEn]（还原）Tlie gain of electrons by a compound or ion.

Regulatory[5regjUlEtEri] enzyme（调节酶）An enzyme having a regulatory function through its capacity to undergo a change in catalytic activity by allosteric mechanisms or by covalent modification.

Regulatory gene（调节基因） A gene that gives rise to a product involved in the regulation of the expression of another gene; for example, a gene coding for a represser protein.

Regulatory sequence（调节序列）A DNA sequence involved in regulating the expression of a gene; for example, a promoter or operator.

Regulon[5regjUlRn]（调节子） A group of genes or operons that are coordinately regulated even though some, or all, may be spatially distant within the chromosome or genome.

Relaxed DNA（松弛DNA）Any DNA that exists in its most stable and unstrained structure, typically B form under most cellular conditions.

Release factors（终止释放因子）See termination factors.

Releasing factors: Hypothalamic hormones lhat stimulate release of other hormones by the pituitary gland,

Renaturation[5ri:7neitFE5reiFEn]（复性） Refolding of an unfolded (denatured) globular protein so as to restore native structure and protein function.

Replication[7repli5keiFEn]（复制）Synthesis of daughter nucleic acid molecules identical to the parental nucleic acids.

Replication fork（复制叉）The Y-shaped structure generally found at the point where DNA is being synthesized.

Replicative form（复制形式） Any of the full-length structural forms of a viral chromosome that serve as distinct replication intermediates.

Replisome[5replisEUm]（复制体）The multiprotein complex that promotes DNA synthesis at the replication fork.

Repressible[ri5pesEbl] enzyme（阻遏酶） In bacteria, an enzyme whose synthesis is inhibited when its reaction product is readily available to the cell.

Repression[ri5preFEn]（阻遏） A decrease in the expression of a gene in response to a change in the activity of a regulatory protein.

Represser[ri5presE]（阻遏蛋白）The protein that binds to the regulatory sequence or operator for a gene, blocking its transcription.

Residue[5rezidjU:]（残基） A single unit within a polymer; for example, an amino acid within a polypeptide chain. The term reflects the fact that sugars, nucleotides, and amino acids lose a few atoms (generallytne elements of water) when incorporated in their respective polymers.

Respiration[7respi5reiFEn]（呼吸）Any metabolic process that leads to the uptake of oxygen and tlie release of COg.

Respiration-linked phosphorylation（呼吸链磷酸化）ATP formation from ADP and Pp driven by electron flow through a series of membrane-bound carriers, with a proton gradient as the direct source of energy driving rotational catalysis by ATPsynthase,

Respiratory chain （呼吸链） The electron transfer chain; a sequence of electron-carrying proteins that transfer electrons from substrates to molecular oxygen in aerobic cells.

Restriction endonucleases[ris5trikFEn 7endE5njU:kli7eis]（限制性内切酶） Site-specific endodeoxyribonucleases causing cleavage of both strands of DNA at points within or near the specific site recognized by the enzyme; important tools in genetic engineering.

Restriction fragment[ris5trikFEn 5frAgmEnt]（限制性片段）A segment of double-stranded UNA produced by the action of a restriction endonuclease on a larger DNA.

Restriction fragment length polymorphisms (RFLPs) （限制片段长度多态性）: Variations, among individuals in a population, in the length of certain restriction fragments within which certain genomic sequences occur. These variations result from rare sequence changes that create or destroy restriction sites in the genome.

Retrovirus[7retrEU5vaiErEs]（反转录病毒） An RNA virus containing a reverse transcriptase.

Reverse transcriptase[ri5vE:s trAns5kripteis]（反转录酶）: An RNA-directed DNA polymerase in retroviruses; capable of making DNA complementary to an RNA.

Ribonuclease[7raibEU5njU:klieis]（核糖核酸酶）A nuclease that. catalyzes the hydrolysis of certain internucleotide linkages of RNA.

Ribonucleic acid[7raibEU5njU:kliik 5Asid]（核糖核酸） See RNA.

Ribonucleotide[7raibEU5nU:kliE7taid]（核糖核苷酸）A nucleotide containing D-ribose as its pentose component.

Ribosomal RNA （rRNA）（核糖体RNA） A class of RNA molecules serving as components of ribosomes.

Ribosome[5raibEsEUm]（核糖体）A supramolecular complex of rRNAs and proteins, approximately 18 to 22 imi in diameter; the site of protein synthesis.

Ribozymes[5raibEzaim] (核酶) Ribonucleic acid molecules with catalytic activities; RNA enzymes.

Rieske iron-sulfur protein （Rieske铁硫蛋白） A type of iron-sulfur protein in which two of the ligands to the central iron ion are His side chains. These proteins act in many electron-transfer sequences, including oxidative phosphorylation and photophosphorylation.

RNA (ribonucleic acid): A polyribunucleotide of a specific sequence linked by successive 3', 5'-phosphodiester bonds.

RNA polymerase（RNA聚合酶） An enzyme that catalyzes the formation of RNA from ribonucleoside S'-triphosphates, using a strand of DNA or RNA as a template.

RNA splicing[5splaisiN]（RNA拼接）Removal of introns and joining of exons in a primary transcript.

rRNA: See ribosomal RNA.

S

S-adenosylmethionine[E9denEsilmE5WaiEni:n] (adoMet)（S-腺苷蛋氨酸或活化蛋氨酸） An enzymatic cofactor involved in methyl group transfers.

Salvage[5sAlvidV] pathway（补救途径）Synthesis of a biomolecule, such as a nucleotide, from intermediates in the degradative pathway for the biomolecule; a recycling pathway, as distinct from a de novo pathway.

Saponification[sEpRnifi5keiFEn]（皂化作用）Alkaline hydrolysis of triacylglycerols to yield fatty acids as soaps.

Sarcomere[5sB:kEmiE]（肌节）A functional and structural unit of the muscle contractile system.

Satellite[5sAt[lait] DNA（卫星DNA） Highly repeated, nontranslated segments of DNA in eukaryotic chromosomes; most often associated with the centromeric region. Its function is not clear.

Saturated[5sAtFEreitid] fatty acid (饱合脂肪酸) A fatty acid containing a fully saturated alkyl chain.

Second law of thermodynamics[5WE:mEUdai5nAmiks]（热力学第二定律）The law stating that in any chemical or physical process, the entropy[5entrEpi](熵) of the universe tends to increase.

Second messenger[5sekEnd5mesindVE]（第二信使）An effector molecule synthesized within a cell in response to an external signal (first messenger) such as a hormone.

Secondary metabolism[5sekEndEri me5tAbElizEm]（次生代谢）Pathways that lead to specialized products not found in every living cell.

Secondary structure[5sekEndEri 5strQktFE]（二级结构） The residue-by-residue conformation of the backbone of a polymer.

Sedimentation coefficient[7sedimen5teiFEn kEUi5fiFEnt]（沉降系数） A physical constant, specifying the rate of sedimentation of a particle in a centrifugal field under specified conditions.

Selectins[5si5lektin]（选择蛋白）A large family of membrane proteins, lectins [5lektin](凝集素) that bind oligosaccharides on other cells tightly and specifically, and serve to carry signals across the plasma membrane.

SELEX; A method for rapid experimental identification of nucleic acid sequences (usually RNA) that have particular catalytic or ligand-binding properties.

Serpentine receptors[5sE:pEntain ri5septEs]（蜿蜒受体） A large family of membrane receptor proteins with seven trans-membrane helical segments. These receptors often associate with G proteins to transduce an extracellular signal into a change in cellular metabolism.

Shine-Dalgarno sequence（SD序列） A sequence in an mRNA required for binding prokaiyotic ribosomes.

SH2 domain[dEU5mein] A protein domain that binds tightly to a phosphotyrosine residue in certain proteins such as the receptor tyrosine kinases, initiating the formation of a multiprotein complex that acts in a signaling pathway.

Shuttle vector[5FQtl 5vektE]（穿梭载体） A recombinant DNA vector that can be replicated in two or more different host species. See also vector.

Sickle-cell anemia[E5ni:miE]（镰刀型贫血病）A human disease characterized by defective hemoglobin molecules; caused by a homozygous allele coding for the β chain of hemoglobin.

Sickle-cell trait[treit]（镰刀性状） A human condition recognized by the sickling of erythrocytes when exposed to low oxygen tension; occurs in individuals heterozygous for the allele responsible for sickle-cell anemia.

Signal sequence[5signl 5si:kwEns]（信号序列） An amino acid sequence, often at the amino terminus, that signals the cellular fate or destination of a newly synthesized protein.

Signal transduction[5signl trAns5dQkFEn]（信号传导） The process by which an extracellular signal (chemical, mechanical, or electrical) is amplified and converted to a cellular response.

Silent mutation[5sailEnt mjU:5teiFEn]（沉默突变）A mutation in a gene that causes no detectable change in the biological characteristics of the gene product.

Simple diffusion[5simpl di5fjU:VEn]（简单扩散） The movement of solute molecules across a membrane to a region of lower concentration, unassisted by a protein transporter.

Simple protein[5simpl 5prEUti:n]（简单蛋白） A protein yielding only amino acids on hydrolysis,

Site-directed mutagenesis[7mjUtE5dVenisis]（定点突变） A set of methods used to create specific alterations in the sequence of a gene.

Site-specific recombination[5ri:kRmbi5neiFEn] （定点重组） A type of genetic recombination that occurs only at specific sequences.

Size-exclusion chromatography [saiz-iks5klU:VEn 7krEUmE5tRgrEfi]（分子排阻层析） A procedure for the separation of a mixture of molecules on the basis of size, based on the capacity of porous polymers to exclude solutes above a certain size. Also called gel filtration(凝胶过滤).

Small nuclear RNA (snRNA)（小核RNA）Any of several small RNA molecules in the nucleus; most have a role in the splicing reactions that remove introns from mRNA, tRNA, and rRNA molecules.

Somatic cells [sEU5mAtik sels](体细胞) All body cells except the germ-line cells（生殖细胞）.

SOS response（应急反应） In bacteria, a coordinated induction of a variety of genes as a response to high levels of DNA damage.

Southern blot[5sQTEn blRt]（Southern印迹法）A DNA hybridization procedure in which one or more specific DNA fragments are detected in a larger population by means of hybridization to a complementary, labeled nucleic acid probe.

Specific acid-base catalysis[spi5sifik 5Asid-beis kE5tAlisis]（狭义酸碱催化） Acid or base catalysis involving the constituents of water (hydroxide or hydronium ions).

Specific activity[spi5sifik Ak5tiviti]（比活力）The number of micromoles (μmol) of a substrate transformed by an enzyme preparation per minute per milligram of protein at 25 °C; a measure of enzyme purity.

Specific heat[spi5sifik hi:t]（比热）The amount of energy (in joules[dVjU:l]焦耳 or calories) needed to raise the temperature of 1 g of a pure substance by 1 ºC.

Specific rotation[spi5sifik rEU5teiFEn]（比旋光度）The rotation, in degrees, of the plane of plane-polarized light （平面偏振光）(D-line of sodium[5sEUdjEm]，钠的D线) by an optically active compound at 5 °C, with a specified concentration and light path.

Specificity[7spesi5fisiti]（特异性，专一性） The ability of an enzyme or receptor o discriminate among competing substrates or ligands,

Sphingolipid[9sfiNg[J5lipid]（神经鞘磷脂） An amphipathic lipid with a sphingosine（鞘氨醇） backbone to which are attached a long-chain fatty acid and a polar alcohol.

Spliceosome[slaisi5EUsEUm]（拼接体） A complex of RNAs and proteins involved in the splicing of mRNAs in eukaryotic cells.

Splicing[5spaisiN](拼接) See gene splicing; RNA splicing.

Standard free-energy change (ΔG?°)（标准自由能变化）

The free-energy change for a reaction occurring under a set of standard conditions: temperature, 298 K; pressure, 1 atm or 101.3 kPa; and all solutes at 1 M concentration. ΔG?° denotes the standard free-energy change at pH 7.0.

Standard reduction potential (?’°): The electromotive force exhibited at an electrode by 1 M concentrations of a reducing agent and its oxidized form at 25 °C and pH 7.0; a measure of the relative tendency of the reducing agent to lose electrons.

Steady state[5stedi steit]（稳态）A nonequilibrium state of a system through which matter is flowing and in which all components remain at, a constant concentration.

Stem cells（干细胞）The common, self-regenerating cells in bone marrow[5mArEu7](骨髓) that give rise to differentiated blood cells such as erythrocytes and lymphocytes.

Stereoisomers[stiEriEU5ais[m[]（立体异构体） Compounds that have the same composition and the same order of atomic connections, but different molecular arrangements.

Sterols[5ster[Ul]（固醇类）A class of lipids containing the steroid nucleus.

sticky ends（粘性末端） Two DNA ends in the same DNA molecule, or in different molecules, with short overhanging single-stranded segments that are complementary to one another, facilitating ligation of the ends; also known as cohesive[kEU5hi:siv] ends.

Stop codons（终止密码）See termination codons.

Stroma[5str[um[]（叶绿体基质）The space and aqueous solution enclosed within the inner membrane of a chloroplast, not including the contents within the thylakoid membranes.

Structural gene（结构基因）A gene coding for a protein or RNA molecule; as distinct, from a regulatory gene.

Substitution mutation（碱基替换突变） A mutation caused by the replacement of one base by another.

Substrate[5sQbstreit]（底物） The specific compound acted upon by an enzyme.

Substrate-level phosphorylation（底物水平磷酸化） Phoyphorylation of ADP or some other nucleoside 5'-diphosphate coupled to the dehydrogenation of an organic substrate; independent of the electron-transfer chain（电子传递链）.

Suicide inhibitor[5sjuisaid in5hibit[]（自杀性抑制剂） A relatively inert molecule that is transformed by an enzyme, at its active site, into a reactive substance that irreversibly inactivates the enzyme.

Supercoil[5sju:p[7kRil]（超螺旋） The twisting of a helical (coiled) molecule on itself; a coiled coil.

Supercoiled DNA（超螺旋DNA）DNA that twists upon itself because it is under- or overwound (and thereby strained) relative to B-form DNA.

Superhelical density[9sju:p[5helikEl 5densiti]（超螺旋密度）: In a helical molecule such as DNA, the number of supercoils (superhelical turns) relative to the number of coils (turns) in the relaxed molecule.

Suppressor mutation[s[5pres[ mjU:teiFEn]（抑制基因突变）A mutation that totally or partially restores a function lost by a primary mutation; located at a site different, from the site of the primary mutation,

Svedberg[5sfed7b[:g (S): (沉降系数)A unit of measure of the rate at which a particle sediments in a centrifugal field.

Symbionts[5simbaiRnt]（共生体） Two or more organisms that are mutually interdependent; usually living in physical association.

Symport[5simpR:t]（共转运）Cotransport of solutes across a membrane in the same direction.

Synthases[5sinWeis]（合酶）Enzymes that catalyze condensation reactions in which no nucleoside triphosphate is required as an energy source.

Synthetase[5sinWeteis]（合成酶）Enzymes that catalyze condensation reactions using ATP or another nucleoside triphosphate as an energy source.

System（系统）An isolated collection of matter; all other matter in the universe apart from the system is called the surroundings（环境）.

T

Telomere[5tel[mi[]（端粒）Specialized nucleic acid structure found at the ends of linear eukaryotic chromosomes.

Template[5templit]（模板） A macromolecular mold or pattern for the synthesis of an informational macromolecule.

template strand（模板链）A strand of nucleic acid used by a polymerase as a template to synthesize a complementary strand.

terminal transferase[5t[:minl 5trAnsfE7reis]（末端转移酶） An enzyme that catalyzes the addition of nucleotide residues of a single kind to the 3' end of DNA chains.

termination codons（终止密码）UAA, UAG, and UGA; in protein synthesis, signal the termination of a polypeptide chain. Also known as stop codons.

termination factors（终止因子） Protein factors of the cytosol required in releasing a completed polypeptide chain from a ribosome; also known as release factors.

termination sequence（终止序列） A DNA sequence that appears at the end of a transcriptional unit and signals the end of transcription.

Terpenes[5t[:pi:n]（萜类） Organic hydrocarbons or hydrocarbon derivatives constructed from recurring isoprene units. They produce some of the scents and tastes of plant products.

Tertiary[5t[:FEri] structure（三级结构） The three-dimensional conformation of a polymer in its native folded state.

Tetrahydrobiopterin[7tetr[7haidr[5bai[Upterin]（四氢生物喋呤）The reduced coenzyme form of biopterin（生物喋呤）.

Tetrahydrofolate[7tetr[7haidr[5fEUleit]（四氢叶酸） The reduced, active coenzyme form of the vitamin folate[ 5fEUleit](叶酸).

thiamine pyrophosphate[5Wai[mi:n 7pair[U5fRsfeit]（焦磷酸硫胺素）The active coenzyme form of vitamin B1; involved in aldehyde transfer reactions.

Thioester[7WaiEU5est[]（硫酯） An ester of a carboxylic acid with a thiol or mercaptan.

3' end: （3'端）The end of a nucleic acid that lacks a nucleotide bound at the 3' position of the terminal residue.

Thromboxanes[WrRm5bRksein]（凝血恶烷类） A class of molecules derived from arachidonate[[5rAkidRneit]（花生四烯酸） and involved in platelet aggregation during blood clotting.

Thylakoid[5WailE7kRid]（类囊体） Closed cisterna[sis5tE:nE](池), or disk, formed by the pigment-bearing internal membranes of chloroplasts.

thymine dimmer[5Waimi:n 5daim[]（胸腺嘧啶二聚体）See pyrimidine dimer.

tissue culture （组织培养） Method by which cells derived from multicellular organisms are grown in liquid media.

titration curve(滴定曲线) A plot of the pH versus the equivalents of base added during titration of an acid.

Tocopherols[t[U5kRf[r[Ul]（生育酚）Forms of vitamin E.

topoisomerases（拓扑异构酶） Enzymes that introduce positive or negative supercoils in closed, circular duplex DNA.

Topoisomers[tEUpEU5aisEUmE]（拓扑异构体）Different forms of a covalently closed, circular DNA molecule that differ only in their linking number.

Topology[t[5pRl[dVi]（拓扑学）The study of the properties of an object that do not change under continuous deformations such as twisting or bending.

Toxins[5tRksin]（毒素蛋白）Proteins produced by some organisms and toxic to certain other species.

trace element（痕量元素） A chemical element required by an organism in only trace amounts.

Transaminases[trAn5sAmineis]（转氨酶）See aminotransferases（氨基转移酶）.

Transamination[trAn7sAmi5neiF[n]（转氨作用）Enzymatic transfer of an amino group from an α-amino acid to an α-keto acid.

Transcription[trAns5kripF[n]（转录） The enzymatic process whereby the genetic information contained in one strand of DNA is used to specify a complementary sequence of bases in an mRNA chain.

transcriptional control（转录控制）The regulation of a protein's synthesis by regulation of the formation of its mRNA.

Transduction[trAns5dQkF[n][（能量）转换、（信息）传导] (1) Generally, the conversion of energy or information from one form to another. (2) The transfer of genetic information from one cell to another by means of a viral vector.

transfer RNA (tRNA)（转移RNA）A class of RNA molecules (M,. 25,000 to 30,000), each of which combines covalently with a specific amino acid as the first step in protein synthesis.

Transformation[7trAnsf[5meiFEn](转化) Introduction of an exogenous DNA into a cell, causing the cell to acquire a new phenotype.

Transgenic[trAnsdVinik]（转基因的） Describing an organism that has genes from another organism incorporated within its genome as a result of recombinant DNA procedures.

transition state （过渡态）An activated form of a molecule in which the molecule has undergone a partial chemical reaction; the highest point on the reaction coordinate(反应进程图).

Translation[trAns5leiFEn]（翻译）The process in which the genetic information present in an mRNA molecule specifies the sequence of amino acids during protein synthesis.

translational control（翻译控制） The regulation of a protein's synthesis by regulation of the rate of its translation on the ribosome.

translational repressor[ri5pres[r]（翻译阻遏物）A represser that binds to an mRNA, blocking translation.

Translocase[trAns5lEUkeis]（转运酶、移位酶） (1) An enzyme that catalyzes membrane transport. (2) An enzyme that causes a movement, such as the movement of a ribosome along an mRNA.

Transpiration[7trAnspi5reiF[n]（蒸腾作用）Passage of water from the roots of a plant to the atmosphere via the vascular[5vAskjulE] system（脉管系统） and the stomata（气孔） of the leaves.

Transporters[trAn5spR:t[]（转运体） Proteins that span a membrane and transport specific nutrients, metabolites, ions, or proteins across the membrane; sometimes called permeases (透过酶)

Transposition[7trAnsp[5ziF[n]（转座） The movement of a gene or set of genes from one site in the genome to another.

Transposon[trAns5pEUsRn] (transposable element)（转座子）A segment of DNA that can move from one position in the genome to another.

Triacylglycerol[trai7Asil5^lis[r[ul]（三酰甘油）An ester of glycerol with three molecules of fatty acid; also called a triglyceride[trai5glisEraid](三酰甘油酯) or neutral fat （中性酯）.

Tricarboxylic[trai7kB:bCk5silik] acid cycle（三羧酸循环） See citric acid cycle,

Triose[5trai[Us]（丙糖）A simple sugar with a backbone containing three carbon atoms.

tRNA: See transfer RNA.

tropic hormone (tropin)（促激素） A peptide hormone that stimulates a specific target gland to secrete its hormone; for example, thyrotropin[9WairEU5trEJpin](促甲状腺素) produced by the pituitary stimulates secretion of thyroxine[Wai5rRksi:n]（甲状腺素. 甲状腺氨酸） by the thyroid（甲状腺）.

turnover number（周转数） The number of times an enzyme molecule transforms a substrate molecule per unit time, under conditions giving maximal activity at substrate concentrations that are saturating.

U

Ubiquitin [jUbi5kwi:tin]（泛蛋白） A small, highly conserved protein that targets an intracellular protein for degradation by proteasomes. Several ubiquitin molecules are covalently attached in tandem to a Lys residue in the target protein by a specific ubiquitinating enzyme.

ultraviolet (UV) radiation[5Qltr[5vai[lit 7reidi5eiFEn]（紫外辐射） Electromagnetic radiation in the region of 200 to 400 nm.

Uncompetitive[QnkEm5petitiv] inhibition（反竞争性抑制） The reversible inhibition pattern resulting when an inhibitor molecule can bind to the enzyme-substrate complex but not to the free enzyme.

Uncoupling[5Qn5kQpliN] agent（解偶联剂） A substance that uncouples phosphorylation of ADP from electron transfer; for example, 2,4-dinitrophenol[7dai7naitrEU5fi:nRl]（2，4-二硝基苯酚）.

Uniport[5jUnipR:t]（单向转运）A transport system that carries only one solute, as distinct from cotransport,

Unsaturated[5Qn5sAtF[reitid] fatty acid（不饱合脂肪酸） A fatty acid.containing one or more double bonds.

Urea[5jU[ri[] cycle（尿素循环） A metabolic pathway in vertebrates, for the synthesis of urea from amino groups and carbon dioxide; occurs in the liver.

Ureotelic[7jUEri[U5telik]（排尿素的）Excreting excess nitrogen in the form of urea.

Uricotelic[7jU[rik[5telik]（排尿酸的） Excreting excess nitrogen in the form of urate (uric acid).

V

Vmax（最大反应速度）The maximum velocity of an enzymatic reaction when the binding site is saturated with substrate,

Vector（载体） A DNA molecule known to replicate autonomously in a host cell, to which a segment of DNA may be spliced to allow its replication; for example, a plasmid or an artificial chromosome.

Vectorial[vektErEl] metabolism（方向性代谢） Metabolic transformations in which the location (not the chemical composition) of a substrate changes relative to a cellular membrane dividing two compartments. Transporters catalyze vectorial reactions, as do the proton pumps of oxidative and photophosphorylation.

Viral[5vair[l] vector（病毒载体）A viral DNA altered so that it can act as a vector for recombinant DNA.

Virion[5vai[riRn]（病毒粒）A virus particle.

Virus[5vai[r[s]（病毒）A self-replicating, infectious, nucleic acid-protein complex that requires an intact host cell for its replication; its genome is either DNA or RNA.

Vitamin[5vait[min]（维生素） An organic substance required in small quantities in the diet of some species; generally functions as a component of a coenzyme.

W

wild type（野生型） The normal (unmutated) phenotype.

Wobble[5wCbl]（摆动、变偶） The relatively loose base pairing between the base at the 3' end of a codon and the complementary base at the 5' end of the anticodon.

X

x-ray crystallography[krist[5lRgr[fi]（X-射线晶体学）The analysis of x-ray diffraction patterns of a crystalline compound, used to determine the molecule's three-dimensional structure.

Z

Zink[ziNk] finger (锌指) A specialized protein motif[m[U5ti:f](基序) involved in DNA recognition by some DNA-binding proteins, characterized by a single atom of zinc coordinated[kEU55R:dinit](配位) to four Lys residues or to two His and two Lys residues.

Zwitterion[5tsvit[rai[n]（兼性离子）A dipolar ion, with spatially separated positive and negative charges.

Zymogen[5zaim[dVen]（酶原） An inactive precursor of an enzyme; for example, pepsinogen [pep5sin[dV[n](胃蛋白酶原), the precursor of pepsin[5pepsin]（胃蛋白酶）。