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milligrams per day of Fe, Cu, and Zn, even less of the others. The elemental requirements for plants and microorganisms are similar to those shown here; the ways in which they acquire these elements vary. 8885d_c01_013 1/15/04 3:28 PM Page 13 mac76 mac76:385_reb: form the strongest bonds. The trace elements (Fig. 1–12)... |
14) and an average length of 0.154 nm. There is free rotation around each single bond, unless very large or highly charged groups are attached to both carbon atoms, in which case rotation may be restricted. A double bond is shorter (about 0.134 nm) and rigid and allows little rotation about its axis. Covalently linked ... |
represent “any substituent.” It may be as simple as a hydrogen atom, but typically it is a carbon-containing moiety. When two or more substituents are shown in a molecule, we designate them R1, R2, and so forth. Ester R1 C O R2 Phosphoanhydride R1 O P O O O Anhydride R1 C O C R2 Mixed anhydride R C O (two carboxylic a... |
OOP A OH PO C H O H phosphoryl of the cell or between compartments in eukaryotic cells. The universal occurrence of the same set of compounds in living cells is a manifestation of the universality of metabolic design, reflecting the evolutionary conservation of metabolic pathways that developed in the earliest cells. ... |
The molecular mass, m, is expressed in daltons (abbreviated Da). One dalton is equivalent to one-twelfth the mass of carbon-12; a kilodalton (kDa) is 1,000 daltons; a megadalton (MDa) is 1 million daltons. Consider, for example, a molecule with a mass 1,000 times that of water. We can say of this molecule either Mr 18... |
. Shorter polymers of sugars (oligosaccharides) attached to proteins or lipids at the cell surface serve as specific cellular signals. The lipids, greasy or oily hydrocarbon derivatives, serve as structural components of membranes, energy-rich fuel stores, pigments, and intracellular signals. In proteins, nucleotides, ... |
represents a bond in which the atom at the wide end projects out of the plane of the paper, toward the reader; a dashed wedge (^) represents a bond extending behind the plane of the paper. (b) Ball-and-stick model, showing relative bond lengths and the bond angles. (c) Space-filling model, in which each atom is shown ... |
, or cistrans, isomers; they differ in the arrangement of their substituent groups with respect to the nonrotating double bond (Latin cis, “on this side”—groups on the same side of the double bond; trans, “across”—groups on opposite sides). Maleic acid is the cis isomer and fumaric acid the trans isomer; each is a well... |
A C B A C Y X X Chiral molecule: Rotated molecule cannot be superimposed on its mirror image B A C X B (a) Y Mirror image of original molecule Original molecule X A C B A C X X X Achiral molecule: Rotated molecule can be superimposed on its mirror image B A C X B (b) X FIGURE 1–19 Molecular asymmetry: chiral and achir... |
There are four different 2,3-disubstituted butanes (n 2 asymmetric carbons, hence 2n 4 stereoisomers). Each is shown in a box as a perspective formula and a ball-and-stick model, which has been rotated to allow the reader to view all the groups. Some pairs of stereoisomers are mirror images of each other, or enantiome... |
omeric forms (designated D and L), alanine in proteins exists exclusively in one form (the L isomer; see Chapter 3). HOOC1 2 C 3 C C4 OOH HOOC1 C4 O OH 2 C 3 C H OH OH H HO H H OH (2R,3R)-Tartaric acid (dextrorotatory) (2S,3S)-Tartaric acid (levorotatory) FIGURE 1 Pasteur separated crystals of two stereoisomers of tart... |
staggered, which is more stable than all others and thus predominates, and the eclipsed, which is least stable. We cannot isolate either of these conformational forms, because 8885d_c01_020 1/15/04 3:29 PM Page 20 mac76 mac76:385_reb: 20 Chapter 1 The Foundations of Biochemistry ) 12 8 4 0 12.1 kJ/mol 0 60 120 180 240... |
above, is the most useful for some biomolecules.) In contrast, when a compound with an asymmetric carbon atom is chemically synthesized in the laboratory, the reaction usually pro- FIGURE 1–22 Complementary fit between a macromolecule and a small molecule. A segment of RNA from the regulatory region TAR of the human i... |
omers distinguishable by smell and taste in humans. (a) Two stereoisomers of carvone: (R)-carvone (isolated from spearmint oil) has the characteristic fragrance of spearmint; (S)-carvone (from caraway seed oil) smells like caraway. (b) Aspartame, the artificial sweetener sold under the trade name NutraSweet, is easily ... |
or fuels to the many energyconsuming processes they must carry out. One goal of biochemistry is to understand, in quantitative and chemical terms, the means by which energy is extracted, channeled, and consumed in living cells. We can consider cellular energy conversions—like all other energy conversions—in the contex... |
Organisms Transform Energy and Matter from Their Surroundings For chemical reactions occurring in solution, we can define a system as all the reactants and products present, the solvent that contains them, and the immediate atmosphere—in short, everything within a defined region of space. The system and its surroundin... |
simpler than the initial fuel molecules: CO2, NH3, 2 H2O, HPO4 (d) Decreased randomness (entropy) in the system Simple compounds polymerize to form information-rich macromolecules: DNA, RNA, proteins (e) FIGURE 1–24 Some energy interconversion in living organisms. During metabolic energy transductions, the randomness ... |
the universe is continually increasing. To bring about the synthesis of macromolecules from their monomeric units, free energy must be supplied to the system (in this case, the cell). The randomness or disorder of the components of a chemical system is expressed as entropy, S (Box 1–3). Any change in randomness of the... |
. 1–15). Here, each P represents a phosphoryl group: G1 is positive (endergonic) Amino acids 888n polymer O PO P 888n O P P G2 is negative (exergonic) When these reactions are coupled, the sum of G1 and G2 is negative—the overall process is exergonic. By this coupling strategy, cells are able to synthesize and maintain... |
the temperature of the surroundings (the kitchen) by an infinitesimally small amount until complete equilibrium is attained. At this point all parts of the teakettle and the kitchen are at precisely the same temperature. The free energy that was once concentrated in the teakettle of hot water at 100 C, potentially cap... |
random arrangement of 125 letters of the English alphabet: certain amount of work. The amount of energy available to do work is the free-energy change, G; this is always somewhat less than the theoretical amount of energy released, because some energy is dissipated as the heat of friction. The greater the elevation of ... |
immensely rich in information and thus entropy-poor. 1.3 Physical Foundations 25 (a) Mechanical example ∆G > 0 Work done raising object ∆G < 0 Loss of potential energy of position Endergonic Exergonic (b) Chemical example Reaction 2: ATP → ADP Pi Reaction 3: Glucose ATP → glucose 6-phosphate ADP Reaction 1: → Glucose ... |
of glucose to glucose 6-phosphate, the first step in the pathway for oxidation of glucose. The simplest way to produce glucose 6-phosphate would be: Reaction 1: Glucose Pi On glucose 6-phosphate (endergonic; G1 is positive) 2. (Pi is an abbreviation for inorganic phosphate, HPO4 Don’t be concerned about the structure ... |
and so on, when the system has reached equilibrium. A large value of Keq means the reaction tends to proceed until the reactants have been almost completely converted into the products. Gibbs showed that G for any chemical reaction is a function of the standard free-energy change, G— a constant that is characteristic ... |
rate of specific chemical reactions without being consumed in the process. The path from reactant(s) to product(s) almost invariably involves an energy barrier, called the activation barrier (Fig. 1–27), that must be surmounted for any reaction to proceed. The breaking of existing bonds and formation of new ones gener... |
simple end products in order to extract chemical energy and convert it into a form useful to the cell; together these degradative, free-energy-yielding reactions are designated catabolism. Other pathways start with small precursor molecules and convert them to progressively larger and more complex molecules, including... |
, fat, protein, and nucleic acid molecules and their simpler subunits, but they do so in the precise proportions required by 8885d_c01_01-46 10/27/03 7:48 AM Page 28 mac76 mac76:385_reb: 28 Chapter 1 The Foundations of Biochemistry the cell under any given circumstance. For example, during rapid cell growth the precurs... |
is a huge job that has only just begun. SUMMARY 1.3 Physical Foundations ■ Living cells are open systems, exchanging matter and energy with their surroundings, extracting and channeling energy to maintain themselves in a dynamic steady state distant from equilibrium. Energy is obtained from sunlight or fuels by conver... |
/30/03 6:34 AM Page 29 mac76 mac76:385_reb: 1.4 Genetic Foundations 29 molecule of DNA can be many centimeters long). A human sperm or egg, carrying the accumulated hereditary information of billions of years of evolution, transmits this inheritance in the form of DNA molecules, in which the linear sequence of covalent... |
assured by the information present in the other strand, which acts as a template for repair of the damage. The Linear Sequence in DNA Encodes Proteins with Three-Dimensional Structures (a) (b) FIGURE 1–29 Two ancient scripts. (a) The Prism of Sennacherib, inscribed in about 700 B.C.E., describes in characters of the A... |
10/27/03 7:48 AM Page 30 mac76 mac76:385_reb: 30 Chapter 1 The Foundations of Biochemistry shape, determined by its amino acid sequence and stabilized primarily by noncovalent interactions. Although the final shape of the folded protein is dictated by its amino acid sequence, the folding process is aided by “molecular... |
dimensional Transcription of DNA sequence into RNA sequence RNA 1 RNA 2 RNA 3 Translation (on the ribosome) of RNA sequence into protein sequence and folding of protein into native conformation Protein 1 Protein 2 Protein 3 Formation of supramolecular complex FIGURE 1–31 DNA to RNA to protein. Linear sequences of deoxy... |
enitor and were derived from it by a series of small changes (mutations), each of which conferred a selective advantage to some organism in some ecological niche. Changes in the Hereditary Instructions Allow Evolution Despite the near-perfect fidelity of genetic replication, infrequent, unrepaired mistakes in the DNA r... |
what Darwin meant by “survival of the fittest under selective pressure.” Occasionally, a whole gene is duplicated. The second copy is superfluous, and mutations in this gene will not be deleterious; it becomes a means by which the cell may evolve: by producing a new gene with a new function while retaining the origina... |
in turn assembled spontaneously to form membranes and catalysts (enzymes), which came together to become precursors of the earliest cells. Oparin’s views remained speculative for many years and appeared untestable—until a surprising experiment was conducted using simple equipment on a desktop. Chemical Evolution Can B... |
aseous contents of the system to electrical sparks, products were collected by condensation. Biomolecules such as amino acids were among the products. tion suggests that RNA or a similar molecule may have been the first gene and the first catalyst. According to this scenario (Fig. 1–34), one of the earliest stages of b... |
nucleic acids within these lipid enclosures favored the molecular interactions required in self-replication. Creation of prebiotic soup, including nucleotides, from components of Earth’s primitive atmosphere Production of short RNA molecules with random sequences Selective replication of self-duplicating catalytic RNA... |
. A very significant evolutionary event was the development of pigments capable of capturing the energy of light from the sun, which could be used to reduce, or “fix,” CO2 to form more complex, organic compounds. The original electron donor for these photosynthetic processes was probably H2S, yielding elemental sulfur ... |
Appearance of endosymbionts (mitochondria, plastids) 1,500 Appearance of protists, the first eukaryotes 2,000 2,500 Appearance of aerobic bacteria Development of O2-rich atmosphere 3,000 Appearance of photosynthetic O2-producing cyanobacteria 3,500 Appearance of photosynthetic sulfur bacteria Appearance of methanogens... |
to the evolution of ever more complex and highly differentiated organisms, in which some cells carried out the sensory functions, others the digestive, photosynthetic, or reproductive functions, and so forth. Many modern multicellular organisms contain hundreds of different cell types, each specialized for some functi... |
m) DNA with nonhistone protein; genome in nucleoid, not surrounded by membrane Fission or budding; no mitosis Membrane-bounded organelles Absent Generally large (5–100 m) DNA complexed with histone and nonhistone proteins in chromosomes; chromosomes in nucleus with membranous envelope Mitosis, including mitotic spindl... |
the fruit fly), mice, rats, and Homo sapiens (you) (Table 1–4). More sequences are being added to this list regularly. With such sequences in hand, detailed and quantitative comparisons among species can provide deep insight into the evolutionary process. Thus far, the molecular phylogeny derived from gene sequences is... |
the proteins they encode are homologs. If two homologous genes occur in the same species, they are said to be paralogous and their protein products are paralogs. Paralogous genes are presumed to have been derived by gene duplication followed by gradual changes in the sequences of both copies (Fig. 1–37). Typically, pa... |
and so on. Comparisons of the whole genomes of species in each phylum may lead to the identification of genes critical to fundamental evolutionary changes in body plan and development. 8885d_c01_038 1/15/04 3:30 PM Page 38 mac76 mac76:385_reb: 38 Chapter 1 The Foundations of Biochemistry Species A Gene 1 Function 1 3 M... |
(DNA synthesis, protein synthesis, generation of ATP, and so forth) in which they function and thus find what fraction of the genome is allocated to each of a cell’s activities. The largest category of genes in E. coli, A. thaliana, and H. sapiens consists of genes of as yet unknown function, which make up more than 4... |
“medical history” may be replaced by a “medical forecast.” ■ 8885d_c01_039 1/15/04 3:30 PM Page 39 mac76 mac76:385_reb: SUMMARY 1.5 Evolutionary Foundations ■ Occasional inheritable mutations yield an organism that is better suited for survival in an ecological niche and progeny that are preferentially selected. This ... |
Life, Oxford University Press, Oxford. Judson, H.F. (1996) The Eighth Day of Creation: The Makers of the Revolution in Biology, expanded edn. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. A highly readable and authoritative account of the rise of biochemistry and molecular biology in the twentieth centu... |
New York. 8885d_c01_01-46 10/27/03 7:48 AM Page 40 mac76 mac76:385_reb: 40 Chapter 1 The Foundations of Biochemistry Like the book by Alberts and coauthors, a superb text useful for this and later chapters. Pierce, B. (2002) Genetics: A Conceptual Approach, W. H. Freeman and Company, New York. Purves, W.K., Sadava, D.... |
er, S.E., Holt, R.A., Evans, C.A., Gocayne, J.D., Amanatides, P.G., Scherer, S.E., Li, P.W., Hoskins, R.A., Galle, R.F., et al. (2000) The genome sequence of Drosophila melanogaster. Science 287, 2185–2195. Determination of the entire genome sequence of the fruit fly. Venter, J.C., Adams, M.D., Myers, E.W., Li, P.W., M... |
the light of modern endosymbiotic anaerobic organisms. Gesteland, R.F. & Atkins, J.F. (eds) (1993) The RNA World, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY. A collection of stimulating reviews on a wide range of topics related to the RNA world scenario. Arabidopsis Genome Initiative. (2000) Analysis ... |
Archaeal-eubacterial mergers in the origin of Eukarya: phylogenetic classification of life. Proc. Natl. Acad. Sci. USA 93, 1071–1076. 8885d_c01_041 1/16/04 12:35 PM Page 41 mac76 mac76:385_reb: The arguments for dividing all living creatures into five kingdoms: Monera, Protoctista, Fungi, Animalia, Plantae. (Compare t... |
diameter of 1.5 m.) (d) Glucose is the major energy-yielding nutrient for most cells. Assuming a cellular concentration of 1 mM, calculate how many molecules of glucose would be present in our hypothetical (and spherical) eukaryotic cell. (Avogadro’s number, the number of molecules in 1 mol of a nonionized substance, ... |
in DNA consists of a linear sequence of coding units, known as codons. Each codon is a specific sequence of three deoxyribonucleotides (three deoxyribonucleotide pairs in double-stranded DNA), and each codon codes for a single amino acid unit in a protein. The molecular weight of an E. coli DNA molecule is about 3.1 1... |
axonal tip in the toes? In studying a particular 9. Separating Biomolecules biomolecule (a protein, nucleic acid, carbohydrate, or lipid) in the laboratory, the biochemist first needs to separate it from other biomolecules in the sample—that is, to purify it. Specific purification techniques are described later in the... |
? 7. Identification of Functional Groups Figures 1–15 and 1–16 show some common functional groups of biomolecules. Because the properties and biological activities of biomolecules are largely determined by their functional groups, it is important to be able to identify them. In each of the compounds below, circle and i... |
mac76 mac76:385_reb: (b) Phosphatidylcholine, a component of many mem- Chapter 1 Problems 43 branes: HO H CH2 C O C NH2 H2C COO C H2 C H2 S CH3 (c) Methionine enkephalin, the brain’s own opiate: CH3 CH3 N CH2 CH2 O CH3 O P O O CH2 H C O H C H C (CH2 )7 CH 3 (CH2)7 C O CH2 O C O (CH2)14 CH3 13. Determination of the Str... |
Acids, Peptides, and Proteins 75 The Three-Dimensional Structure of Proteins 116 Protein Function 157 Enzymes 190 Carbohydrates and Glycobiology 238 2 Water 3 4 5 6 7 8 Nucleotides and Nucleic Acids 273 9 DNA-Based Information Technologies 306 10 11 Biological Membranes and Transport 369 12 Biosignaling 421 Lipids 343... |
I. The chapters of Part I are devoted to the structure and function of the major classes of cellular constituents: water (Chapter 2), amino acids and proteins (Chapters 3 through 6), sugars and polysaccharides (Chapter 7), nucleotides and nucleic acids (Chapter 8), fatty acids and lipids (Chapter 10), and, finally, me... |
of polysaccharides, nucleic acids, and lipids can be understood as a direct manifestation of their chemical structure, with their characteristic monomeric subunits linked in precise functional polymers. Sugars linked together become energy stores, structural fibers, and points of specific molecular recognition; nucleo... |
47 mac76 mac76:385_reb: O – O C CH H chapter 2 WATER 2.1 Weak Interactions in Aqueous Systems 47 Ionization of Water, Weak Acids, and 2.2 Weak Bases 60 2.3 Buffering against pH Changes in Biological Systems 65 2.4 Water as a Reactant 69 2.5 The Fitness of the Aqueous Environment for Living Organisms 70 I believe that ... |
interfere with water-water interactions but are unable to form water-solute interactions— consequently, nonpolar molecules are poorly soluble in water. In aqueous solutions, nonpolar molecules tend to cluster together. Hydrogen bonds and ionic, hydrophobic (Greek, “water-fearing”), and van der Waals interactions are i... |
orbitals of carbon (see Fig. 1–14). These orbitals describe a rough tetrahedron, with a hydrogen atom at each of two corners and unshared electron pairs at the other two corners (Fig. 2–1a). The HOOOH bond angle is 104.5, slightly less than the 109.5 of a perfect tetrahedron because of crowding by the nonbonding orbit... |
-74 7/25/03 10:05 AM Page 49 mac76 mac76:385_reb: Chapter 2 Water 49 water or 348 kJ/mol for a covalent COC bond. The hydrogen bond is about 10% covalent, due to overlaps in the bonding orbitals, and about 90% electrostatic. At room temperature, the thermal energy of an aqueous solution (the kinetic energy of motion of... |
.0 kJ/mol During melting or evaporation, the entropy of the aqueous system increases as more highly ordered arrays of water molecules relax into the less orderly hydrogenbonded arrays in liquid water or the wholly disordered gaseous state. At room temperature, both the melting of ice and the evaporation of water occur ... |
relatively high boiling point of 117 C, whereas butane (CH3(CH2)2CH3) has a boiling point of only 0.5 C. Butanol has a polar hydroxyl group and thus can form intermolecular hydrogen bonds. Uncharged but polar biomolecules such as sugars dissolve readily in water because of the stabilizing effect of hydrogen bonds betw... |
poor solvents for polar biomolecules but easily dissolve those that are hydrophobic—nonpolar molecules such as lipids and waxes. Water dissolves salts such as NaCl by hydrating and stabilizing the Na and Cl ions, weakening the electrostatic interactions between them and thus counteracting their tendency to associate i... |
dimensionless) is 78.5, and for the very nonpolar solvent benzene, is 4.6. Thus, ionic interactions are much stronger in less polar environments. The dependence on r2 is such that ionic attractions or repulsions operate only over short distances—in the range of 10 to 40 nm (depending on the electrolyte concentration) ... |
) that facilitate the transport of O2. Carbon dioxide forms carbonic acid (H2CO3) in aqueous solution and is transported as the (bicarbonate) ion, either free—bicarbonate is HCO3 very soluble in water (~100 g/L at 25 C)—or bound to hemoglobin. Two other gases, NH3 and H2S, also have biological roles in some organisms; ... |
Table 2–2). When an amphipathic compound is mixed with Gas Nitrogen Oxygen Carbon dioxide Ammonia Hydrogen sulfide Structure* NmN OPO OPCPO Polarity Nonpolar Nonpolar Nonpolar Polar Polar Solubility in water (g/L)† 0.018 (40 °C) 0.035 (50 °C) 0.97 (45 °C) 900 (10 °C) 1,860 (40 °C) *The arrows represent electric dipoles... |
nonpolar moieties. Rather, it results from the system’s achieving greatest thermodynamic stability by minimizing the number of ordered water molecules required to surround hydrophobic portions of the solute molecules. Many biomolecules are amphipathic; proteins, pigments, certain vitamins, and the sterols and phosphol... |
transient electric dipole, which induces a transient, opposite electric dipole in the nearby atom. The two dipoles weakly attract each other, bringing the two nuclei closer. These weak attractions are called van der Waals interactions. As the two nuclei draw closer together, their electron clouds begin to repel each o... |
radii describe the space-filling dimensions of atoms. When two atoms are joined covalently, the atomic radii at the point of bonding are less than the van der Waals radii, because the joined atoms are pulled together by the shared electron pair. The distance between nuclei in a van der Waals interaction or a covalent ... |
with binding energy. The dissociation of two biomolecules (such as an enzyme and its bound substrate) associated noncovalently Chapter 2 Water 55 through multiple weak interactions requires all these interactions to be disrupted at the same time. Because the interactions fluctuate randomly, such simultaneous disruptio... |
to be part of the crystal structure; the same is true for water in crystals of RNA or DNA. These bound water molecules, which can also be detected in aqueous solutions by nuclear magnetic resonance, have distinctly different properties from those of the “bulk” water of the solvent. They are, for example, not osmotical... |
point), and osmotic pressure. These are called colligative (“tied together”) properties, because the effect of solutes on all four properties has the same basis: the concentration of water is lower in solutions than in pure water. The effect of solute concentration on the colligative properties of water is independent... |
the absolute temperature. The term ic is the osmolarity of the solution, the product of the solute’s molar concentration c and the van’t Hoff factor i, which is a measure of the extent to which the solute dissociates into two or more ionic species. In dilute NaCl solutions, the solute completely 8885d_c02_47-74 7/25/0... |
passage of water. Solutions of equal osmolarity are said to be isotonic. Surrounded by an isotonic solution, a cell neither gains nor loses water (Fig. 2–13). In a hypertonic solution, one with higher Chapter 2 Water 57 osmolarity than the cytosol, the cell shrinks as water flows out. In a hypotonic solution, with low... |
the solution in the tube to the level of that in the beaker. This force is proportional to the height, h, of the column in (b). 8885d_c02_47-74 7/25/03 10:05 AM Page 58 mac76 mac76:385_reb: 58 Part I Structure and Catalysis Extracellular solutes Intracellular solutes (a) Cell in isotonic solution; no net water movemen... |
osomes, for example, are bounded by semipermeable membranes. In isolating these organelles from broken cells, biochemists must perform the fractionations in isotonic solutions (see Fig. 1–8). Buffers used in cellular fractionations commonly contain sufficient concentrations (about 0.2 M) of sucrose or some other inert ... |
The highly specialized leaves of the Venus flytrap (Dionaea muscipula) rapidly fold together in response to a light touch by an unsuspecting insect, entrapping the insect for later digestion. Attracted by nectar on the leaf surface, the insect touches three mechanically sensitive hairs, triggering the traplike closing... |
the relevant equilibrium constants for each ionization reaction. We therefore turn now to a brief discussion of the ionization of water and of weak acids and bases dissolved in water. Pure Water Is Slightly Ionized Water molecules have a slight tendency to undergo reversible ionization to yield a hydrogen ion (a proto... |
the remarkably ions compared with other monovalent high ionic mobility of H. or K cations such as Na expressing the extent of ionization of water in quantitative terms. A brief review of some properties of reversible chemical reactions shows how this can be done. The position of equilibrium of any chemical reaction is... |
of H and OH, namely, 1 107 M. Accordingly, we can substitute 55.5 M in the equilibrium constant expression (Eqn 2–3) to yield ] OH ][, Keq.5 5 M [H 5 which, on rearranging, becomes (55.5 M)(Keq) [H][OH] Kw (2–4) where Kw designates the product (55.5 M)(Keq), the ion product of water at 25 °C. The value for Keq, determ... |
: 1 log (1.0 107) pH log 107 1.0 log 1.0 log 107 0 7 7 TABLE 2–6 The pH Scale [H] (M) 100 (1) 101 102 103 104 105 106 107 108 109 1010 1011 1012 1013 1014 pH 10 11 12 13 14 [OH] (M) pOH* 1014 1013 1012 1011 1010 109 108 107 106 105 104 103 102 101 100 (1) 14 13 12 11 10 The expression pOH is sometimes used to describe ... |
one solution has ten times the H concentration of the other, but it does not tell us the absolute magnitude of the difference. Figure 2–15 gives the pH of some common aqueous fluids. A cola drink (pH 3.0) or red wine (pH 3.7) has an H concentration approximately 10,000 times that of blood (pH 7.4). The pH of an aqueou... |
water. These are common in biological systems and play important roles in metabolism and its regulation. The behavior of aqueous solutions of weak acids and bases is best understood if we first define some terms. Acids may be defined as proton donors and bases as proton acceptors. A proton donor and its corresponding ... |
C O OH NH3 CH2C O O H pKa = 2.34 NH3 CH2C O O NH2 CH2C O O H pKa = 9.60 H3PO4 H2PO4 H pKa = 2.14 H2PO4 2 H HPO4 pKa = 6.86 2 HPO4 3 H PO4 pKa = 12. 10 11 12 13 pH FIGURE 2–16 Conjugate acid-base pairs consist of a proton donor and a proton acceptor. Some compounds, such as acetic acid and ammonium ion, are monoprotic; ... |
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