《生物化学》课程教学资源（文献资料）Lehninger Principles of Biochemistry，5th EDITION，David L. Nelson、Michael M. Cox

1.1 Cellular Foundationsevolved from the samebranchthatgave risetotheAr-moleculespenetrated byproteins.Archaealmembraneschaea; eukaryotes are therefore more closely related tohave a similar architecture, but the lipids are strikinglyarchaea than to bacteria.different from thoseof bacteria (seeFig.10-12).Within the domains of Archaea and Bacteria aresubgroups distinguished by their habitats. In aerobichabitats witha plentiful supply of oxygen,someresidentRibosomes Bacterial ribosomes are smaller thanorganisms deriveenergyfromthetransferofelectronseukaryotic ribosomes, but serve the samefunction-fromfuelmoleculesto oxygen.Otherenvironmentsareprotein synthesis from an RNA message.anaerobic,virtually devoid of oxygen,and microorgan-Nucleoid Contains a single,isms adapted tothese environments obtain energy bysimple,long circular DNAtransferring electrons to nitrate (forming N2),sulfatemolecule(forming H2S),or CO2 (forming CH).Many organismsPili Providethat have evolved in anaerobic environments are oblipointsofgate anaerobes: they die when exposed to oxygen. Oth-adhesion toers are facultative anaerobes, able to live with orsurface ofothercells.without oxygen.Wecan classifyorganisms accordingtohowtheyob-tain the energy and carbon they need for synthesizingFlagellaPropel cellcellularmaterial (as summarized in Fig.1-5).There arethrough itstwo broad categories based on energy sources:pho-surroundings.totrophs (Greek trophe,"nourishment")trap and usesunlight, and chemotrophs derive their energy fronoxidation of a chemical fuel. Some chemotrophs,thelithotrophs, oxidize inorganic fuels--Hs-to s (ele-mental sulfur),sto SO,,NO2toNOs,orFe2+toFe3for example.Organotrophs oxidize a wide array of or-Cell envelopeganic compounds available in theirsurroundings.Pho-Structure variestotrophs and chemotrophs may also be divided intowith type ofthose that can obtain all needed carbon from CO2(au-bacteria.totrophs) and those that require organic nutrients(heterotrophs).Escherichia coli ls the Most-Studied BacteriumBacterial cellssharecertaincommon structuralfeatures,butalsoshowgroup-specific specializations (Fig.1-6).E. coli is a usually harmless inhabitant of the humanintestinal tract.TheE.coli cell is about2μm long andOutermembranePeptidoglycan ayera little less than Iμm in diameter.It has a protectivePeptidoglycan layerInnermembraneoutermembraneandaninnerplasmamembranethatInnermembraneencloses the cytoplasm and the nucleoid.Between theinner and outer membranes is a thin but strong laver ofa polymer (peptidoglycan) that gives the cell its shapeand rigidity.The plasma membrane and the layers out-Gram-positive bacteriaGram-negativebacteriaside it constitute the cell envelope.We should noteNo outer membrane;Outer membrane;here that in archaea, rigidity is conferred by a differentthickerpeptidoglycanlayerpeptidoglycan layertypeof polymer(pseudopeptidoglycan).Theplasmamembranes of bacteria consist of a thin bilayer of lipidFIGURE1-6 Common structural features ofbacterialcells.Because ofdifferences in cell envelope structure, some bacteria (gram-positivebacteria) retain Gram's stain (introduced by Hans Christian Gram in1882), and others (gram-negative bacteria) do not. E. coli is gram-negative.Cyanobacteria are distinguished by their extensive internaArchaeaCyanobacteriaNo outer membrane;membrane system, which is the site of photosynthetic pigments.Al-Gram-negative; tougherpeptidoglycan layer;pseudopeptidoglycanlayerthough the cell envelopes of archaea and gram-positive bacteria lookextensive internaloutsideplasmamembranesimilar under the electron microscope,the structures of the membranemembrane system withlipids and the polysaccharides are distinctly different (see Fig. 10-12).photosynthetic pigments

evolved from the same branch that gave rise to the Ar￾chaea; eukaryotes are therefore more ciosely related to archaea than to bacteria. Within the domains of Archaea and Bacteria are subgroups distinguished by their habitats. In aerobic habitats with a plentiful supply of oxygen, some resident organisms derive energy from the transfer of electrons from fuel molecules to oxygen. Other environments are anaerobic, virtually devoid of oxygen, and microorgan￾isms adapted to these environments obtain energy by transferring electrons to nitrate (forming N2), sulfate (forming H2S), or CO2 (forming CH+). Many organisms that have evolved in anaerobic environments are obLi￾gate anaerobes: they die when exposed to oxygen. Oth￾ers are facultatzue anaerobes, able to live with or without oxygen. We can classify organisms according to how they ob￾tain the energy and carbon they need for q,rrthesizing cellular material (as summarized in Fig. 1-5). There are two broad categories based on energy sources: pho￾totrophs (Greek trophe, "nourishment") trap and use sunlight, and chemotrophs derive their energy from oxidation of a chemicai fuel. Some chemotrophs, the lithotrophs, oxidize inorganic fuels-HS- to Su (ele￾mental sulfur), So to SO;, NOf to NOf , or Fe2* to Fe3*, for example. Organotrophs oxidize a wide array of or￾ganic compounds available in their surroundings. Pho￾totrophs and chemotrophs may also be divided into those that can obtain all needed carbon from CO2 (au￾totrophs) and those that require organic nutrients (heterotrophs). Esrhe ia rolils the Most-Studied Bacterium Bacterial cells share certain corrunon structural features, but also showgroup-speciflc specializations (Fig. f -6). E. coli, is a usually harmless inhabitant of the human intestinal tract. The E. coli, cell is about 2 pm long and a Iittle less than I pr,m in diameter. It has a protective outer membrane and an inner plasma membrane that encloses the cytoplasm and the nucleoid. Between the inner and outer membranes is a thin but strong layer of a pol;'rner (peptidoglycan) that gives the cell its shape and rigidity. The plasma membrane and the layers out￾side it constitute the cell envelope. We should note here that in archaea, rigidity is conferred by a different type of polymer (pseudopeptidoglycan). The plasma membranes of bacteria consist of a thin bilaver of lioid FIGURE 1 -6 Common structural features of bacterial cells. Because of differences in cell envelope structure, some bacteria (gram-positive bacteria) retain Cram's stain (introduced by Hans Christian Cram in 1BB2), and others (gram-negative bacteria) do not. f. coli is gram￾negative. Cyanobacteria are distinguished by their extensive internal membrane system, which is the site of photosynthetic pigments. Al￾though the cell envelopes of archaea and gram-positive bacteria look similar under the electron microscope, the structures of the membrane lipids and the polysaccharides are distinctly different (see Fig. 10-.12). L1 Cellular Foundations 5 molecules penetrated by proteins. Archaeal membranes have a similar architecture, but the lipids are strikingly different from those ofbacteria (see Fig. 10-12). Ribosomes Bacterial ribosomes are smaller than eukaryotic ribosomes, but serve the same functron￾Nucleoid Contains a single, simple, long circular DNA molecule. Pili Provide points of adhesion to surface of * other cells. Cell envelope Structure varies with type of bacteria. Gram-negative bacteria Outer membrane; peptidoglycan layer Gram-positive bacteria No outer membrane; thicker peptidoglycan layer Cyanobacteria Gram-negative; tougher peptidoglycan layer; extensive internal membrane system with photosynthetic pigments Archaea No outer membrane; pseudopeptidoglycan layer outside plasma membrane Flagella " Propel cell through its surroundings

TheFoundations of BiochemistryThe cytoplasm of E.coli contains about 15,000 ri-(metabolites and cofactors),and a variety of inorganicbosomes,various numbers (10tothousands)of copiesions.The nucleoid contains a single, circularmoleculeofofeach of 1,000or so different enzymes,perhaps 1,000DNA, and the cytoplasm (like that of most bacteria)organiccompoundsofmolecularweightlessthan1o00contains one or more smaller, circular segments of DNA(a) Animal cellRibosomes are protein-synthesizingmachinesPeroxisome oxidizes fatty acidsCytoskeleton supports cell, aidsin movement of organellesLysosome degrades intracellulardebrisTransport vesicle shuttles lipidsand proteins between ER, Golgi,andplasmamembraneGolgi complex processes,packages, and targets proteins tootherorganellesorforexportSmooth endoplasmic reticulum(SER)is site of lipid synthesisand drug metabolismNuclear envelope segregatesNucleolus is site of ribosomalchromatin (DNA+protein)RNA synthesisfromcytoplasmNucleus contains theRough endoplasmic reticulumgenes (chromatin)(RER)is site ofmuch proteinsynthesisPlasma membrane separates cellNuclearfrom environment, regulatesenvelopemovement of materials into andRibosomesCytoskeletonoutof cellMitochondrion oxidizes fuels toproduceATPGolgiScomplexChloroplast harvests sunlight,producesATPandcarbohydratesStarch granule temporarily storescarbohydrate products ofphotosynthesisThylakoids are site of light-driven ATP synthesisCell wall provides shape andrigidity: protects cell fromosmotic swellingVacuole degrades and recyclesmacromolecules,storesmetabolitesCell wall of adjacent cellPlasmodesma provides pathbetween two plant cellsGlyoxysome contains enzymes ofthe glyoxylate cycle(b)Plant cellFIGURE1-7 Eukaryotic cell structure.Schematic illustrations of twOStructures labeled in red are unique to either animal or plant cells.major types of eukaryotic cell: (a) a representative animal cell andEukaryoticmicroorganisms (such as protists andfungi)have structures(b)arepresentativeplant cell.Plantcells are usually 10 to100 μm insimilar to those in plant and animal cells, but many also contain spe-diameter-larger than animal cells, which typically range from 5 to 30 μmcialized organellesnot illustrated here

The cytoplasm of -O. coli, contains about 15,000 ri￾bosomes, various numbers (10 to thousands) of copies of each of 1,000 or so different enz5,'rnes, perhaps 1,000 organic compounds of molecular weight less than 1,000 (a) Animal cell Nuclear envelope segregates chromatin (DNA + protein) from cytoplasm (metabolites and cofactors), and a variety of inorganic ions. The nucleoid contains a single, circular molecule of DNA, and the cytoplasm (like that of most bacteria) contains one or more smaller, circular segments of DNA Ribosomes are protein￾synthesizing machines Peroxisome oxidizes fattv acids Cytoskeleton supports cell, aids in movement of organelles me degrades intracellular Ttansport vesicle shuttles lipids and proteins between ER, Golgi, and plasma membrane Golgi complex processes, packages, and targets proteins to other organelles or for export Smooth endoplasmic reticulum (SER) is site of lipid synthesis and drug metabolism Nucleolus is site of ribosomal RNA synthesis Nucleus contains the genes (chromatin) Plasma membrane separates cell from environment, regulates movement of materials into and out of cell Chloroplast harvests sunlight, produces ATP and carbohydrates Thylakoids are site of light￾driven ATP synthesis Cell wall provides shape and rigidity; protects cell from osmotic swelling Rough endoplasmic reticulum (RER) is site of much protein synthesis Mitochondrion oxidizes fuels to produce ATP Nuclear envelope Ribosomes Cytoskeleton Golgi complex Starch granule temporarily stores carbohydrate products of photosynthesis Vacuole degrades and recycles macromolecules, stores metabolites FIGURE 1-7 Eukaryotic cell structure. Schematic illustrations of two major types of eukaryotic cell: (a) a representative animal cell and (b) a representative plant cell. Plant cells are usually .l 0 to .l 00 pm in diameter-largerthan animal cells, which typically rangefrom 5 to 30 pm Plasmodesma provides path between two plant cells Cell wall of adjacent cell Glyoxysome contains enzJrmes of the glyoxylate cycle ft) Plant cell Structures labeled in red are unique to either animal or plant cells. Eukaryotic microorganisms (such as protists and fungi) have structures similar to those in plant and animal cells, but many also contain spe￾cialized orsanelles not illustrated here

1.1 CellularFoundationscalled plasmids. In nature, some plasnids confer resis-of bacteria.Thedistinguishing characteristics of eukary-tance to toxins and antibiotics in the environment. Inotesarethenucleusandavarietyofmembrane-enclosedthe laboratory, these DNA segments are especiallyorganelles with specificfunctions:mitochondria,endo-amenabletoexperimental manipulationandarepowerfulplasmic reticulum, Golgi complexes,peroxisomes,andtools for genetic engineering (see Chapter9)lysosomes.Inaddition tothese,plantcells alsocontainMost bacteria (including E.coli)exist as individualvacuolesand chloroplasts(Fig.1-7).Alsopresentin thecells,but cells of some bacterial species (the myxobac-cytoplasm of many cells are granules or droplets con-teria,for example)show simplesocial behavior,formingtaining stored nutrients such as starchand fat.In a major advance in biochemistry, Albert Claude,many-celledaggregates.Christian deDuve,and GeorgePaladedeveloped meth-odsforseparating organellesfrom thecytosol andfromEukaryotic Cells Havea Varietyof Membranous Organelles,each other-an essential step in investigating theirWhichCanBeIsolatedforStudystructures and functions.In a typical cell fractionationTypicaleukaryotic cells(Fig.1-7)aremuchlarger than(Fig.1-8), cells or tissues in solution are gently dis-bacteria-commonly5to100μmindiameter,withcellrupted by physical shear.This treatment ruptures thevolumes a thousand to a million times larger than thoseplasma membrane but leaves most of the organellesFIGURE1-8 Subcellularfractionation of tissue.A tissue such as liveris first mechanically homogenized tobreak cells and disperse theircontentsin an aqueous buffer.Thesucrose mediumhas an osmoticpressure similarto that in organelles,thus balancingdiffusion of waterinto and out of the organelles,which would swell and burst in a solu-tion of lower osmolarity (see Fig.2-12), (a) The large and small parti-cles in the suspension can be separated by centrifugation at differentspeeds, or (b) particles of different density can be separated by isopyc-nic centrifugation. In isopycnic centrifugation, a centrifuge tube isfilled with a solution, the density of which increases from top to bot-(a)Differentialtom; a solutesuchas sucrose isdissolved at different concentrations tocentrifugationproduce the density gradient. When a mixture of organelles is layeredTissueon top of the densitygradient and the tube is centrifugedat highspeed,homogenizationindividual organelles sedimentuntil their buoyantdensityexactlymatches that in the gradient. Each layer can be collected separately.Low-speed centrifugation(1,000g,10min)(b)Isopyenic(sucrose-density)centrifugationnatantsubjectedtomedium-speedcentrifugation(20.000g,20min)CentrifugationSupernatant subjectedto high-speed★centrifugationTissue(80.000g.1h)homogenateSupernatantsubjected tovery high-speedPelletcentrifugationcontains(150,000g,3h)whole cells,nuclei,Samplecytoskeletons,plasmamembranesPelletSucrosecontainsgradientmitochondria,Supernatantlysosomes,containsperoxisomesLess dense-solublecomponentPelletproteinsFractionationcontainsMore densemicrosomecomponent(fragments of ER),small vesiclesPellet containsribosomes, largeDC765macromolecules3

called plasmids. In nature, some plasmids confer resis￾tance to toxins and antibiotics in the environment. In the laboratory, these DNA segments are especially amenable to experimental marupulation and are powerful tools for genetic engineering (see Chapter 9). Most bacteria (including E. coli,) exist as individual cells, but cells of some bacterial species (the myxobac￾teria, for example) show simple social behavior, forming many-celled aggregates. Eukaryotic Cells Have aVariety of Membranous 0rganelles, Which Can Be lsolated for Study $pical eukaryotic cells (Fig. l-7) are much larger than bacteria-commonly 5 to 100 pm in diameter, with cell volumes a thousand to a million times larger than those (a) Differential centrifugation Tissue homogenization Low-speed centrifu gation (1,000g, 10 min) of bacteria. The distinguishing characteristics of eukary￾otes are the nucleus and a variety of membrane-enclosed organelles with speciflc functions: mitochondria, endo￾plasmic reticulum, Golgi complexes, peroxisomes, and lysosomes. In addition to these, plant cells also contain vacuoles and chloroplasts (Fig. 1-7). Also present in the cytoplasm of many cells are granules or droplets con￾taining stored nutrients such as starch and fat. In a major advance in biochemistry, Albert Claude, Christian de Duve, and George Palade developed meth￾ods for separating organelles from the cytosol and from each other-an essential step in investigating their structures and functions. In a typical cell fractionation (Fig. 1-8), cells or tissues in solution are gently dis￾rupted by physical shear. This treatment ruptures the plasma membrane but leaves most of the organelles FIGURE 1-8 Subcellular fractionation of tissue. A tissue such as liver is first mechanically homogenized to break cells and disperse their contents in an aqueous buffer. The sucrose medium has an osmotic pressure similar to that in organelles, thus balancing diffusion of water into and out of the organelles, which would swell and burst in a solu￾tion of lower osmolarity (see Fig. 2-12). (a) The large and small parti￾cles in the suspension can be separated by centrifugation at different speeds, or (b) particles of different density can be separated by isopyc￾nic centrifugation. In isopycnic centrifugation, a centrifuge tube is filled with a solution, the density of which increases from top to bot￾tom; a solute such as sucrose is dissolved at different concentrations to produce the density gradient. When a mixture of organelles is layered on top of the density gradient and the tube is centrifuged at high speed, individual organellesediment until their buoyant density exactly matches that in the gradient. Each layer can be collected separately. (b) Isopycnic (sucrose-density) centrifugation Less dense component f Centrifugation f contalns mlcrosomes (fragments of ER), small vesicles !i:.: l Pellet contains ribosomes, large macromolecules Pellet | | proteins More dense component 8 7 Sucrose

The Foundations of Biochemistryintact. The homogenate is then centrifuged; organellesskeleton.There are three general types of cytoplasmicsuch as nuclei, mitochondria,and lysosomes differ infilaments--actinfilaments,microtubules.and intermesize and therefore sediment at different rates.diate filaments (Fig. 1-9)differing in width (fromDifferential centrifugation results in a rough frac-about 6to22nm),composition,and specificfunction.tionation of the cytoplasmic contents,which may beAll typesprovide structure and organization to the cyto-furtherpurifiedby isopycnic("samedensity")centrifu-plasm and shapeto the cell. Actin filaments and micro-gation. In this procedure, organelles of different buoy-tubules also help to produce the motion of organelles orant densities (the result of different ratios of lipid andofthewholecell.protein in each type of organelle)are separated by cenEachtypeof cytoskeletal componentis composedtrifugation through a column of solvent with gradedof simpleprotein subunitsthat associatenoncovalentlydensity. By carefully removing material from each retoforn filaments of uniform thickness.Thesefilamentsgion of thegradient and observing itwithamicroscope,are not permanent structures; they undergo constantthebiochemist canestablishthesedimentationpositiondisassemblyintotheirprotein subunits andreassemblyinto filaments. Their locations in cells are not rigidlyof each organelleand obtain purified organelles forfur-ther study.Forexample,these methodswereused to es-fixedbutmay changedramaticallywithmitosis,cytoki-tablish that lysosomes contain degradative enzymes,nesis, amoeboid motion, or changes in cell shape. Themitochondria contain oxidative enzymes,and chloroassembly,disassembly,andlocation of all typesoffila-plasts containphotosyntheticpigments.Theisolation ofments areregulated by otherproteins,whichservetolinkorbundlethefilamentsortomovecytoplasmican organelle enriched in a certain enzyme is often thefirst stepin thepurification of thatenzyme.organelles along the filaments.The picture that emerges from this brief survey ofeukaryotic cell structure is of a cell with a meshwork ofThe CytoplasmIs Organized by the Cytoskeleton and Isstructural fibers and a complex system of membrane-HighlyDynamicenclosed compartments(Fig.1-7.Thefilamentsdisas-Fluorescencemicroscopyreveals several types of proteinsemble and then reassemble elsewhere.Membranousfilaments crisscrossing the eukaryotic cell,formingvesicles bud from one organelleand fuse with another.an interlocking three-dimensional meshwork, the cyto-Organellesmovethroughthecytoplasm alongprotein(a)(b)FIGURE1-9Thethreetypesofcytoskeletal filaments:actinfilaments,from the cell center,are stainedgreen; and chromosomes (in thenumicrotubules,and intermediate filaments.Cellular structures can becleus) are stained blue: (b) A newt lung cell undergoing mitosis. Micro-labeled with an antibody (that recognizes a characteristic protein) co-tubules (green),attached to structures called kinetochores (yellow) onvalentlyattached to a fluorescent compound.The stained structures arethecondensed chromosomes (blue),pull thechromosomes to oppositevisible when the cellisviewed with a fluorescence microscope.(a) En-poles, or centrosomes (magenta), of the cell. Intermediate filaments,dothelial cells from the bovine pulmonary artery. Bundles of actin filamade ofkeratin (red),maintainthe structure of the cellments called "stress fibers"are stained red; microtubules, radiating

intact. The homogenate is then centrifuged; organelles such as nuclei, mitochondria, and lysosomes differ in size and therefore sediment at different rates. Differential centrifugation results in a rough frac￾tionation of the cytoplasmic contents, which may be further purified by isopycnic ("same density") centrifu￾gation. In this procedure, organelles of different buoy￾ant densities (the result of different ratios of lipid and protein in each type of organelle) are separated by cen￾trifugation through a column of solvent with graded density. By carefully removing material from each re￾gion of the gradient and observing it with a microscope, the biochemist can establish the sedimentation position of each organelle and obtain purifled organelles for fur￾ther study. For example, these methods were used to es￾tablish that lysosomes contain degradative enzymes, mitochondria contain oxidative enzyrnes, and chloro￾plasts contain photosynthetic pigments. The isolation of an organelle enriched in a certain enzyrne is often the first step in the purification of that enzyme. The (ytoplasm ls Organized by the (ytoskeleton and ls Highly Dynamic Fluorescence microscopy reveals several types of protein filaments crisscrossing the eukaryotic cell, forming an interlocking three-dimensional meshwork, the cyto￾FIGURE 1 - 9 The three types of cytoskeletal fitaments: actin fitaments, microtubules, and intermediate filaments. Cellular structures can be labeled with an antibody (that recognizes acharacteristic protein) co￾valently attached to a fluorescent compound. The stained structures are visible when the cell is viewed with a fluorescence microscope. (a) En￾dothelial cells from the bovine pulmonary artery. Bundles of actin fila￾ments called "stress fibers" are stained red; microtubules, radiating skeleton. There are three general types of cytoplasmic filaments-actin fi.laments. microtubules. and interme￾diate filaments (Fig. l-9)-differing in width (from about 6 to 22 run), composition, and specific function. All types provide structure and organization to the cyto￾plasm and shape to the cell. Actin fllaments and micro￾tubules also help to produce the motion of organelles or of the whole cell. Each type of cytoskeletal component is composed of simple protein subunits that associate noncovalently to form fllaments of uniform thickness. These filaments are not permanent structures; they undergo constant disassembly into their protein subunits and reassembly into filaments. Their locations in cells are not rigidly fixed but may change dramatically with mitosis, cytoki￾nesis, amoeboid motion, or changes in cell shape. The assembly, disassembly, and location of all types of flla￾ments are regulated by other proteins, which serve to Iink or bundle the filaments or to move cltoplasmic organelles along the filaments. The picture that emerges from this brief survey of eukaryotic cell structure is of a cell with a meshwork of structural flbers and a complex system of membrane￾enclosed compartments (Fig. 1-7). The fllaments disas￾semble and then reassemble elsewhere. Membranous vesicles bud from one organelle and fuse with another. Organelles move through the cytoplasm along protein from the cell center, are stained green; and chromosomes (in the nu￾cleus) are stained blue. (b) A newt lung cell undergoing mitosis. Micro￾tubules (green), attached to structures called kinetochores (yellow) on the condensed chromosomes (blue), pull the chromosomes to opposite poles, or centrosomes (magenta), of the cell. Intermediate filaments, made of keratin (red), maintain the structure of the cell

1.1CellularFoundationsfilaments,theirmotion powered byenergy-dependentAlthough complex, this organization of the cyto-motor proteins.The endomembrane system segre-plasmisfarfromrandom.Themotionandpositioning ofgates specific metabolic processes and provides sur-organelles and cytoskeletal elements are under tightfaces on which certain enzyne-catalyzed reactionsregulation, and at certain stages in its life, a eukaryoticoccur.Exocytosis and endocytosis,mechanisms ofcell undergoes dramatic,finely orchestrated reorganiza-transport (out of and into cells, respectively) that in-tions, suchas theevents of mitosis.Theinteractions be-volve menbrane fusion and fission, provide paths be-tween the cytoskeleton and organelles are noncovalent,tweenthecytoplasmandsurroundingmedium,allowingreversible, and subject to regulation in response tofor secretion of substances produced in the cell andvarious intracellular and extracellular signals.uptake ofextracellularmaterials.Cells Build SupramolecularStructures(a) Some of the amino acids of proteinsMacromolecules and their monomeric subunits differgreatly in size (Fig. 1-10). An alanine molecule is lessCOOCOO"COOthan 0.5nmlong.Amoleculeof hemoglobin,the oxygen-H.N-C-HHN.-HH.N--C-Hcarrying protein of erythrocytes (red blood cells), con-CHCH,OHCH2sists of nearly 600 arnino acid subunits in four long chains,folded intoglobularshapesandassociatedinastructureCOOAlanineSerine5.5 nm in diameter. In turn, proteins are much smallerAspartatethan ribosomes (about20 nm in diameter),which areinturn much smaller than organelles such as mitochondria,COO'cOOCOOHaNH,N--HHFIGURE1-10 Theorganic compoundsfromwhichmostcellularma-H,N-HCH2CH2terials are constructed:the ABCs of biochemistry.Shown here areNHCH2C(a) six of the 20 amino acids from which all proteins are built (the sideCHSHchains are shaded pink); (b) the five nitrogenous bases, two five-HC.NHcarbon sugars, and phosphate ion from which all nucleic acids areCysteineOHbuilt;(c)five components of membrane lipids;and (d)D-glucose,theHistidinesimple sugar from which most carbohydrates are derived. Note thatTyrosinephosphate is a component of both nucleic acids and membrane lipids.(b)The components ofnucleic acids(c)Some components of lipids00=COO-CH,OHCOO-NH2CHaCH2CHOHCHHNHNCHCHCH2CH2CH,OHOHCHCHGlycerolCH2CH2.OZEZENECH2CH,UracilCHaThymineCytosineCH2CH2CH.-N-CH,CH2OHCH2CH2NH2OCHSCHaCHCholine0HCHCHHOOHHCH-CH,0H,NHHCH2CH2PhosphateAdenineGuanine(d) Theparent sugarCH,CHNitrogenous basesCH2CH,HOCH20CH2CH2CH,OHHHOCH,RCHaHCH2HOHHOHCHsCH2OHOHOHHOOHPalmitateOHHCH2OHHa-D-RiboseCH2-Deoxy-α-D-riboseFive-carbon sugarsOleateQ-D-Glucose

. ?oo￾H3N-C-H CHs Alanine coo- *l H3N_?-H cH2oH Serine coo *l H3N-?-H 9H, i-NS ll .cH nc-iifr Histidine . ?oo- H3N-?-H ?", coo￾Aspartate coo- *l H3N-?-H CHO l- SH Cysteine . ?oo- H3N-?-H OH Tyrosine (b) The componente of nucleic acids fllaments, their motion powered by energy-dependent motor proteins. The endomembrane system segre￾gates specific metabolic processes and provides sur￾faces on which certain enz;nne-catalyzed reactions occur. Exocytosis and endocytosis, mechanisms of transport (out of and into cells, respectively) that in￾volve membrane fusion and flssion, provide paths be￾tween the cytoplasm and surrounding medium, allowing for secretion of substances produced in the cell and uptake of extracellular materials. (a) Some of the amino acids of proteins 1.1 (ellular Foundations I L-l Although complex, this organization of the cyto￾plasm is far from random. The motion and positioning of organelles and cytoskeletal elements are under tight regulation, and at certain stages in its life, a eukaryotic cell undergoes dramatic, finely orchestrated rcotganiza￾tions, such as the events of mitosis. The interactions be￾tween the cytoskeleton and organelles are noncovalent, reversible, and subject to regulation in response to various intracellular and extracellular signals. (ells Build Supramoletular Structures Macromolecules and their monomeric subunits differ greatly in size (FiS. f-f0). An alanine molecule is less than 0.5 nm long. A molecrile of hemoglobin, the oxygen￾carrying protein of erythrocytes (red blood cells), con￾sists of nearly 600 amino acid subunits in four long chains, folded into globular shapes and associated in a structure 5.5 nm in diameter. In turn, proteins are much smaller than ribosomes (about 20 nm in diameter), which are in turn much smaller than organelles such as mitochondria, FIGURE 1-10 The organic compounds from which most cellular ma￾terials are constructed: the ABCs of biochemistry. Shown here are (a) six of the 20 amino acids from which all proteins are built (the side chains are shaded pink); (b) the five nitrogenous bases, two five￾carbon sugars, and phosphate ion from which all nucleic acids are built; (c) five components of membrane lipids; and (d) o-glucose, the simple sugar from which most carbohydrates are derived. Note that phosphate is a component of both nucleic acids and membrane lipids. (c) Some components of lipids coo￾I cHo I cHo j - CH" t￾cHo I CHo I CHO t￾CH, t￾cHo I CH, t￾cHo t- CHo t￾cHo t- CHo t- CHo l- CHt Palmitate ?H,OH CHOH I cH2oH Glycerol j', cHr-11- at2cH2oH CHs o- Choline I HO-P-OH ll o Phosphate coo CH, t￾cHo t￾CHo t- CHo t- CHo I cHo t￾CH, t￾CH tl CH I CHo I cHo I cH" t￾CHO t￾cHo t￾CHO I cH, I CHg Oleate (d) The parent sugar H HO HOH a-p-Glucose HN-c-cH ttl OzC'.*,'CH H Uracil o 111J-c.-a-CH, rtl ozc:*-cH H Thymine NH" t￾NAcs til ozc'-*,.cH H Cytosine o ir Nitrogenous bases a-p-Ribose 2-Deoxy-a-o-ribose Five-carbon sugars