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Matter The “stuff” of the universe Anything that has mass and takes up space States of matter Solid – has definite shape and volume Liquid – has definite volume, changeable shape Gas – has changeable shape and volume Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy The capacity to do work (put matter into motion) Types of energy PLAY Kinetic – energy in action Potential – energy of position; stored (inactive) energy Energy Concepts Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Forms of Energy Chemical – stored in the bonds of chemical substances Electrical – results from the movement of charged particles Mechanical – directly involved in moving matter Radiant or electromagnetic – energy traveling in waves (i.e., visible light, ultraviolet light, and X-rays) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy Form Conversions Energy is easily converted from one form to another During conversion, some energy is “lost” as heat Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Composition of Matter Elements – unique substances that cannot be broken down by ordinary chemical means Atoms – more-or-less identical building blocks for each element Atomic symbol – one- or two-letter chemical shorthand for each element Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Elements Each element has unique physical and chemical properties Physical properties – those detected with our senses Chemical properties – pertain to the way atoms interact with one another Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Elements of the Human Body Oxygen (O),Carbon (C),Hydrogen (H),Nitrogen (N) Lesser elements make up 3.9% of the body and include: Calcium (Ca), phosphorus (P), potassium (K), sulfur (S), sodium (Na), chlorine (Cl), magnesium (Mg), iodine (I), and iron (Fe) Trace elements make up less than 0.01% of the body They are required in minute amounts, and are found as part of enzymes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Atomic Structure The nucleus consists of neutrons and protons Neutrons – have no charge and a mass of one atomic mass unit (amu) Protons – have a positive charge and a mass of 1 amu Electrons are found orbiting the nucleus Electrons – have a negative charge and 1/2000 the mass of a proton (0 amu) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Models of the Atom Planetary Model – electrons move around the nucleus in fixed, circular orbits Orbital Model – regions around the nucleus in which electrons are most likely to be found Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Models of the Atom Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.1 Identification of Elements Atomic number – equal to the number of protons Mass number – equal to the mass of the protons and neutrons Atomic weight – average of the mass numbers of all isotopes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Identification of Elements Isotope – atoms with same number of protons but a different number of neutrons Radioisotopes – atoms that undergo spontaneous decay called radioactivity Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Identification of Elements: Atomic Structure Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.2 Identification of Elements: Isotopes of Hydrogen Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.3 Molecules and Compounds Molecule – two or more atoms held together by chemical bonds Compound – two or more different kinds of atoms chemically bonded together Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mixtures and Solutions Mixtures – two or more components physically intermixed (not chemically bonded) Solutions – homogeneous mixtures of components Solvent – substance present in greatest amount Solute – substance(s) present in smaller amounts Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Concentration of Solutions Percent, or parts per 100 parts Molarity, or moles per liter (M) A mole of an element or compound is equal to its atomic or molecular weight (sum of atomic weights) in grams Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Colloids and Suspensions Colloids (emulsions) – heterogeneous mixtures whose solutes do not settle out Suspensions – heterogeneous mixtures with visible solutes that tend to settle out Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mixtures Compared with Compounds No chemical bonding takes place in mixtures Most mixtures can be separated by physical means Mixtures can be heterogeneous or homogeneous Compounds cannot be separated by physical means All compounds are homogeneous Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemical Bonds Electron shells, or energy levels, surround the nucleus of an atom Bonds are formed using the electrons in the outermost energy level Valence shell – outermost energy level containing chemically active electrons Octet rule – except for the first shell which is full with two electrons, atoms interact in a manner to have eight electrons in their valence shell Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemically Inert Elements Inert elements have their outermost energy level fully occupied by electrons Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.4a Chemically Reactive Elements Reactive elements do not have their outermost energy level fully occupied by electrons Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.4b Types of Chemical Bonds Ionic Covalent Hydrogen Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ionic Bonds Ions are charged atoms resulting from the gain or loss of electrons Anions have gained one or more electrons Cations have lost one or more electrons Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Formation of an Ionic Bond Ionic bonds form between atoms by the transfer of one or more electrons Ionic compounds form crystals instead of individual molecules Example: NaCl (sodium chloride) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Formation of an Ionic Bond Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.5a Formation of an Ionic Bond Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.5b Covalent Bonds Covalent bonds are formed by the sharing of two or more electrons Electron sharing produces molecules Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Single Covalent Bonds Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.7a Double Covalent Bonds Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.7b Triple Covalent Bonds Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.7c Polar and Nonpolar Molecules Electrons shared equally between atoms produce nonpolar molecules Unequal sharing of electrons produces polar molecules Atoms with six or seven valence shell electrons are electronegative Atoms with one or two valence shell electrons are electropositive Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Comparison of Ionic, Polar Covalent, and Nonpolar Covalent Bonds Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.9 Hydrogen Bonds Too weak to bind atoms together Common in dipoles such as water Responsible for surface tension in water Important as intramolecular bonds, giving the molecule a three-dimensional shape PLAY Hydrogen Bonds Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hydrogen Bonds Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.10a Chemical Reactions Occur when chemical bonds are formed, rearranged, or broken Written in symbolic form using chemical equations Chemical equations contain: Number and type of reacting substances, and products produced Relative amounts of reactants and products Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Examples of Chemical Reactions Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Patterns of Chemical Reactions Combination reactions: Synthesis reactions which always involve bond formation A + B AB Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Patterns of Chemical Reactions Decomposition reactions: Molecules are broken down into smaller molecules AB A + B Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Patterns of Chemical Reactions Exchange reactions: Bonds are both made and broken AB + C AC + B Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Oxidation-Reduction (Redox) Reactions Reactants losing electrons are electron donors and are oxidized Reactants taking up electrons are electron acceptors and become reduced Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Energy Flow in Chemical Reactions Exergonic reactions – reactions that release energy Endergonic reactions – reactions whose products contain more potential energy than did its reactants Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Reversibility in Chemical Reactions All chemical reactions are theoretically reversible A + B AB AB A + B If neither a forward nor reverse reaction is dominant, chemical equilibrium is reached Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Rate of Chemical Reactions Temperature – chemical reactions proceed quicker at higher temperatures Particle size – the smaller the particle the faster the chemical reaction Concentration – higher reacting particle concentrations produce faster reactions Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Factors Influencing Rate of Chemical Reactions Catalysts – increase the rate of a reaction without being chemically changed Enzymes – biological catalysts Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Biochemistry Organic compounds Contain carbon, are covalently bonded, and are often large Inorganic compounds Do not contain carbon Water, salts, and many acids and bases Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Water High heat capacity – absorbs and releases large amounts of heat before changing temperature High heat of vaporization – changing from a liquid to a gas requires large amounts of heat Polar solvent properties – dissolves ionic substances, forms hydration layers around large charged molecules, and serves as the body’s major transport medium Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Properties of Water Reactivity – is an important part of hydrolysis and dehydration synthesis reactions Cushioning – resilient cushion around certain body organs PLAY InterActive Physiology®: Fluid, Electrolyte, and Acid/Base Balance: Introduction to Body Fluids Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Salts Inorganic compounds Contain cations other than H+ and anions other than OH– Are electrolytes; they conduct electrical currents Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Acids and Bases Acids release H+ and are therefore proton donors HCl H+ + Cl – Bases release OH– and are proton acceptors NaOH Na+ + OH– Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Acid-Base Concentration (pH) Acidic solutions have higher H+ concentration and therefore a lower pH Alkaline solutions have lower H+ concentration and therefore a higher pH Neutral solutions have equal H+ and OH– concentrations Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Acid-Base Concentration (pH) Acidic: pH 0–6.99 Basic: pH 7.01–14 Neutral: pH 7.00 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.13 Buffers Systems that resist abrupt and large swings in the pH of body fluids Carbonic acid-bicarbonate system Carbonic acid dissociates, reversibly releasing bicarbonate ions and protons The chemical equilibrium between carbonic acid and bicarbonate resists pH changes in the blood PLAY InterActive Physiology®: Fluid, Electrolyte, and Acid/Base Balance: Acid/Base Homeostasis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Organic Compounds Molecules unique to living systems contain carbon and hence are organic compounds They include: Carbohydrates Lipids Proteins Nucleic Acids Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Contain carbon, hydrogen, and oxygen Their major function is to supply a source of cellular food Examples: Monosaccharides or simple sugars Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.14a Carbohydrates Disaccharides or double sugars PLAY Disaccharides Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.14b Carbohydrates Polysaccharides or polymers of simple sugars PLAY Polysaccharides Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.14c Lipids Contain C, H, and O, but the proportion of oxygen in lipids is less than in carbohydrates Examples: Neutral fats or triglycerides Phospholipids Steroids Eicosanoids PLAY Fats Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neutral Fats (Triglycerides) Composed of three fatty acids bonded to a glycerol molecule Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.15a Neutral Fats (Triglycerides) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Other Lipids Phospholipids – modified triglycerides with two fatty acid groups and a phosphorus group Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.15b Other Lipids Steroids – flat molecules with four interlocking hydrocarbon rings Eicosanoids – 20-carbon fatty acids found in cell membranes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.15c Representative Lipids Found in the Body Neutral fats – found in subcutaneous tissue and around organs Phospholipids – chief component of cell membranes Steroids – cholesterol, bile salts, vitamin D, sex hormones, and adrenal cortical hormones Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Representative Lipids Found in the Body Fat-soluble vitamins – vitamins A, E, and K Eicosanoids – prostaglandins, leukotrienes, and thromboxanes Lipoproteins – transport fatty acids and cholesterol in the bloodstream Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids Building blocks of protein, containing an amino group and a carboxyl group Amino group NH2 Carboxyl groups COOH Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.16a–c Protein Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds Peptide bond H H R O N C C OH H Amino acid + H H R O N C C OH H Amino acid Dehydration H O 2 synthesis Hydrolysis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings H H2O H R O H R O N C C N C C H H OH Dipeptide Figure 2.17 Structural Levels of Proteins Primary – amino acid sequence Secondary – alpha helices or beta pleated sheets PLAY Chemistry of Life: Introduction to Protein Structure PLAY Chemistry of Life: Proteins: Primary Structure PLAY Chemistry of Life: Proteins: Secondary Structure Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins Tertiary – superimposed folding of secondary structures Quaternary – polypeptide chains linked together in a specific manner PLAY Chemistry of Life: Proteins: Tertiary Structure PLAY Chemistry of Life: Proteins: Quaternary Structure Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.18a–c Structural Levels of Proteins Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.18b,d,e Fibrous and Globular Proteins Fibrous proteins Extended and strand-like proteins Examples: keratin, elastin, collagen, and certain contractile fibers Globular proteins Compact, spherical proteins with tertiary and quaternary structures Examples: antibodies, hormones, and enzymes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Protein Denuaturation Reversible unfolding of proteins due to drops in pH and/or increased temperature Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.19a Protein Denuaturation Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.19b Molecular Chaperones (Chaperonins) Help other proteins to achieve their functional three-dimensional shape Maintain folding integrity Assist in translocation of proteins across membranes Promote the breakdown of damaged or denatured proteins Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Characteristics of Enzymes Most are globular proteins that act as biological catalysts Holoenzymes consist of an apoenzyme (protein) and a cofactor (usually an ion) Enzymes are chemically specific Frequently named for the type of reaction they catalyze Enzyme names usually end in -ase Lower activation energy Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Characteristics of Enzymes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.20 Mechanism of Enzyme Action Enzyme binds with substrate Product is formed at a lower activation energy Product is released PLAY How Enzymes Work Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active site Amino acids + Enzyme (E) Substrates (S) Enzyme-substrate complex (E-S) H2O Free enzyme (E) Peptide bond Internal rearrangements leading to catalysis Dipeptide product (P) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.21 Nucleic Acids Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus Their structural unit, the nucleotide, is composed of N-containing base, a pentose sugar, and a phosphate group Five nitrogen bases contribute to nucleotide structure – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U) Two major classes – DNA and RNA Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Deoxyribonucleic Acid (DNA) Double-stranded helical molecule found in the nucleus of the cell Replicates itself before the cell divides, ensuring genetic continuity Provides instructions for protein synthesis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Structure of DNA Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.22a Structure of DNA Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.22b Ribonucleic Acid (RNA) Single-stranded molecule found in both the nucleus and the cytoplasm of a cell Uses the nitrogenous base uracil instead of thymine Three varieties of RNA: messenger RNA, transfer RNA, and ribosomal RNA Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adenosine Triphosphate (ATP) Source of immediately usable energy for the cell Adenine-containing RNA nucleotide with three phosphate groups Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adenosine Triphosphate (ATP) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.23 Membrane protein Pi P Solute Solute transported (a) Transport work ADP + Pi ATP Relaxed smooth muscle cell Contracted smooth muscle cell (b) Mechanical work Pi X P X Y + Y Reactants Product made (c) Chemical work Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 2.24