Active center.
 活性中心
 A specialized¹ region of an enzyme² where the enzyme interacts with the substrate and catalyzes⁴ its conversion⁵ to products. Many aminoacyl residues⁷ contribute to the active center.
 
Adenylyl cyclase.
 腺苷酸环化酶
 An enzyme that catalyzes the synthetic⁸ reaction of cyclic AMP from ATP in response to hormones¹⁰ such as epinephrine and glucagon.
 
Alanine-glucose¹¹ cycle.
 丙氨酸-葡萄糖循环
 A cooperative pathway between liver and muscle in which the ammonia and carbon from amino acid metabolism¹² are removed from the muscle as alanine, taken up by the liver, transaminated to pyruvate, converted into glucose, and shipped out back to the muscle.
 
albumin.
 清蛋白
 Albumin makes up 50% to 55% of the proteins of plasma¹³ and is thought to be the main contributor to osmotic pressure of blood. Another important function is that albumin has very broad and non-specific binding¹⁵ properties.
 
Allosteric enzyme.
 变构酶
 Allosteric enzymes¹⁶ are enzymes whose activity at the catalytic site may be modulated¹⁷ by the presence of allosteric effectors at an allosteric site. Allosteric means “occupy another space”, so an allosteric effector occupy another space, giving an effect on enzymes.
 
Allosteric regulation.
 变构调节
 A type of enzyme regulation in which an effector binds¹⁸ to one site on the enzyme and increase or decreases the activity at another site. Allosteric regulation provides a rapid means for regulation of their activity.
 
Aminoacyl-tRNA synthetase.
 氨基酰tRNA合成酶
 The enzymes are responsible for the recognition and attachment¹⁹ of the 20 amino acids to specific tRNA.
 
Anticodon.
 反密码子
 The template-recognition site on tRNA is a sequence of three bases called the anticodon, which recognizes a complementary sequence of three bases on mRNA.
 
Apoprotein.
 载脂蛋白
 The protein moiety²⁰ of a lipoprotein. They mediate²¹ the interaction between lipoproteins and tissues.
 
Apoptosis.
 细胞凋亡
 Programmed cell death. The programmed cell death is tightly regulated, which plays important roles in physiologic²² processes. Typical morphologic changes can be observed in apoptosis. One or more endonucleases degrade DNA²³, leading to characteristic ladder of discrete²⁴ DNA fragment on electrophoresis.
 
Bile salts.
 胆汁酸盐
 Salt form of bile acids and their conjugates²⁵. Since bile contains significant quantities of sodium²⁶ and potassium and the pH is alkaline, it is assumed that the bile acids and their conjugates are in a salt form, so called “bile salts.”
 
Biotin.
 生物素
 A cofactor involved in carboxylation reactions. Most enzymes that catalyze³ the ATP-dependent addition of CO2 to a substrate (like acetyl-CoA carboxylase) requires the cofactor biotin.
 
Calcitonin.
 降钙素
 A 32-amino-acid peptide secreted²⁷ by the parathyroid. The dominant²⁸ biological action of calcitonin is to mediate a lowering of serum²⁹ calcium³⁰ levels. The hypocalcemic and hypophosphatemic effects of calcitonin are believed to be due to an inhibition of PTH-mediated³¹ calcium resorption.
 
Calcium-binding protein.
 钙结合蛋白
 1,25(OH)2-D3 stimulates³³ gene³⁴ transcription and formation of specific mRNA that codes for “calcium-binding protein”, also called “Calbindin”. Three distinct vitamin D-induced “Calbindin” have been isolated³⁶. Two of them are found exclusively inside the intestinal³⁷ and kidney cells, which are actively³⁸ involved in calcium translocation.
 
Calmodulin.
 钙调蛋白
 A ubiquitous calcium sensor³⁹ in eukaryotes, regulates the activities of many intracellular proteins. The binding of Ca2+ to multiple sites in calmodulin induces a major conformational change that converts it from an inactive to an active form. Activated⁴¹ calmodulin binds to many enzymes and modifies their activities.
 
cAMP.
 环化腺苷一磷酸
 Second messenger for increased demand for energy and glucose. cAMP activates⁴² cAMP-dependent protein kinase. Increased cAMP levels are associated with increased protein phosphorylation. Increases in the cAMP concentration cause activation⁴³ of glycogen degradation⁴⁴, increased fatty acid breakdown⁴⁵, stimulation⁴⁶ of glycolysis in muscle, and stimulation of gluconeogenesis in the liver.
 
cAMP-dependent protein kinase，PKA.
 依赖cAMP的蛋白激酶
 Most effects of cyclic AMP in eukaryotic cells are mediated by the activation of a single protein kinase. This key enzyme is called protein kinase A or cAMP-dependent protein kinase, which alters the activities of target proteins by phosphorylating specific serine or threonine residues.
 
Capping.
 帽子生成
 Putting a 7-methylguanosine triphosphate on the 5’ end of an mRNA molecule⁴⁸. Capping is involved in the recognition of mRNA and may increase the stability of the RNA by preventing the attack of 5’exonucleases.
 
Carnitine shuttle.
 肉碱穿梭
 Gets fatty acyl groups into mitochondria. Fatty acyl-CoA in the cytosol is transferred to carnitine to make fatty acyl carnitine, which is transported into mitochondria. Once inside, the fatty acyl group is transferred to CoA and the carnitine is returned to the mitochondrial membrane⁴⁹.
Catabolic pathway.
 分解代谢途径
 Degradative metabolism. Catabolic pathways involve oxidative processes that release free energy.
 
Catabolic repression⁵⁰.
 分解代谢阻遏
 Catabolic repression means that an intermediate in a sequence of catabolic enzyme-catalyzed⁵¹ reactions has ability to repress synthesis of catabolic enzymes.
 
Catabolite gene activator⁵² protein, CAP.
 分解（代谢）物基因激活蛋白
 A cAMP-binding protein that is capable of stimulating⁵³ transcription by binding to certain promoter sites. It consists of two subunits, each of which contains a DNA-binding domain⁵⁴ and a cAMP binding domain.
 
cDNA library.
 cDNA文库
 A library is a collection of recombinant clones. cDNA library represents the population of mRNA in a tissue. See also cDNA.
 
cDNA.
 互补DNA
 Complementary DNA. cDNA copies from a population of cytoplasmic mRNA using enzyme reverse transcriptase, converting the cDNA single strands⁵⁶ to double-stranded DNA. The reverse transcriptase copies RNA templates into DNA-RNA hybrids⁵⁷. After the RNA in these hybrids is specifically destroyed, double-stranded DNA may be produced by DNA polymerase. cDNA is a copy of an mRNA so that it contains only the exon sequences.
 
cis-acting element.
 顺式作用元件
 This word described the regulatory interactions between two DNA sequences on the same gene. An enhancer or repressor sequence in the DNA is a cis-acting element or factor that affects the transcription of the gene.
 
cistron.
 顺反子
 A stretch of DNA that carries the information for a polypeptide chain is called cistron.
 
Clone.
 克隆
 Group of cells or sequences of DNA that are identical with a single parental⁵⁸ cell or molecule.
 
Coding strand⁵⁵.
 编码链
 The coding strand of DNA has the same sequence as that of the RNA transcript³⁵ except for T in place of U. It is so-called because it matches the RNA transcript that encodes the protein. The coding strand is also known as the sense strand.
 
codon.
 密码子
 Each amino acid in a protein is specified⁵⁹ by an mRNA sequence of three nucleotides, which is called a codon.
 
Coenzyme.
 辅酶
 A molecule bound to an enzyme and is essential for its activity. The coenzymes allow the enzyme to have functional⁶⁰ groups that are not available from the side chains of the amino acids.
 
Competitive inhibition.
 竞争性抑制
 Substrate and inhibitor combine at the same site and result in raising the apparent Km for the substrate.. In competitive inhibition, inhibitor can be completely displaced by a high concentration of the substrate.
 
Configuration⁶¹.
 构型
 The stereochemical arrangement of atoms in a molecule. Configuration cannot be changed without breaking and reforming covalent bonds.
 
Conformation.
 构象
 Differences in rotation⁶² around bonds. The conformation of a molecular⁶³ can be changed by simply rotating groups around single bonds.
 
Conjugated bilirubin.
 结合胆红素
 Adding glucuronic  acid molecules⁶⁴ to bilirubin. Hepatocytes perform the process and convert bilirubin to a  water-soluble⁶⁵ form.
 
Cosmid vector.
 柯斯质粒载体
 A special class of artificially constructed E.coli plasmids that carry the λ cos site, which allows them to be packaged intoλphage particles for efficient introduction into bacteria.
 
Creatine kinase.
 肌酸激酶
 Kinases incorporate phosphate from ATP into the substrate. Creatine kinase converts creatine to creatine phosphate, a major energy reserves in muscle.
 
de novo synthesis.
 从头合成
 Biosynthesis of nucleotides with simple materials. Purine and pyrimidine ribonucleotides are synthesized via two pathways, in which the purines are built as nucleotides via phosphoribosyl intermediates, whereas the pyrimidine ring is completed to the stage of orotate before coupling to ribose.
 
degenerate.
 简并
 More than one codon can specify⁶⁶ the same amino acid and all codons are unambiguous in that each specifies⁶⁷ no more than one amino acid.
 
Denaturation.
 变性
 Destroy the secondary, tertiary, and quaternary structure of a protein, DNA, or RNA molecule.
 
DNA damage.
 DNA损伤
 DNA damage is that changes in the DNA sequence resulted from copying errors and the effects of various physical and chemical agents or carcinogens，which alters one or more nucleotides in DNA.
 
DNA polymerase.
 DNA聚合酶
 The principal synthetic enzyme, DNA polymerase, extends the primers in the 5’ to 3’ direction by catalyzing⁶⁸ addition of deoxyribonucleoside 5’-phosphates to the primer 3’ends. Synthesis proceeds in the 5’ to 3’ direction as the template strand is read in the 3’ to 5’ direction.
 
DNA Replication. 
 DNA复制
 Generation of a new copy of double-stranded DNA from a parental DNA molecule.
 
Domain.
 结构域
 Some polypeptide chains fold into two or more compact supersecondary structures. These compact globular supersecondary structures are called domains⁶⁹, which is one level of protein’s structures between secondary structure and tertiary structure.
Effector.
 效应剂
 A class of small molecules capable of binding at a regulatory site. The binding of an effector changes the conformation of the enzyme so as to alter the kinetic⁷⁰ properties of the catalytic site.
 
Enhancer.
 增强子
 The sequence elements that can increase the rate of transcription initiation⁷¹ of eukaryotic genes⁴⁷. Enhancers have no promoter activity of their own but they can exert their stimulatory⁷² actions over distances of several thousand base pairs.
 
Enterohepatic circulation.
 肠肝循环
 The primary bile acids are synthesized in the liver and the secondary bile acids are formed in the intestine⁷³. The secondary bile acids are absorbed in the intestine, returning to the liver then recycle between intestine and liver, which is known as the entero-hepatic circulation.
 
Epidermal⁷⁴ growth factor (EGF) .
 表皮生长因子
 Epidermal growth factor can stimulates growth of many epidermal and epithelial cells.  Also see  “growth factor”.
 
Essential amino acid.
 必需氨基酸
 The amino acids that humans can not synthesize. The human diet must contain these amino acids to support growth or maintain health.
 
exon.
 外显子
 Regions that are retained in the mature RNA.
 
FAD⁷⁵.
 黄素腺嘌呤二核苷酸
 Flavin Adenine Dinucleotide.  FAD is derived⁷⁶ from vitamin riboflavin, which serves as cofactor for oxidation and reduction reactions.
 
Fat.
 脂肪
 Mainly stored as triglyceride in adipose⁷⁷ tissue. The adipose tissue releases fatty acids by the activation a hormone⁹-sensitive lipase that catalyzes the hydrolysis of the triglyceride. The fatty acids are then transported through the serum and oxidized via b oxidation in the tissues to yield energy.
 
Feedback inhibition .
 反馈抑制
 Feedback inhibition refers to the inhibition of the activity of an enzyme in a biosynthetic pathway by an end product of that pathway.
 
Ferritin.
 铁蛋白
 Intracellular form of iron storage. It stores iron that can be used as condition requires.
 
FH4.
 四氢叶酸
 Tetrahydrofolate. A reduced form of folic acid involved intimately in one-carbon transfer reactions.
 
Gene.
 基因
 A stretch of DNA that carries the information for a polypeptide chain is called gene or cistron.  Also see cistron.
 
Genome.
 基因组
 Total information of gene contained in a cell, an organism or a virus.
 
Genomic DNA library.
 基因组DNA文库
 Fragments of DNA from the genome of some organism. They are prepared from the total DNA of a cell line or tissue by performing partial digestion⁷⁸ of total DNA with a restriction⁷⁹ enzyme that cuts DNA frequently. It contains exons, introns, untranslated regions that can occur in DNA.
 
Glucogenic amino acid.
 生糖氨基酸
 The amino acid that yield pyruvate or citric cycle intermediates.
 
Gluconeogenesis.
 糖异生
 Making glucose or glycogen from noncarbohydrate. The term used to include all mechanisms⁸⁰ and pathways responsible for converting noncarbohydrate to glucose or glycogen.
 
Glycerol-a-phosphate shuttle. 
 a-磷酸甘油穿梭
 Get electron from cytoplasmic NADH into the mitochondria so that 2 ATPs can be made by oxidation of the NADH. The enzymes of the shuttle in mitochondria is linked to the respiratory chain via a flavoprotein.
 
Glycolysis.
 酵解
 Metabolic⁸¹ pathway that provides pyruvate as fuel to the citric cycle or for fat synthesis. In the absence of oxygen, lactate is produced from the pyruvate to regenerate⁸² NAD+ so that the pathway can continue to work in the absence of oxygen.
 
Gout.
 痛风
 It is an inherited metabolic disease that affects the joints⁸³ and kidneys caused by hyperuricemia. Though some patients have a partial deficiency of hypoxanthine-guanine phosphoribosyl transferase (HGPRT),  it is not sole cause of the disease.
 
Growth factor.
 生长因子
 Small polypeptides (more properly called cytokines) that stimulate³² the growth of particular classes of cells. The factors have a variety of effects, including changes in the uptake of small molecules, initiation or stimulation of the cell cycle, and ultimately cell division. Examples of secreted cytokines are EGF (epidermal growth factor), PDGF (platelet-derived growth factor), and insulin.
 
Guide RNA.
 指导RNA
 Guide RNA is a sequence that is complementary to the correctly edited mRNA.
 
Hairpin structure.
 发夹结构
 A double-helical stretch formed by base paring between neighboring complementary sequences of a single strand of DNA or RNA.
 
Helicase.
 解链酶
 An enzyme whose activity involved in DNA replication that relieves the strain associated with unwinding the DNA double helix during replication.
 
Heme.
 血红素
 A cofactor consisting of a porphyrin ring containing an iron atom. Heme has different functions depending on the protein that used them as a cofactor. Heme are used to carry oxygen without oxidizing it in hemoglobin and myoglobin, but in other proteins, like cytochrome P450, the heme iron produces a very reactive iron-oxygen species at the active site.
Hemoglobin. 
 血红蛋白
 Hemoglobin is the oxygen-carrying system found in erythrocytes, which transports oxygen from the lungs to all tissues of the body. The quaternary structure of hemoglobin confers its allosteric properties that adapt it to its biologic roles and permit its precise regulation.
 
Hexokinase.
 己糖激酶
 Responsible for the phosphorylation of glucose for entry into glycolysis, glycogen synthesis, or the pentose phosphate pathway.
 
hnRNA.
 不均一核内RNA
 Heterogeneous nuclear RNA. They are formed in the nucleus⁸⁴ that is a precursor⁸⁵ to mRNA, which has both the intron and exon sequences.
 
Hormone response element, HRE.
 激素反应元件
 A specific DNA sequences capable of binding activated receptors.  These elements regulate the gene expression. Both steroids and peptide hormones exert their effects on transcription through HREs, but the initial reactions are different.
 
Housekeeping gene.
 管家基因
 The genes that are expressed at a reasonably constant rate and not known to be subject to regulation.
 
Induction.
 诱导
 Synthesis of a particular protein in response to a signal stimulation in cellular⁴⁰ metabolism. For example, the synthesis of an enzyme can be induced by its substrate.
 
Intron.
 内含子
 The mosaic⁸⁶ nature of eukaryotic genes is discontinuous. The primary transcript of a gene contains the regions that are not present in the mRNA. Regions that are removed from the primary transcript are called introns.
 
Isoelectric point. 
 等电点
 The pH at which a molecule has a net zero charge.
 
Isomerase.
 异构酶
 An enzyme that catalyzes an intramolecular rearrangement.
 
Isozyme.
 同工酶
 Distinct physical forms of an enzyme with the same catalytic activity. Separation and identification of isozymes is of diagnostic value.
 
Jaundice.
 黄疸
 When bilirubin in the blood reaches a certain concentration, hyperbilirubinemia exists and bilirubin diffuses⁸⁷ into the tissues, which then became yellow. The condition is called jaundice.
 
Ketogenic amino acid.
 生酮氨基酸
 An amino acid that yields only acetyl-CoA. They can not yield pyruvate or tricarboxylic acid cycle intermediates.
 
Ketone bodies.
 酮体
 Acetoacetate, hydroxybutyrate and acetone. At high rate of fatty acid oxidation, the liver produces considerable quantities of acetoacetate and hydroxybutyrate. The former continually undergoes spontaneous decarboxylation to yield acetone.  Ketone bodies are metabolized in muscle and brain as an energy source.
 
Km.
 米氏常数
 If an enzyme follows hyperbolic kinetics, the Km is equal to the substrate concentration at which the reaction rate is half its maximal value.
 
Ligase.
 连接酶
 A ligase catalyzes the joining of two pieces of DNA covalently. DNA ligase joins the backbone⁸⁸ phosphates in a phosphodiester bond.
 
Lipids.
 脂类
 Lipids consist of a diverse set of hydrophobic molecules including triglycerides, phospholipids, steroids, and so forth⁸⁹.  It is soluble in organic solvents⁹⁰ like chloroform or ether.
 
Malate-Aspartate shuttle.
 苹果酸-天冬氨酸穿梭
 Gets electrons from cytoplasmic NADH into the mitochondria so that 3 ATPs can be produced by oxidation of the NADH.
 
Mitogen-activited-protein kinase ( MAPK).
 有丝分裂原激活蛋白激酶
 Mitogen-activated protein kinase (MAPK) is one of the most ancient signaling molecules and is involved in multiple cellular processes, including cell proliferation, cell growth, and cell death.
 
Messenger RNA (mRNA).
 信使RNA
 The RNA in cytoplasm that serve as templates for protein synthesis. The primary RNA transcript is processed to mRNA by adding a cap and a tail and removing introns.
 
NAD+-NADH.
 辅酶I
 Nicotinamide adenine dinucleotide. NADH is an electron carrier. NAD+ accepts two electrons and a proton from substrates and ultimately transfers them to the electron transport chain to make three ATPs and H2O.
 
Nicotinic acid.
 尼克酸
 A vitamin that serves as a source of the pyridine ring of NAD+ and NADP+. Dietary deficiency of nicotinic acid can lead to pellagra. Humans can synthesize nicotinic acid that derived from tryptophan.
 
Non-competitive inhibition.
 非竞争性抑制
 In non-competitive inhibition, inhibitor bind¹⁴ to a different domain of an enzyme, lowering the maximum velocity⁹¹ but with normal Km.
 
Nucleosides.
 核苷
 A nucleoside consists of a purine or pyrimidine base linked to a pentose.
 
Nucleotides.
 核苷酸
 A nucleotide is a phosphate ester of a nucleoside on 3’- or 5’-carbon of ribose. Phosphorylation on 5’-carbon of ribose is the one most commonly esterified forms.
 
Okazaki fragment.
 冈崎片段
 The short discontinuous segments, which later are joined by DNA ligase, are called Okazaki fragment after their discoverer.
Oncogene.
 癌基因
 Oncogenes are the genes capable of changing a normal cell into a transformed cells. Many oncogenes encode abnormal signal transduction proteins involved in imitating the action of polypeptide growth factor.
 
Operator.
 操纵序列
 The operator is a DNA segment adjacent to the structural⁹² genes. The binding of the repressor to the operator prevents the transcription of these genes.
 
Operon.
 操纵子
 A collection of prokaryotic structural genes that are present in a linear array and whose expression is controlled by the same regulatory region of the DNA. This arrangement allows simple control over the expression of proteins that are all needed for a common job. It should be noted⁹³ that an operon includes both operator and its associated structural genes.
 
Osteomalacia.
 软骨病
 Osteomalacia is caused by vitamin D deficiency in the adult, which leads to softening⁹⁴ and weakening of bones.
 
Oxidation.
 氧化
 When something is oxidized, something else must become reduced. With removal of an electron, ferrous is oxidized to ferric ion. So oxidation is a process with the loss of electrons.
 
Oxidative phosphorylation.
 氧化磷酸化
 The process in which ATP is formed as a result of the transfer of electrons from NADH or FADH2 to oxygen by a series of electron carriers.
 
Parathyroid hormone (PTH) .
 甲状旁腺素
 Parathyroid hormone, an 84-amino acid-containing protein, is secreted by the chief cells of the parathyroid gland⁹⁵. The biological actions of PTH are related to regulate calcium metabolism.
 
Pentose phosphate pathway.
 磷酸戊糖途径
 An alternative route for the metabolism of glucose. The pathway generates both NADPH for reductive syntheses and ribose residues for nucleotide biosynthesis.
 
Peptide bond.
 肽键
 The bond that the a-carboxyl group of one amino acid is joined to the a-amino group of another amino acid by an amide bond in a polypeptide.
 
Phospholipase C.
 磷脂酶C
 The activation of the phospholipase C is mediated by G protein.  The active form of the enzyme catalyzes the hydrolysis of a membrane-bounded substrate to form two second messengers, diacylglyceride and inositol 1,4,5-triphosphate. Diacylglyceride is capable of activating⁹⁶ protein kinase C. Inositol 1,4,5-triphosphate is effective for the release of calcium from intracellular calcium pool.
 
Plasmid.
 质粒
 Independently replicating⁹⁷ circular pieces of DNA whose natural function is to confer antibiotic⁹⁸ resistance to the host cell.
 
Platelet-derived growth factor.
 血小板源生长因子
 Platelet-derived growth factor can stimulates growth of messenchymal and glial cells.  Also see “growth factor”.
 
Point mutation⁹⁹.
 点突变
 It is cause by a single base change of DNA gemone, which in turn results in a change in the messenger RNA, a structural abnormality of gene expression.
 
Polycistronic mRNA.
 多顺反子mRNA
 A single mRNA that encodes more than one separately translated protein is referred to as a polycistronic mRNA, which contains multiple independent translation start and stop codons for each cistron.
 
Polypeptide chain.
 多肽链
 Many amino acids joined by peptide bonds form a polypeptide chain, which has two different ends, i.e. N-terminal and C-terminal respectively.
 
Polyribosome.
 多核糖体
 An mRNA molecule with many ribosomes bound to it. Many ribosomes can translate the same mRNA simultaneously¹⁰⁰.
 
Primary transcript.
 初级转录本
 Primary transcript is the original unmodified RNA product corresponding to a transcription unit.
 
Primase.
 引物酶
 Primase catalyzes polymerization of ribonucleoside 5’-triphosphates to form RNA primers. The sequence of monomer addition is dictated¹⁰¹ by a template strand of DNA and the chain lengths of primers are usually 10-50 nucleotides.
 
Promoter.
 启动子
 Promoter is a region of DNA involved in binding of RNA polymerase to initiate¹⁰² transcription.
 
Prosthetic group.
 辅基
 Many proteins require tightly bound, specific nonpolypeptide units for their biological activities. Such a unit is called a prosthetic group.
 
Protease.
 蛋白酶
 An enzyme that hydrolyzes the amide bonds in a protein. Most proteases recognize a specific type of amino acid side chain and cleave¹⁰³ the protein at specific points.
 
Proto-oncogene.
 原癌基因
 Normal cellular genes with the potential to become oncogenes are called proto-oncogenes or cellular oncogenes. These genes were conserved¹⁰⁴ in a wide range of eukaryotic cells. The conserved sequences were important components¹⁰⁵ of normal cells and their products are believed to play important roles in normal differentiation¹⁰⁶ and other cellular process.
 
Pyridoxal phosphate.
 磷酸吡多醛
 All transamination reactions require the coenzyme pyridoxal phosphate. The important functional groups of the coenzyme are the aldehyde group, which can form a Schiff base with the a-amino group of an amino acid and facilitate transamination.
Rate-limiting enzyme.
 限速酶
 Enzymes catalyzing committed steps in unidirectional anabolic and catabolic pathways, which act as natural governors of metabolic flow and represent the most efficient regulatory intervention¹⁰⁷.
 
Receptor.
 受体
 All of receptors are proteins that can selectively bind specific molecule and initiate their biologic effects.
 
Recombinant DNA.
 重组DNA
 Information exchanging by breaking and joining chromosomal¹⁰⁸ DNA. Recombination can occur between genes with similar sequences or between genes with different sequences.
 
Reduction.
 还原
 Chemically, reduction is defined as the gain of electrons. NAD+ is reduced to NADH. It follows that reduction is accompanied by oxidation of an electron donor¹⁰⁹.
 
Replication.
 复制
 Generation of a new copy of double-stranded DNA from a parental DNA molecule.
 
Residue⁶.
 残基
 In a polypeptide chain, an amino acid unit is called a residue.
 
Respiratory chain.
 呼吸链
 Exists in the mitochondria, consists of a number of redox carriers. The respiratory chain provides most of the energy captured in metabolism.
 
Restriction endonuclease.
 限制性内切核酸酶
 The classes of endonucleases cut DNA at specific DNA sequences within the molecule.
 
Reverse transcriptase.
 反转录酶
 An RNA-directed DNA polymerase in retroviruses; capable of making DNA complementary to an RNA.
 
Reverse transcription.
 反转录
 RNA-directed synthesis of DNA, catalyzed by reverse transcriptase.
 
Ribosomes.
 核糖体
 Complex cytoplasmic particles each consisting of two ribonucleoprotein subunits. Translation of mRNA occurs on it.
 
Ribozyme.
 核酶
 A class of RNAs that meet all the classic criteria¹¹⁰ for definition as enzymes. These catalytic RNAs catalyze highly specific hydrolysis of phosphodiester bonds in RNAs and are important in the processing events involved in maturation of pre-mRNA.
 
Rickets¹¹¹.
 佝偻病
 Vitamin D deficiency in childhood produces rickets characterized by low plasma calcium and phosphorus levels and by poorly mineralized bone with associated skeletal deformities.
 
RNA editing.
 RNA 编辑
 The information content of some mRNA is altered following transcription by process other than RNA splicing¹¹².
 
RNA Polymerase.
 RNA聚合酶
 RNA Polymerase is an enzyme that synthesizes RNA using a DNA template.
 
rRNA.
 核蛋白体rRNA
 Ribosomal RNA.  Structural components of ribosomes. There are several discrete size classes of rRNA, usually referred to by their sedimentation¹¹³ coefficients as 5S, 5.8S, 18S, and28S in eucaryotic cells.
 
S-adenosyl methionine, SAM.
 S腺苷蛋氨酸
 SAM is a major donor of one-carbon unit at the methyl oxidation state, which is formed from methyl-THF and homocysteine by a vitamin B12-dependent reaction.
 
Salting out.
 盐析
 The solubility¹¹⁴ of the proteins is lowered at high salt concentrations, so-called the “salting out”. It can be used to fractionate proteins because the dependence¹¹⁵ of solubility on salt concentration differs from one protein to another.
 
Salvage pathway.
 补救合成途径
 The pathways that purines and pyrimidines derived from nucleic acid catabolism react with PRPP and form the corresponding ribonucleotides. Corresponding deoxyribonucleotides are produced by reduction of the ribonucleoside diphosphates, using NADPH as the reducing agent.
 
Semiconservative replication.
 半保留复制
 DNA replication follows a law called semiconservative replication, i.e., one of the strands of each daughter DNA molecule is newly synthesized, whereas the other is passed on unchanged from the parent DNA molecule.
 
Sigma factor.
 σ因子
 Sigma factor is the subunit of bacterial¹¹⁶ RNA polymerase needed for initiation. It is the major influence on selection of binding sites (promoters).
 
Signal transduction.
 信号转导
 The process by which an extracellular signal is amplified¹¹⁷ and converted to a cellular response.  For example, growth factors act on the cell cycle and mitosis via transmembrane signal transduction.
 
snRNA.
 小核RNA
 Small nuclear RNA. They have roles in RNA processing but are not directly involved in protein synthesis.
 
Splicing.
 剪接
 Splicing describes the removal of introns and joining of exons in RNA; thus introns are spliced¹¹⁸ out,  while exons are spliced together.
 
Substrate.
 底物
 Reagent in a catalytic reaction by an enzyme.
 
Synthase.
 合酶
 A synthase is an enzyme that makes something but doesn’t directly require the hydrolysis of ATP to do it.
 
Synthetase.
 合成酶
 A synthetase requires the hydrolysis of ATP to make the reaction go.
 
Telomere.
 端粒
 Specialized structure at the ends of chromosomes¹¹⁹ that allows replication of the extreme 5’ ends of the DNA without loss of genetic¹²⁰ information.
Template strand.
 模板链
 The template strand, also known as the antisense strand, is one strand that the genetic information resides in the sequence of nucleotides in the double-stranded DNA molecules. This is the strand of DNA that is copied during nucleic acid synthesis.
 
Terminator.
 终止子
 Terminator is a sequence of DNA , represented at the end of the transcript, that causes RNA polymerase to terminate transcription.
 
Thiamine pyrophosphate, TPP.
 焦磷酸硫胺素
 It is derived from the vitamin thiamine, which is required for decarboxylation of a-keto acids and also involved in some transfer reactions of aldehyde derivatives¹²².
 
Topoisomerase.
 拓扑异构酶
 Enzymes that catalyze topologic changes of DNA are called topoisomerases, which can relax or insert supercoils. Topoisomer of DNA can be interconverted only by cutting one or both DNA strands and then rejoining them.
 
trans-acting factor.
 反式作用因子
 Trans-acting factor is used to describe the effect of a product from one gene on the transcription of another gene.
 
Transamination.
 转氨基作用
 The amino acid are degraded via reaction of transamination, in which the a-amino group is transferred to a acceptor a-ketoacid with production of the a-keto derivative¹²¹ of the amino acid.
 
Transcription.
 转录作用
 The synthesis of RNA using a DNA template. RNA polymerase catalyzes the synthesis and uses the antisense strand as a template.
 
Transferrin.
 运铁蛋白
 Transferrin carries two ferric ions and transfer them to cells having receptors for transferrin. Association with transferrin diminishes the potential toxicity¹²⁴ of free iron and directs iron to where it is required in the body.
 
Translation.
 翻译
 The synthesis of protein directed by the nucleotides sequence of an mRNA. Translation occurs on ribosomes.
 
Triglyceride.
 甘油三酯
 Also called triacylglycerol. It is formed by glycerol molecule and three fatty acid chains, which attached through ester linkages¹²⁵.
 
tRNA.
 转运RNA
 Transfer RNA. They serve as adaptor for the translation of the information in the sequence of nucleotides of the mRNA into specific amino acids.
 
Ubiquinone.
 泛醌
 A redox carrier presented in the respiratory chain, which is also called coenzyme Q. It exists in mitochondria, linking the flavoproteins to cytochrome b.
 
Uncouples.
 解偶联
 Allow protons back into the mitochondria without making any ATP.
 
Upstream.
 上游
 Upstream identifies sequence proceeding¹²⁶ in the opposite direction from expression; for example, the bacterial promoter is upstream of the transcription unit, the initiation codon is upstream of coding region.
 
Urea cycle.
 尿素循环
 The pathway that excess ammonia produced by deamination is excreted after conversion to urea is called urea cycle. Since urea synthesis converts toxic¹²³ ammonia to nontoxic urea, the defects in urea synthesis result in ammonia intoxication¹²⁷.
 
Vectors.
 载体
 Something that can be used to introduce recombinant DNA into a host organism. An insert is the piece of DNA that has been placed into the vector.
 
Vitamin B12. 
 维生素B12
 This vitamin is synthesized exclusively by microorganisms. In animals, it is conserved in the liver. The absorption of vitamin B12 in the intestine is mediated by receptor sites,  i.e., intrinsic factor. In clinic, deficiency of vitamin B12 can lead to anemia¹²⁸.
 
Vitamin D.
 维生素D
 Cholesterol¹²⁹ is the precursor of vitamin D. By various metabolic changes in the body, cholesterol is converted into calcitiol, which plays an essential role in the control of calcium and phosphorus metabolism.
 
Zwitterion.
 兼性离子
 An amino acid exhibits dipolar ions (Zwitterion) rather than un-ionized molecules at suitable pH. In the dipolar form of an amino acid, the amino group is protonated and the carboxyl group is dissociated so that a molecule has zero charge.
 
ρ factor.
 ρ因子
 Rho factor is a protein involved in assisting E.coli RNA polymerase to terminate transcription at certain (rho-dependent) sites.

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