1、Elements in cellsMacroelements：C、H、 O 、 NMinor elements： P、S、 Na、 Mg、 Cl、 K、 Ca Trace elements：0.1%2Molecules in cellsSmall Molecules: Small Inorganic Molecules: Water、Inorganic Salt Small Organic Molecules: Monosaccharide 、Fatty Acid、 Amino Acid、NucleotideBiomacromolecule: Polysaccharides、Lipoid 、P

2、rotein、Nucleic Acid A molecule is defined as a cluster of atoms held together by covalent bond.3Table 2-3 Molecular Biology of the Cell ( Garland Science 2008)The composition of a living cell is similar；Bacteria is the smallest and simplest cell。4Figure 2-29 Molecular Biology of the Cell ( Garland S

3、cience 2008)Macromolecules are abundant in cells5I. Small Molecules in cellsSmall Inorganic Molecules: Water Inorganic Salt Small Organic Molecules: Monosaccharide Fatty Acid Amino Acid Nucleotide61. Water - medium for lifeWater is the most abundant substance in cell, about70%. Most intracellular re

4、actions occur in an aqueous environment.Water is a polar molecule and has exceptional capacity for forming hydrogen bonds.Functions: solvent、thermoregulation、 reactant or product, etc.7Water is a polar moleculeHydrogen bond89Hydrophilic MoleculesMolecules containing polar bonds can form hydrogen bon

5、ds with water and dissolve in water.Molecules carrying negative or positive charges(ions) can interact with water, such as polysaccharides , protein , nucleic acid .10Molecules are uncharged. Molecules form few or no hydrogen bonds and do not dissolve in water, such as lipoid.Hydrophobic Molecules11

6、About 1%。Exist as ions in cells： Positive Ions：Na+、 K+ 、Ca2+ 、Fe2+、 Mg2+ Negative Ions： Cl-、SO42-、PO43-2. Inorganic SaltFunctions: Determine cell osmotic pressure and pH, participate in cell metabolism and signal transduction12Ion Concentration Determine the Cell Osmotic Pressure13Ions Paticipate in

7、 Glucose Transportation14Ions Form Membrane potential and Conduct Electrical Excitation15Molecular Weight：100-1000Da(1)Monosaccharide(2)Fatty Acid(3)Amino Acid(4)Nucleotide3. Small Organic Molecules16（1） MonosaccharideGeneral Formula: (CH2O)n，n=3,4,5,6,7,8Hexose：Glucose，Galactose，MannosePentose: Rib

8、ose，DeoxyriboseHexose is the basic unit of polysaccharide;Pentose is the component unit of nucleotides.17Isomers with formula C6H12O6GlucoseGalactoseFructose18Pentose19（2）Fatty acidAliphatic carboxylic acids，CH3(CH2)nCOOHLong Hydrocarbon chain(hydrophobic) + Carboxyl Group(hydrophilic)Covalently lin

9、ked to other molecules by carboxylic acid groupFunctions：components of cell membranes， source of energy20saturated fatty acidunsaturated fatty acidSaturated fatty acids contain no double bonds.Unsaturated fatty acids contain one or more double bonds.21Fatty Acids are named after corresponding hydroc

10、arbons.（ or n systematic nomenclature)FamiliesFatty Acids-7（n-7）palmitoleic acid（16：1，-7）-9（n-9）oleic acid（18：1，-9）-6（n-6）linoleic acid（18：2，-6，9）-3（n-3）-linolenic acid（18：3，-3，6，9）3、6 and 9 unsaturated fatty acids can not convert to each other in vivo.6 and 3 fatty acids are essential fatty acids f

11、or animals.22Number of C Atoms and Number and Position of Common Double BondsFamily Common NameSystematic NameOccurrenceMonoenoic acids (one double bond)16:1;97Palmitoleic軟脂酸cis-9-HexadecenoicInnearlyallfats.18:1;99Oleic油酸cis-9-OctadecenoicPossiblythemostcommonfattyacidinnaturalfats;particularlyhigh

12、inoliveoil.18:1;99Elaidic反油酸trans-9-Octadecenoic Hydrogenatedandruminantfats.Dienoic acids (two double bonds)18:2;9,126Linoleic亞油酸all-cis-9,12-OctadecadienoicCorn,peanut,cottonseed,soybean,andmanyplantoils.Trienoic acids (three double bonds)18:3;6,9,126-Linolenic亞麻酸all-cis-6,9,12-OctadecatrienoicSom

13、eplants,eg,oilofeveningprimrose,borageoil;minorfattyacidinanimals.18:3;9,12,153-Linolenic亞麻酸all-cis-9,12,15-OctadecatrienoicFrequentlyfoundwithlinoleicacidbutparticularlyinlinseedoil.Tetraenoic acids (four double bonds)20:4;5,8,11,146Arachidonic花生四烯酸all-cis-5,8,11,14-EicosatetraenoicFoundinanimalfat

14、s;importantcomponentofphospholipidsinanimals.Pentaenoic acids (five double bonds)20:5;5,8,11,14,173Timnodonic(EPA)all-cis-5,8,11,14,17-EicosapentaenoicImportantcomponentoffishoils,eg,codliver,mackerel,menhaden,salmonoils.Hexaenoic acids (six double bonds)22:6;4,7,10,13,16,19 3Cervonic(DHA)all-cis-4,

15、7,10,13,16,19-DocosahexaenoicFishoils,phospholipidsinbrain.Unsaturated Fatty Acid23（3）Amino Acid1) Major Elements C 55% H 6-8% O 19-24% N 13-19% S 0-4%The average nitrogen content in proteins is about 16%, and proteins are the major source of N in biological systems. 1g N 6.25g Protein（Kjeldahl meth

16、od）1/16%241）General Formula： R：side chain group H2N C HCOOHR2) Structure of Amino Acids2526 Proline 27lThe R groups, also called side chains, make each AA unique and distinctive. lR groups are different in their size, charge,hydrogen bonding capability and chemical reactivity.lAmino acids are groupe

17、d as (1) acidic; (2) basic; (3)polar, neutral; (4)non-polar, aliphatic; (5)aromatic28|R groups have COOH. |R groups are negatively charged at physiological pH (=7.4). |AAs are soluble in H2O. 29aspartic acid Asp D 2.97glutamic acid Glu E 3.22|R groups have one -NH2（amino, guanidyl, imidazolyl） |R gr

18、oups are positively charged at neutral pH (=7.0). |AAs are highly hydrophilic. 30lysine Lys K 9.74arginine Arg R 10.76histidine His H 7.59|R groups are polar: -OH, -SH, and -NH2. |R groups are highly reactive. |AAs are soluble in H2O, that is, hydrophilic. 32cysteine Cys C 5.07methionine Met M 5.74a

19、sparagine Asn N 5.41glutamine Gln Q 5.65threonine Thr T 5.60serine Ser S 5.68R groups are non-polar, hydrophobic aromatic groups. tryptophane Trp W 5.89tyrosine Tyr Y 5.66phenylalanine Phe F 5.48|R groups are non-polar, hydrophobic aliphatic groups. |R groups are uncharged. |AAs are insoluble in H2O

20、. 34glycine Gly G 5.97alanine Ala A 6.00valine Val V 5.96leucine Leu L 5.98isoleucine Ile I 6.02proline Pro P 6.30364) Uncommon Amino AcidsCreated by modification of common amino acids after translation(protein modification). Cystine-oxidationof2CysteineHydroxyproline-ProlinehydroxylationHyroxylysin

21、e-Lysinehydroxylation375)Essential Amino Acids:38An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism (usually referring to humans), and therefore must be supplied in the diet.OH-6)Physicochemical Properties of Amino AcidAmino Acids

22、are ampholytes R-CH-COOH R-CH-COO R-CH-COO NH3+ NH3+ NH2Positive Ion Zwitterions Negative Ion *pI(Isoelectric pH): the pH at which a particular molecule carries no net electrical charge.OHpHpIH+H+39Phe40A peptide bond is a covalent bond formed between the carboxyl group of one AA and the amino group

23、 of its next AA with the elimination of one H2O molecule.41硒代半胱氨酸（硒代半胱氨酸（Selenocysteine，Sec）吡咯賴氨酸（吡咯賴氨酸（Pyrrolysine，Pyl）421) Elemental composition C，H，O，N，P（9-10%）2) Characteristic components 核苷酸核苷酸Nucleotide核苷核苷nucleoside磷酸磷酸phosphate堿基堿基bases 戊糖戊糖pentose嘧啶嘧啶pyrimidine嘌呤嘌呤purine核糖核糖ribose脫氧核糖脫氧核糖de

24、oxyribose (4) Nucleotide43Nitrogenous BaseslPyrimidine：胞嘧啶：胞嘧啶Cytosine 胸腺嘧啶胸腺嘧啶Thymine 尿嘧啶尿嘧啶UracillPurine：腺嘌呤：腺嘌呤Adenine 鳥嘌呤鳥嘌呤Guanine 44NNHNHNNH2OlPurineNNNHNNH2adenine(A)(6-amino-purine)guanine(G)(2-amino-6-oxy-purine)NNNHN12345678945lPyrimidine cytosine(C)(2-oxy-4-amino-pyrimidine)NNHNH2Ouracil(

25、U)(2,4-oxy-pyrimidine)NHNHOOthymine(T)(5-methyl-uracil)NHNHOOCH3NNH1324564647Absorption of UV：max=260nm481 2 3 4 5 OHOCH2OHOHOHOHOCH2OHOHH1 2 3 4 5 49Nucleoside：C-N Glycosidic Bond N9 of purineN1 of pyrimidineC1 of pentose501 OHOCH2OHOH1NHCOO5HN515 POOOHOHOCH2OHOHNNNH2O5253(5)Other Function of Nucle

26、otideATP，GTP carry chemical energyUTP，CTP group transfer agent cAMP，cGMP second messengersNAD+ ，NADP+，FAD components of cofactors 5455GlycogenesisGlycogen(Gn)Glycogen(Gn+1)Glycogen Synthase562cyclic AMP(cAMP)Acyclic GMP(cGMP)Cell ResponseSecond MessengersReceptorHormone5758Figure 2-17 Molecular Biol

27、ogy of the Cell ( Garland Science 2008)59glycogen、starch ：stored form of energy fuelcellulose : chief constituents of plant cell wallsOligosaccharides: constitute glycoconjugatesGlycosaminoglycan: constitute extracellular matrix60Figure 2-75a Molecular Biology of the Cell ( Garland Science 2008)Glyc

28、ogen116461Figure 2-75b Molecular Biology of the Cell ( Garland Science 2008)62Starchamylopectin63Figure 2-75c Molecular Biology of the Cell ( Garland Science 2008)64Cellulose65 ProteinCarbohydrate Lipid Protein Lipid Microorganism：Peptidoglycan肽聚糖肽聚糖 Lipopolysaccharide脂多糖脂多糖 GlycolipidGlycosyl Phosp

29、hatidyl Inositol(GPI)AnchoredProtein GlycoproteinProteoglycans66Glycoprotein67Unbranched polysaccharide chain compose of repeated disaccharide units.(amino sugar + uronic acid)Be attached to a protein molecule to form a proteoglycan.Glycosaminoglycan68PhospholipidThe two fatty acids within the hydro

30、phobic phosphatidyl-inositol group anchor the protein to the cell membrane.69Lipids compose of Fat and Lipoid.脂肪脂肪 ()： Triglyceride, TG類脂類脂(Lipoid)： 膽固醇膽固醇 (cholesterol, CHOL) 膽固醇酯膽固醇酯 (cholesterol ester, CE) 磷脂磷脂 (phospholipid, PL) 糖脂糖脂(glycolipid)(II) Lipids70 甘油磷脂甘油磷脂(glycerophospholipids)Cholest

31、erol ester FACholestrol Composition of LipidsFAFAFAGlycerol FAFAPiXGlycerol X = choline, water, cholamine, serine, glycerol, inositol, phosphatidylglycerol,et alCH2CHCH2OOOCO(CH2)m CH3CO(CH2)kCH3CO(CH2)nCH3Triglyceride71Sphingolipids Sphingomyelin Glycosphingolipids FASphingosine FA PiXSphingosine F

32、A Glycan Sphingosine 72ClassificationClassificationContentContent DistributionDistributionPhysiologicalPhysiologicalFunctionFunction TriglycerideTriglyceride 9595Adipose tissueAdipose tissue、Blood plasmaBlood plasma1. Store and supply energy.1. Store and supply energy.2. Supply essential fatty acid.

33、2. Supply essential fatty acid.3. Improve intestinal absorption of3. Improve intestinal absorption offat-soluble vitamin s.fat-soluble vitamin s.4. Thermal pad.4. Thermal pad.5. Protection pad,5. Protection pad,6. Component of blood lipoprotein6. Component of blood lipoprotein Glycolipid, Glycolipid

34、, Cholesterol, Cholesterol, Cholesterol ester, Cholesterol ester, Phospholipid Phospholipid5 5BiomembraneBiomembrane, ,Nerve,Nerve,Blood PlasmaBlood Plasma1. Component of 1. Component of biomembranebiomembrane2. Convert to steroid hormones, 2. Convert to steroid hormones, vitamin D, bile acid.vitami

35、n D, bile acid.3. Component of blood lipoprotein3. Component of blood lipoproteinClassification,Content,Distribution and Function of Lipids73|PhosphatidylcholinePolar Head（hydrophilic）Nonpolar Tail（hydrophobic）74Amphiphilic moleculeFigure 2-22 Molecular Biology of the Cell ( Garland Science 2008)Pho

36、spholipid bilayer membrane75Cholesterol Common structure of Sterol: steroid nucleus cyclopentanoperhydrophenanthrene(環戊烷多氫菲環戊烷多氫菲)HHHHHABCD123456789101112131415161776Cholesterol(27carbon atoms)77-谷固醇谷固醇(Sitosterol,29carbon,plant)(Sitosterol,29carbon,plant)麥角固醇麥角固醇(Ergosterol,28carbon,yeast)(Ergoster

37、ol,28carbon,yeast)78Total ContentTotal Content： about about 140g gDistributionDistribution： Widely distributed in all cells of the bodyWidely distributed in all cells of the body About in brain and nervous tissueAbout in brain and nervous tissue Glands (Adrenal gland, Ovary)synthesize sterol Glands

38、(Adrenal gland, Ovary)synthesize sterol hormones have high composition of cholesterolhormones have high composition of cholesterolExistenceExistence：free cholesterolfree cholesterol cholesterol estercholesterol ester79* * Functions FunctionsSignificant constituent of biological membranesSignificant

39、constituent of biological membranes，contribute to membrane mobility controlling .contribute to membrane mobility controlling .Precursorofbileacid,sterolhormonesandvitaminD,etal.80(III) Protein81Peptide unit can rotate freely around C8283 2)Amino Acid Residues, Oligopeptide,Polypeptide, Polypeptide B

40、ackbone、Side chain 3) -NH2 terminal（N-terminal,H-）；）； -COOH terminal（C-terminal,-OH）84*Glutathione (谷胱甘肽谷胱甘肽 , GSH)4)Biologically active peptide：Glutamine Cysteine Glycine85GSH peroxidaseH2O2 2GSH 2H2O GSSG GSH reductaseNADPH+H+ NADP+ 2G-SH G-S-S-G+2H-2HActasareductanttoprotectnucleicacidsandprotein

41、sfromtoxinbydischargingfreeradicalorH2O286NutraSweet87TRH(Thyrotropin Releasing Hormone)GluHisPro*A number of hormones are small peptides.88Super-secondary StructurePrimary Structure of ProteinPrimary StructureSecondary StructureTertiary StructureQuaternary StructureConformation891)Primary Structure

42、 of Protein(1)Definition: the sequence of amino acid residues in peptides, including the position of two Cys residues which create bisulfide bond. (2)Characteristics：the nucleotide sequence in DNA specifies the amino acid sequence of a protein.Primary structure defines the conformation and function

43、of proteins. (3)Major Bond：Peptide Bond，Disulfide Bond90Chain BChain APrimary Structure of Insulin913. Classification of Protein1)Grouped by chemical composition Simple Protein Conjugated Protein2)Grouped by molecular shape Globular Protein Fibrous Protein3)Grouped by function Active Protein Passive

44、 Protein92uMaterial basis of lifeuThe most abundant organic composition in organismsuWorking molecules in organismsuThe substances express genetic information9394 Deoxyribonucleic acid ,DNANucleic Acid Ribonucleic acid,RNA (IV)Nucleic Acidmessenger RNA, mRNAtransfer RNA ,tRNAribosomal RNA, rRNA95Bul

45、ding Blocks of DNA： dAMP、dGMP、dCMP、dTMP Abbr.：A、G、C、TBuiding Blocks of RNA： AMP、GMP、CMP、UMP Abbr.：A、G、C、U961. Primary Structure of DNA Sequence of deoxyribonucleotide residues in polynucleotide chain. lBuilding blocks： AMP，GMP，CMP，TMPphosphodiester bonds5-phosphate group 3-OH group 97 Store genetic

46、information Self-replication Transcript to RNA, and then translate to protein2.Function of DNA:98mRNA、tRNA 、rRNA : participate in protein synthesisOther RNA：snRNA 、ribozyme , et al4.Function of RNA3.Primary Structure of RNASequence of ribonucleotides in polynucleotide chain.99mRNA:Template for Prote

47、in SynthesisProkaryotic mRNAEukaryotic mRNA100tRNA:“Adapter” in Protein SynthesisLinker between mRNA and amino acid101rRNA:Component of ribosome小亞基中的小亞基中的rRNA結構圖結構圖102(V) Compartmentalization of CellsBasic difference between prokaryotes and eukaryotes: Compartmentalization103|Eukaryoticcellsarecharacterizedbycompartmentalizationbyanendomembranesystem,andthepresenceofmembrane-boundorganelles(compartment).|Endomembrane system: A setofthedifferentmembranesthataresuspendedinthecytoplasmwithinaeukaryoticcellanddividethecellintofunctionalandstructuralrelationshipcompartmentsororgane