Chapter 2 Lecture Outline PDF

1 Chapter 2 Lecture Outline © 2019 McGraw-Hill Education  2.1 Atomic Structure 2 Learning Objectives 1...

1 Chapter 2 Lecture Outline © 2019 McGraw-Hill Education  2.1 Atomic Structure 2 Learning Objectives 1 1. Define matter, and list its three forms. 2. Describe and differentiate among the subatomic particles that compose atoms. 3. Explain the arrangement of elements in the periodic table based on atomic number. 4. Diagram the structure of an atom. © 2019 McGraw-Hill Education  2.1 Atomic Structure 3 Learning Objectives 2 5. Describe an isotope. 6. Explain how radioisotopes differ from other types of isotopes. 7. Describe how elements are organized in the periodic table based on the valence electron number. 8. State the octet rule. © 2019 McGraw-Hill Education  2.1a Matter, Atoms, Elements, 4 and the Periodic Table 1 Matter has mass and occupies space 3 forms of matter: Solid (e.g., bone) Liquid (e.g., blood) Gas (e.g., oxygen) Atom is the smallest particle exhibiting chemical properties of an element (one type of atom) 92 naturally occurring elements make up matter © 2019 McGraw-Hill Education  5 Periodic Table of Elements Figure 2.1a © 2019 McGraw-Hill Education  Most Common Elements of the 6 Human Body Figure 2.1b © 2019 McGraw-Hill Education  2.1a Matter, Atoms, Elements, 7 and the Periodic Table 2 Components of an atom Atoms composed of three subatomic particles Neutrons Mass of one atomic mass unit (amu) No charge Protons Mass of one amu Positive charge of one (1) Electrons 1/1800th of the mass of a proton or neutron Negative charge of one (1) Located at varying distance from the nucleus in regions © 2019 McGraw-Hill Education called orbitals  2.1a Matter, Atoms, Elements, 8 and the Periodic Table 3 Periodic table Chemical symbol Unique to each element Usually identified by first letter, or first letter plus an additional letter, e.g., C is carbon Atomic number Number of protons in an atom of the element Located above symbol name Elements arranged by anatomic number within rows Average atomic mass Mass of both protons and neutrons Shown below the element’s symbol on the table © 2019 McGraw-Hill Education  2.1a Matter, Atoms, Elements, 9 and the Periodic Table 4 Determining the number of subatomic particles Proton number atomic number Neutron number atomic mass atomic number Neutron number (p n) p Neutron number of Na 23 11 12 Electron number proton number © 2019 McGraw-Hill Education  2.1a Matter, Atoms, Elements, 10 and the Periodic Table 5 Diagramming atomic structures An atom has “shells” of electrons surrounding the nucleus Each shell has given energy level Each shell holds a limited number of electrons Innermost shell: two electrons, Figure © 2019 McGraw-Hill Education 2.2b  11 2.1b Isotopes 1 Isotopes are different atoms of the same element Same number of protons and electrons; different number of neutrons Identical chemical characteristics; different atomic masses E.g., carbon exists in three isotopes Carbon-12, with 6 neutrons Most prevalent type Carbon-13, with 7 neutrons Figure 2.3 Carbon-14, with 8 neutrons © 2019 McGraw-Hill Education  12 2.1b Isotopes 2 Weighted average of atomic mass for all isotopes is the average atomic mass Radioisotopes Contain excess neutrons, so unstable Lose nuclear components in the form of high energy radiation Alpha particles Beta particles Gamma rays © 2019 McGraw-Hill Education  13 2.1b Isotopes 3 Physical half-life The time for 50% of radioisotope to become stable Can vary from a few hours to thousands of years Biological half-life The time required for half of the radioactive material from a test to be eliminated from the body © 2019 McGraw-Hill Education  Clinical View: Medical Imaging 14 of the Thyroid Gland Using Iodine Radioisotopes Radioisotopes introduced into the body during medical procedures Used by cells in a similar manner to nonradioisotopes Can trace products of metabolic reactions that use these elements Thyroid gland darker in areas where less radioactive iodine taken up Can help locate a nodule © 2019 McGraw-Hill Education 2.1c Chemical Stability and the 15 Octet Rule Periodic table is organized into columns based on number of electrons in outer shell, referred to as the valence shell Column IA shows hydrogen, lithium, sodium, potassium All with one electron in their outer shell Each consecutive column has one additional electron in outer shell Elements in column VIIA each have a full valence shell Results in chemical stability © 2019 McGraw-Hill Education  Table 16 Based on Valence Shell Elements tendElectrons to lose, gain, or share electrons to obtain complete outer shells with eight electrons Known as the octet rule Figure 2.4 © 2019 McGraw-Hill Education  Section 2.1 What did you 17 learn? 1. What subatomic particles determine the mass of an atom? What subatomic particles determine the charge of an atom? 2. Diagram the atomic structure of chlorine —the atomic number is 17 and the mass number is 35. 3. Do isotopes represent the same element? Do they have the same number of protons, neutrons, or electrons? Describe a radioisotope. © 2019 McGraw-Hill Education  2.2 Ions and Ionic Compounds 18 Learning Objectives 9. Define an ion. 10.List some common ions in the body. 11.Differentiate between cations and anions. 12.Describe how charges are assigned to ions. 13.Define an ionic bond. 14.Describe an ionic compound of NaCl. 15.List other examples of ionic compounds. © 2019 McGraw-Hill Education  19 2.2 Ions and Ionic Compounds Chemical compounds Stable associations between two or more elements combined in a fixed ratio Classified as ionic or molecular Ionic compounds are structures composed of ions held together in a lattice by ionic bonds © 2019 McGraw-Hill Education  20 2.2a Ions 1 Ions Atoms with a positive or a negative charge Produced from loss or gain of one or more electrons Significant physiological functions E.g., K is used to sports drinks to replace the K lost in sweat E.g., K in a large dose is used in some states for lethal injection © 2019 McGraw-Hill Education  21 2.2a Ions 2 Losing electrons and the formation of cations Sodium can reach stability by donating an electron Now satisfies the octet rule Now has 11 protons and 10 electrons Charge is 1 Cations are ions with a positive charge © 2019 McGraw-Hill Education  22 2.2a Ions 3 Gaining electrons and the formation of anions Chlorine reaches stability by gaining an electron Now satisfies the octet rule Now has 17 protons and 18 electrons Charge is 1 Anions are ions with negative charge Polyatomic ions are anions with more © 2019 McGraw-Hill Education  23 2.2b Ionic Bonds Ionic bonds Cations and anions bound by electrostatic forces Form salts E.g., table salt (NaCl) Each sodium atom loses one outer shell electron to a chlorine atom Sodium and chlorine ions are held together by ionic bonds in a lattice crystal structure (ionic compound) E.g., magnesium chloride Each magnesium atom loses one electron to each of the two chlorine atoms © 2019 McGraw-Hill Education  Formation of an Ionic Bond 24 Involving Sodium and Chloride Figure 2.5 © 2019 McGraw-Hill Education  Section 2.2 What did you 25 learn? 5. List the common cations and anions of the human body, including their name and symbol. 6. On the periodic table (see figure 2.1), highlight the elements that form the common ions of the human body (do not include the polyatomic ions). 7. Explain how and why ions form based on the octet rule. 8. Could an ionic bond form between two cations or between two anions? Explain. © 2019 McGraw-Hill Education  2.3 Covalent Bonding, 26 Molecules, and Molecular Compounds Learning Objectives 1 16.Define a molecular formula. 17.Describe a structural formula, and explain its use in differentiating isomers. 18.Describe a covalent bond and explain its formation based on the octet rule. 19.List the four most common elements in the human body. 20.Distinguish between single, double, and triple covalent bonds. © 2019 McGraw-Hill Education  2.3 Covalent Bonding, 27 Molecules, and Molecular Compounds Learning Objectives 2 21.Explain polar and nonpolar covalent bonds. 22.Describe the difference between a nonpolar molecule and a polar molecule. 23.Define an amphipathic molecule. 24.Describe hydrogen bonding between polar molecules. 25.List and define the intermolecular attractions between nonpolar molecules. © 2019 McGraw-Hill Education  2.3 Covalent Bonding, 28 Molecules, and Molecular Compounds Covalently bonded molecule Electrons shared between atoms of two or more different elements Termed molecular compounds E.g., carbon dioxide (CO2), but not molecular oxygen (O2) © 2019 McGraw-Hill Education  2.3a Chemical Formulas: 29 Molecular and Structural 1 Molecular formula Indicates number and type of atoms E.g., carbonic acid (H2CO3) Structural formula Indicates number and type of atoms Indicates arrangement of atoms within the molecule E.g., OCO (carbon dioxide) Allows differentiation of isomers © 2019 McGraw-Hill Education  2.3a Chemical Formulas: 30 Molecular and Structural 2 Glucose vs. galactose vs. fructose Same molecular formula 6 carbon, 12 hydrogen, 6 oxygen Atoms arranged differently Isomers may have different chemical properties Figure 2.6 © 2019 McGraw-Hill Education  31 2.3b Covalent Bonds 1 Covalent bond Atoms share electrons Occurs when both atoms require electrons Occurs with atoms with 4 to 7 electrons in outer shell Formed commonly in human body using Hydrogen (H) Oxygen (O) Nitrogen (N) Carbon (C) © 2019 McGraw-Hill Education  32 2.3b Covalent Bonds 2 Number of covalent bonds an atom can form Simplest occurs between two hydrogen atoms Each sharing its single electron Oxygen needs two electrons to complete outer shell Forms two covalent bonds Nitrogen forms three bonds © 2019 McGraw-Hill Education  33 2.3b Covalent Bonds 3 Single, double, and triple covalent bonds Single covalent bond One pair of electrons shared E.g., between two hydrogen atoms Double covalent bond Two pairs of electrons shared E.g., between two oxygen atoms Triple covalent bond Three pairs of electrons shared E.g., between two nitrogen atoms © 2019 McGraw-Hill Education  Single, Double, and Triple 34 Covalent Bonds Figure 2.7 © 2019 McGraw-Hill Education  35 2.3b Covalent Bonds 4 Carbon needs four electrons to satisfy octet rule Can be obtained in a number of ways Figure 2.8 © 2019 McGraw-Hill Education  36 2.3b Covalent Bonds 5 Carbon skeleton formation Carbon Bonds in straight chains, branched chains, or rings Carbon present where lines meet at an angle Additional atoms are hydrogen Figure 2.9 © 2019 McGraw-Hill Education  37 2.3b Covalent Bonds 6 Nonpolar and polar covalent bonds Electronegativity—relative attraction of each atom for electrons Determines how electrons are shared in covalent bonds Two atoms of same element have equal attraction for electrons Resulting bond is nonpolar covalent bond Sharing of electrons unequally polar covalent bond © 2019 McGraw-Hill Education  38 2.3b Covalent Bonds 7 Nonpolar and polar covalent bonds (continued) In periodic table, electronegativity increases From left to right across row From bottom to top in column For 4 most common elements composing living organisms © 2019 McGraw-Hill Education  39 2.3b Covalent Bonds 8 Electrons have negative charge More electronegative atom develops a partial negative charge Less electronegative atom develops a partial positive charge Written using Greek delta () followed by superscript plus or minus Exception to rule of polar bond forming between two different atoms Carbon bonding with hydrogen © 2019 McGraw-Hill Education  2.3c Nonpolar, Polar, and 40 Amphipathic Molecules 1 Covalent bonds may be polar or nonpolar Nonpolar molecules contain nonpolar covalent bonds E.g., O—O and C—H are nonpolar bonds Polar molecules contain polar covalent bonds O—H is a polar bond in the polar molecule water (H2O) Nonpolar molecules may contain polar © 2019 McGraw-Hill Education  2.3c Nonpolar, Polar, and 41 Amphipathic Molecules 2 Amphipathic molecules Large molecules with both polar and nonpolar regions E.g., phospholipids © 2019 McGraw-Hill Education  Nonpolar, Polar, and 42 Amphipathic Molecules Figure 2.10 © 2019 McGraw-Hill Education  2.3d Intermolecular 43 Attractions 1 Intermolecular attractions Weak chemical attractions between molecules Important for shape of complex molecules E.g., DNA and proteins Hydrogen bond Forms between polar molecules Attraction between partially positive hydrogen atom and a partially negative atom Individually weak, collectively strong Influences how water molecules behave © 2019 McGraw-Hill Education  44 Hydrogen Bonding Figure 2.11 © 2019 McGraw-Hill Education  2.3d Intermolecular 45 Attractions 2 Other intermolecular attractions Van der Waals forces Nonpolar molecules Electrons orbiting nucleus briefly, unevenly distributed Induce unequal distribution of adjacent atom of another nonpolar molecule Individually weak Hydrophobic interactions Nonpolar molecules placed in a polar substance © 2019 McGraw-Hill Education If occurring between parts of large molecule,  Section 2.3 What did you 46 learn? 9. What information about a molecule is gained by a structural formula? How does a structural formula differ from a molecular formula? 10. What is an isomer? 11. Explain covalent bond formation in terms of chemical stability. 12. Assign the partial charges between nitrogen and hydrogen (N—H) in a polar covalent bond. 13. Why are some covalent bonds nonpolar and others polar? Identify the exception to the rule that polar covalent bonds are formed between two different types of atoms. 14. Are O2 and CO2 nonpolar or polar molecules? 15. What is the name of the intermolecular attraction © 2019 McGraw-Hill Education between a partially charged hydrogen of one polar  2.4 Molecular Structure and 47 Properties of Water Learning Objectives 26.Describe the molecular structure of water and how each water molecule can form four hydrogen bonds. 27.List the different properties of water, and provide an example of the importance of each property within the body. 28.Compare substances that dissolve in water with those that both dissolve and dissociate in water. Distinguish between electrolytes and nonelectrolytes. 29.Describe the chemical interactions of nonpolar substances and water. © 2019 McGraw-Hill Education  2.4a Molecular Structure of 48 Water Water Composes two-thirds of the human body by weight Polar molecule One oxygen atom bonded to two hydrogen atoms Oxygen atom has two partial negative charges Hydrogens have single partial positive charge Can form four hydrogen Figure bonds with adjacent 2.12 © 2019 McGraw-Hill Education  49 2.4b Properties of Water 1 Phases of water 3 phases of water, depending on temperature: Gas (water vapor) Substances with low molecular mass Liquid (water) Almost all water in the body Liquid at room temperature due to hydrogen bonding © 2019 McGraw-Hill Education  50 2.4b Properties of Water 2 Phases of water (continued ) Functions of liquid water: Transports Substances dissolved in water move easily throughout body Lubricates Decreases friction between body structures Cushions Absorbs sudden force of body movements Excretes wastes © 2019 McGraw-Hill Education Unwanted substances dissolve in water are  51 2.4b Properties of Water 3 Cohesion, surface tension, and adhesion Cohesion Attraction between water molecules due to hydrogen bonding Surface tension Inward pulling of cohesive forces at surface of water Causes moist sacs of air in lungs to collapse Surfactant, a lipoprotein, prevents collapse Adhesion Attraction between water molecules and a © 2019 McGraw-Hill Education  52 2.4b Properties of Water 4 High specific heat and high heat of vaporization Temperature Measure of kinetic energy of atoms or molecules within a substance Specific heat Amount of energy required to increase temperature of 1 gram of a substance by 1 degree Celsius Water’s value extremely high due to energy needed to break hydrogen bonds © 2019 McGraw-Hill Education  53 2.4b Properties of Water 5 High specific heat and high heat of vaporization (continued ) Heat of vaporization Heat required for release of molecules from a liquid phase into a gaseous phase for 1 gram of a substance Water’s value very high due to hydrogen bonding Sweating cools body © 2019 McGraw-Hill Education Excess heat dissipated as water evaporates  2.4c Water as the Universal 54 Solvent 1 Water—solvent of the body Solutes are substances that dissolve in water Water is called universal solvent because most substances dissolve in it Chemical properties of a substance determine whether it will dissolve or not © 2019 McGraw-Hill Education  2.4c Water as the Universal 55 Solvent 2 Substances that dissolve in water Polar molecules and ions Hydrophilic means “water-loving” Water surrounds substances, forms a hydration shell Some substances dissolve but remain intact E.g., glucose and alcohol Nonelectrolytes remain intact but do not conduct current Substances dissolve and dissociate (separate) NaCl dissociates into Na and Cl ions © 2019 McGraw-Hill Education Acids and bases, such as HCl  2.4c Water as the Universal 56 Solvent 3 Substances that do not dissolve in water Nonpolar molecules Hydrophobic means “water-fearing” Hydrophobic exclusion—cohesive water molecules “force out” nonpolar molecules Hydrophobic interaction—“excluded molecules” Hydrophobic substances require carrier proteins to be transported within the blood E.g., fats and cholesterol are unable to dissolve © 2019 McGraw-Hill Education  2.4c Water as the Universal 57 Solvent 4 Substances that partially dissolve in water Amphipathic molecules have polar and nonpolar regions Polar portion of molecule dissolves in water Nonpolar portion repelled by water Phospholipid molecules are amphipathic Polar heads have contact with water Nonpolar tails group together Results in bilayers of phospholipid molecules E.g., membranes of a cell Other amphipathic molecules form a micelle © 2019 McGraw-Hill Education  Substance Interaction with 58 Water © 2019 McGraw-Hill Education  Section 2.4 What did you 59 learn? 16.What is the intermolecular bond that is significant in determining the properties of water? 17.Which property of water contributes to the need to produce surfactant and prevent collapse of the alveoli? Which property contributes to body temperature regulation through sweating? Why is sweating less effective in cooling the body on a humid day? 18.How does the interaction of a nonelectrolyte and water differ from the interaction of an electrolyte and water? Give examples of each. © 2019 McGraw-Hill Education  2.5 Acidic and Basic Solutions, 60 pH, and Buffers Learning Objectives 31.Describe what is formed when water molecules dissociate. 32.Explain the difference between an acid and a base. 33.Define pH and explain the relative pH values of both acids and bases. 34.Explain neutralization, and describe how the neutralization of both an acid and a base occur. 35.Describe the action of a buffer. © 2019 McGraw-Hill Education  61 2.5a Water: A Neutral Solvent Water spontaneously dissociates to form ions Bond between oxygen and hydrogen breaks apart spontaneously 1/10,000,000 ions per liter OH group hydroxide ion (OH) Hydrogen ion transferred to a second water molecule Hydronium ion (H3O) Equal numbers of positive hydrogen ions and negative hydroxyl ions produced Water remains neutral H2O H2O H3O OH simplified to © 2019 McGraw-Hill Education  62 2.5b Acids and Bases 1 Acid dissociates in water to produce H and an anion Proton donor Increases concentration of free H More dissociation of H with stronger acids E.g., HCl in the stomach Less dissociation of H with weaker acids E.g., carbonic acid in the blood Substance A (an acid in water) H Anion © 2019 McGraw-Hill Education  63 2.5b Acids and Bases 2 Base accepts H when added to solution Proton acceptor Decreases concentration of free H More absorption of H with stronger bases E.g., ammonia and bleach Less absorption of H with weaker bases E.g., bicarbonate in blood and in secretions released into small intestine Substance B (a base in water) H B— H © 2019 McGraw-Hill Education  2.5c pH, Neutralization, and 64 the Action of Buffers 1 pH is a measure of H Relative amount of H in a solution Range between 0 and 14 The pH of plain water is 7 Water dissociates to produce 1/10,000,000 of H and OH ions per liter Equal to 1 107 or to 0.0000001 pH and H concentration are inversely related Inverse of the log for a given H concentration As H concentration increases, pH decreases, becoming more acidic As H concentration decreases, pH increases, becoming more base (alkaline) © 2019 McGraw-Hill Education  2.5c pH, Neutralization, and 65 the Action of Buffers Interpreting the pH scale 2 Solutions with equal concentrations of H and OH Are neutral Have a pH of 7 Solutions with greater H than OH Are acidic Have a pH 7 Solutions with greater OH than H Are basic (alkaline) Have a pH 7 Moving from one increment to next is a 10-fold change © 2019 McGraw-Hill Education  66 pH Figure 2.15 © 2019 McGraw-Hill Education  2.5c pH, Neutralization, and 67 the Action of Buffers 3 Neutralization When an acidic or basic solution is returned to neutral (pH 7) Acids neutralized by adding base E.g., medications to neutralize stomach acid must contain a base Bases neutralized by adding acid Buffers Help prevent pH changes if excess acid or base is added Act to accept H from excess acid or donate H to neutralize base © 2019 McGraw-Hill Education  Section 2.5 What did you 68 learn? 20.Explain why water is neutral. 21.Which type of substance releases H when added to water? 22.What is the general relationship of [H] and pH? 23.Why are buffers important, and how do they function to help maintain pH? © 2019 McGraw-Hill Education  2.6 Water Mixtures 69 Learning Objectives 2 1. Compare and contrast the three different types of water mixtures. 2. Explain how an emulsion differs from other types of mixtures. 3. Explain the different ways to express the concentration of solute in a solution. © 2019 McGraw-Hill Education  70 2.6 Water Mixtures Mixtures are formed from combining two or more substances Two defining features: Substances mixed are not chemically changed Substances can be separated by physical means E.g., evaporation or filtering © 2019 McGraw-Hill Education  2.6a Categories of Water 71 Mixtures 1 Three categories of water mixtures: 1. Suspension: material larger in size than 1 mm mixed with water E.g., blood cells within plasma or sand in water Does not remain mixed unless in motion Appears cloudy or opaque; scatters light 2. Colloid: smaller particles than a suspension, but larger than those in a solution E.g., fluid in cell cytosol and fluid in blood plasma Remains mixed when not in motion Scatters light © 2019 McGraw-Hill Education  2.6a Categories of Water 72 Mixtures 2 Three categories of water mixtures (continued ) 3. Solution: homogeneous mixture of material smaller than 1 nanometer Dissolves in water Does not scatter light; does not settle if solution not in motion E.g., sugar water, salt water, blood plasma Special category of suspension—emulsion Water and a nonpolar liquid substance E.g., oil and vinegar salad dressing or breast milk © 2019 McGraw-Hill Education  73 Mixtures and an Emulsion Figure 2.16 © 2019 McGraw-Hill Education  2.7a Biological 74 Macromolecules: General Characteristics 1 Biological macromolecules—large organic molecules synthesized (produced/made) by the body Always contain carbon, hydrogen, and oxygen Some may also have nitrogen, phosphorus, or sulfur “Carbon skeletons” can take a variety of forms Hydrocarbons – contain only carbon and hydrogen atoms Contain functional groups © 2019 McGraw-Hill Education  2.7a Biological 75 Macromolecules: General Characteristics 2 Polymers Molecules made of monomers (repeating subunits) Carbohydrates contain sugar monomers Nucleic acids contain nucleotide monomers Proteins contain amino acid monomers © 2019 McGraw-Hill Education  2.7a Biological 76 Macromolecules: General Characteristics 3 Dehydration synthesis (condensation) Occurs during the synthesis of biomolecules One subunit looses an —H Other subunit loses an —OH New covalent bond formed and water produced (water removed) Hydrolysis Occurs during the breakdown of biomolecules Water is used (added) Figure An —H added to one subunit © 2019 McGraw-Hill Education 2.17  77 2.7b Lipids 1 Lipids Diverse group of fatty, water-insoluble molecules Function as stored energy, cellular membrane components, hormones Four primary classes: 1. Triglycerides (most abundant) 2. Phospholipids 3. Steroids © 2019 McGraw-Hill Education  78 2.7b Lipids 2 Triglycerides used for long-term energy storage Formed from glycerol and three fatty acids Fatty acids vary in length and number of double bonds Saturated, lack double bonds Unsaturated, one double bond Polyunsaturated, two or more double bonds Adipose tissue stores triglycerides Lipogenesis—formation of triglycerides when conditions of excess nutrients exist © 2019 McGraw-Hill Education  79 Triglycerides Figure 2.18 © 2019 McGraw-Hill Education  80 2.7b Lipids 3 Phospholipids Amphipathic molecules that form chemical barriers of cell membranes Phospholipid structure similar to a triglyceride Except one end of the glycerol has a polar phosphate group Glycerol, phosphate, and organic groups are polar Form hydrophilic head © 2019 McGraw-Hill Education  81 2.7b Lipids 4 Steroids Composed of hydrocarbons arranged in multiringed structure Four carbon rings; three have 6 carbon atoms, one has 5 carbon atoms Differ in side chains extending from their rings Cholesterol Component of animal plasma membranes Precursor to other steroid synthesis Steroid hormones (e.g., testosterone and estrogen) Bile salts © 2019 McGraw-Hill Education  82 2.7b Lipids 5 Eicosanoids Modified 20-carbon fatty acids Synthesized from arachidonic acid, membrane component Local signaling molecules Primary functions in inflammatory response and nervous system communication Four classes 1. Prostaglandins 2. Prostacyclins 3. Thromboxanes © 2019 McGraw-Hill Education  Section 2.7b What did you 83 learn? 30.Do lipid molecules typically dissolve in water? Explain. 31.Which class of lipids forms cell membranes? What characteristic allows it to perform this function? © 2019 McGraw-Hill Education  Clinical View—Fatty Acids: 84 Saturated, Unsaturated, and Trans Fats Most animal fats are saturated Most are solid at room temperature Most vegetable fats are unsaturated Most are liquid at room temperature Generally healthier Can be converted to saturated fats through hydrogenation Partial hydrogenation may lead to trans fats Increase the risk of heart attack and stroke © 2019 McGraw-Hill Education  85 2.7c Carbohydrates 1 Carbohydrates An —H and an — OH are usually attached to every carbon Chemical formula is (CH2O)n n number of carbon atoms Monosaccharides Simple sugar monomers Disaccharides Formed from two monosaccharides Polysaccharides © 2019 McGraw-Hill Education  86 2.7c Carbohydrates 2 Glucose Six-carbon carbohydrate Most common monosaccharide Primary nutrient supplying energy to cells Concentration must be carefully maintained Glycogen Liver and skeletal muscle store excess glucose, then bind glucose monomers together (glycogenesis) Liver hydrolyzes glycogen into glucose as needed (glycogenolysis) Liver can also form glucose from noncarb sources (gluconeogenesis) © 2019 McGraw-Hill Education  87 Glucose and Glycogen Figure 2.19 © 2019 McGraw-Hill Education  88 2.7c Carbohydrates 3 Other types of carbohydrates Hexose monosaccharides Glucose isomers (e.g., galactose and fructose) Five-carbon monosaccharides (pentose sugars) E.g., ribose and deoxyribose Disaccharides—two simple sugars bonded together Most common are sucrose (table sugar), © 2019 McGraw-Hill Education lactose (milk sugar), and maltose (malt sugar)  89 2.7c Carbohydrates 4 Other types of carbohydrates (continued ) Polysaccharides—three or more sugars Glycogen most common in animals Starch and cellulose found in plants Plant starch is a major nutritional source of glucose for humans Cellulose is a source of fiber (nondigestible) © 2019 McGraw-Hill Education  90 Other Simple Carbohydrates Figure 2.20 © 2019 McGraw-Hill Education  Section 2.7c What did you 91 learn? 32.What is the repeating monomer of glycogen? Where is glycogen stored in the body? 33.For each of the following, indicate if it is a monosaccharide, disaccharide, or polysaccharide: fructose, galactose, glucose, glycogen, lactose, maltose, starch, and sucrose. © 2019 McGraw-Hill Education  92 2.7d Nucleic Acids 1 Nucleic acids Store and transfer genetic information Two classes of nucleic acid Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) Both are polymers composed of nucleotide monomers Monomers are linked covalently through phosphodiester bonds © 2019 McGraw-Hill Education  93 Nucleotide Monomer 3 components: 1. Sugar Five-carbon pentose 1. Phosphate group Attached at carbon 5 of sugar 1. Nitrogenous base Attached to same sugar at carbon one Single-ring or double- Figure © 2019 McGraw-Hill Education ring structure 2.21a  94 2.7d Nucleic Acids 2 Five types of nitrogenous bases Three are pyrimidines—single-ring bases Cytosine Uracil Thymine Two are purines—double-ring bases Adenine Guanine Nitrogenous bases within either group differ in functional groups attached to ring © 2019 McGraw-Hill Education  95 Nitrogenous Bases Figure 2.21b © 2019 McGraw-Hill Education  96 2.7d Nucleic Acids 3 Deoxyribonucleic acid (DNA) Double-stranded nucleic acid Located in chromosomes in nucleus and in mitochondria Deoxyribose sugar, phosphate, and one of four nitrogenous bases Adenine, guanine, cystosine, thymine No uracil Double strands held together by hydrogen bonds Form between complementary bases Thymine paired with adenine © 2019 McGraw-Hill Education Guanine paired with cytosine  97 2.7d Nucleic Acids 4 Ribonucleic acid (RNA) Single-stranded nucleic acid Located in nucleus and in cytoplasm of cell Ribose sugar, phosphate, and one of four nitrogenous bases Adenine Guanine Cystosine Uracil No thymine © 2019 McGraw-Hill Education  98 RNA and DNA Figure 2.21c-d © 2019 McGraw-Hill Education  99 ATP Adenosine triphosphate (ATP) Nucleotide composed of nitrogenous base adenine, a ribose sugar, and three phosphate groups Central molecule in transfer of chemical energy within cell Covalent bonds between last two phosphate groups are unique, energy rich Release energy when broken Important nucleotide-containing molecules Nicotinamide adenine dinucleotide NAD+(ox)/NADH(red Flavin adenine dinucleotide FAD+(ox)/FADH2(reduced) Both participate in production of ATP Figure © 2019 McGraw-Hill Education 2.22  Section 2.7d What did you 100 learn? 34.What is the general function of nucleic acids? 35.What are the structural differences between RNA and DNA? © 2019 McGraw-Hill Education  101 2.7e Proteins 1 Functions of proteins: Serve as catalysts (enzymes) in metabolic reactions Act in defense Aid in transport Contribute to structural support Cause movement Perform regulation Provide storage © 2019 McGraw-Hill Education  102 2.7e Proteins 2 General protein structure One or more strands of amino acid monomers 20 different amino acids (essential) found in living organisms Each has an amine and a carboxyl functional group Both covalently linked to same carbon atom Carbon also covalently bonded to a hydrogen and different side chain © 2019 McGraw-Hill Education  103 2.7e Proteins 3 General protein structure (continued ) Amino acids are covalently linked by peptide bonds Formed during dehydration synthesis reaction between amine group of one amino acid and the carboxylic group of another —H lost from the amine group — OH lost from the carboxylic acid of another amino acid N-terminal end has free amine group C-terminal end has free carboxyl group © 2019 McGraw-Hill Education  104 Proteins Figure 2.23 © 2019 McGraw-Hill Education  105 2.7e Proteins 4 General protein structure (continued ) Strands of amino acids Oligopeptide: between 3 and 20 amino acids Polypeptide: between 21 and 199 amino acids Protein: more than 200 amino acids Glycoproteins are proteins with carbohydrate attached E.g., glycoproteins on erythrocytes determining ABO blood groups © 2019 McGraw-Hill Education  Section 2.7e What did you 106 learn? 36.What are the monomers of proteins and the name of the bond between them? 37.What are the names of structures that contain 2 amino acids, 3 to 20 amino acids, 21 to 199 amino acids, and 200 or more amino acids? What general term is used to refer to any of these structures, except a structure composed of 2 amino acids? © 2019 McGraw-Hill Education  2.8 Protein Structure 107 Learning Objectives 1 54.Name the categories of amino acids. 55.Distinguish between nonpolar, polar, and charged amino acids. 56.Give examples of amino acids with special characteristics. © 2019 McGraw-Hill Education  2.8 Protein Structure 108 Learning Objectives 2 57.Describe the different types of intramolecular (or intermolecular) attractions that participate in both the folding of a protein and in maintaining its three-dimensional shape. 58.Distinguish between the four structural hierarchy levels of proteins. 59.Explain what is meant by denaturation, and list factors that can cause it. © 2019 McGraw-Hill Education  109 2.8a Categories of Amino Acids 1 Organized into groups based on their R group Nonpolar amino acids Contain R groups with hydrogen or hydrocarbons Group with other nonpolar amino acids by hydrophobic interactions Polar amino acids Contain R groups with other elements besides hydrogen or hydrocarbons © 2019 McGraw-Hill Education  110 2.8a Categories of Amino Acids 2 Organized into groups based on their R group (continued ) Charged amino acids Contain R groups with a negative or a positive charge Form ionic bonds between negatively and positively charged amino acids Hydrophilic Amino acids with special functions Proline can cause a bend in the protein chain Cysteine can form disulfide bond © 2019 McGraw-Hill Education Methionine, first amino during protein synthesis  111 Amino Acids Figure 2.25 © 2019 McGraw-Hill Education  2.8b Amino Acid Sequence and 112 Protein Conformation 1 Primary structure—linear sequence of amino acids Figure © 2019 McGraw-Hill Education  2.8b Amino Acid Sequence and 113 Protein Conformation 2 Conformation—three-dimensional shape of the protein Crucial for protein function Levels of organization beyond primary structure Arrangements dependent upon intramolecular attractions between amino acids Obtained through folding with help of specialized proteins, chaperones © 2019 McGraw-Hill Education  2.8b Amino Acid Sequence and 114 Protein Conformation 3 Intramolecular interactions Hydrophobic interactions with nonpolar amino acids farther from water Hydrogen bonds between polar R groups, between amine and carboxylic acid groups Ionic bonds between negative and positive R groups Disulfide bonds between cysteine amino acids © 2019 McGraw-Hill Education  2.8b Amino Acid Sequence and 115 Protein Conformation 4 Secondary structures Patterns that may repeat several times Confer unique characteristics Two types Alpha helix—spiral coil Elasticity to fibrous proteins (e.g., skin and hair) Beta sheet—planar Figure © 2019 McGraw-Hill Education pleat arrangement 2.26b  2.8b Amino Acid Sequence and 116 Protein Conformation 5 Tertiary structure Three- dimensional shape of poly- peptide chain Two categories Globular proteins fold into compact shape Figure © 2019 McGraw-Hill Education Fibrous 2.26c  2.8b Amino Acid Sequence and 117 Protein Conformation 6 Quaternary structure Present in proteins with two or more polypeptide chains E.g., hemoglobin with its four polypeptide chains Figure © 2019 McGraw-Hill Education 2.26d  2.8b Amino Acid Sequence and 118 Protein Conformation 7 Prosthetic groups Nonprotein structures covalently bonded to protein E.g., lipid heme group in hemoglobin protein Denaturation Conformational change to a protein Disturbs protein activity Usually irreversible (boil an egg) May occur due to increased temperature or in © 2019 McGraw-Hill Education  2.8b Amino Acid Sequence and 119 Protein Conformation 8 Other causes of denaturation pH changes Interfere with electrostatic interactions and some other intramolecular bonds Changes in blood pH can be lethal Figure 2.26d © 2019 McGraw-Hill Education  Section 2.8 What did you 120 learn? 39.What distinguishes the tertiary and quaternary levels of organization of a protein? 40.What happens to a protein when it denatures? How does a protein denature when it is exposed to higher than normal H concentration? © 2019 McGraw-Hill Education