Chapter 2

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(1)Chapter 2 Chemical Principles. Copyright © 2010 Pearson Education, Inc.. Lectures prepared by.

(2) Q&A  A Salmonella bacterium releases a regulatory molecule containing amino acids and phosphate that causes a human cell’s cytoskeleton to change shape, thereby allowing the bacterium to enter the cell. What type of chemical is this regulatory molecule?. Copyright © 2010 Pearson Education, Inc..

(3) The Structure of Atoms Learning Objectives 2-1 Describe the structure of an atom and its relation to the physical properties of elements.. Copyright © 2010 Pearson Education, Inc..

(4) The Structure of Atoms  Chemistry is the study of interactions between atoms and molecules  The atom is the smallest unit of matter that enters into chemical reactions  Atoms interact to form molecules. Copyright © 2010 Pearson Education, Inc..

(5) The Structure of Atoms  Atoms are composed of  Electrons: Negatively charged particles  Protons: Positively charged particles  Neutrons: Uncharged particles. Copyright © 2010 Pearson Education, Inc..

(6) The Structure of Atoms  Protons and neutrons are in the nucleus  Electrons move around the nucleus. Copyright © 2010 Pearson Education, Inc.. Figure 2.1.

(7) Chemical Elements  Each chemical element has a different number of protons  Isotopes of an element are atoms with different numbers of neutrons. Isotopes of oxygen:. 16 O 8. Copyright © 2010 Pearson Education, Inc.. 17 O 8. 18 O 8.

(8) The Elements of Life. Copyright © 2010 Pearson Education, Inc.. Table 2.1.

(9) Electronic Configurations  Electrons are arranged in electron shells corresponding to different energy levels. Copyright © 2010 Pearson Education, Inc..

(10) Electronic Configurations. Copyright © 2010 Pearson Education, Inc.. Table 2.2.

(11) Electronic Configurations. Copyright © 2010 Pearson Education, Inc.. Table 2.2.

(12) Check Your Understanding  How does 146 C differ from 126 C? What is the atomic number of each carbon atom? The atomic weight? 2-1 €. Copyright © 2010 Pearson Education, Inc.. €.

(13) How Atoms Form Molecules Learning Objectives 2-2 Define ionic bond, covalent bond, hydrogen bond, molecular weight, and mole.. Copyright © 2010 Pearson Education, Inc..

(14) How Atoms Form Molecules  Atoms combine to complete the outermost shell  The number of missing or extra electrons in this shell is known as the valence  Molecules hold together because the valence electrons of the combining atoms form attractive forces, called chemical bonds, between the atomic nuclei. Copyright © 2010 Pearson Education, Inc..

(15) Chemical Bonds  A compound contains different kinds of atoms H2O. Copyright © 2010 Pearson Education, Inc..

(16) Ionic Bonds  The number of protons and electrons is equal in an atom  Ions are charged atoms that have gained or lost electrons. Copyright © 2010 Pearson Education, Inc..

(17) Ionic Bonds. Copyright © 2010 Pearson Education, Inc.. Figure 2.2a.

(18) Ionic Bonds  Ionic bonds are attractions between ions of opposite charge. One atom loses electrons, and another gains electrons.. Copyright © 2010 Pearson Education, Inc..

(19) Ionic Bonds. Copyright © 2010 Pearson Education, Inc.. Figure 2.2b.

(20) Covalent Bonds  Covalent bonds form when two atoms share one or more pairs of electrons. Copyright © 2010 Pearson Education, Inc.. Figure 2.3a.

(21) Covalent Bonds. Copyright © 2010 Pearson Education, Inc.. Figure 2.3b.

(22) Hydrogen Bonds  Hydrogen bonds form when a hydrogen atom that is covalently bonded to an O or N atom is attracted to another N or O atom in another molecule. Copyright © 2010 Pearson Education, Inc.. Figure 2.4.

(23) Molecular Weight and Moles  The sum of the atomic weights in a molecule is the molecular weight  One mole of a substance is its molecular weight in grams. H2O 2H. =21. O. = 16. MW. = 18. 1 mole weighs. Copyright © 2010 Pearson Education, Inc.. = 2. 18g.

(24) Check Your Understanding  Differentiate an ionic bond from a covalent bond. 22. Copyright © 2010 Pearson Education, Inc..

(25) Chemical Reactions Learning Objectives 2-3 Diagram three basic types of chemical reactions.. Copyright © 2010 Pearson Education, Inc..

(26) Chemical Reactions  Chemical reactions involve the making or breaking of bonds between atoms  A change in chemical energy occurs during a chemical reaction  Endergonic reactions absorb energy  Exergonic reactions release energy. Copyright © 2010 Pearson Education, Inc..

(27) Synthesis Reactions  Occur when atoms, ions, or molecules combine to form new, larger molecules. A Atom, ion, or molecule A. +. B Atom, ion, or molecule B. Combines to form. . AB. New molecule AB.  Anabolism is the synthesis of molecules in a cell. Copyright © 2010 Pearson Education, Inc..

(28) Decomposition Reactions  Occur when a molecule is split into smaller molecules, ions, or atoms. AB New molecule AB. Breaks down into. . A Atom, ion, or molecule A. +. B Atom, ion, or molecule B.  Catabolism is the decomposition reactions in a cell. Copyright © 2010 Pearson Education, Inc..

(29) Exchange Reactions  Are part synthesis and part decomposition. NaOH +. Copyright © 2010 Pearson Education, Inc.. HCl.  NaCl. +. H2O.

(30) Reversible Reactions  Can readily go in either direction  Each direction may need special conditions. Heat. A. + B.  AB . Water. Copyright © 2010 Pearson Education, Inc..

(31) Check Your Understanding  This chemical reaction below is used to remove chlorine from water. HClO + Na2SO3  Na2SO4 + HCl.  What type of reaction is it? 2-3. Copyright © 2010 Pearson Education, Inc..

(32) Important Biological Molecules  Organic compounds always contain carbon and hydrogen  Inorganic compounds typically lack carbon. Copyright © 2010 Pearson Education, Inc..

(33) Inorganic Compounds Learning Objectives 2-4 List several properties of water that are important to living systems. 2-5 Define acid, base, salt, and pH.. Copyright © 2010 Pearson Education, Inc..

(34) Water  Inorganic  Polar molecule  Solvent  Polar substances dissociate,forming solutes. Copyright © 2010 Pearson Education, Inc.. Figure 2.4a.

(35) Water. Copyright © 2010 Pearson Education, Inc.. Figure 2.5.

(36) Water  H+ and OH participate in chemical reactions R—R + H2O  R—OH + H—R Maltose + H2O  Glucose + Glucose. Copyright © 2010 Pearson Education, Inc..

(37) Water Maltose + H2O  Glucose + Glucose Glucose. C6H12O6. Glucose. +C6H12O6. Total. C12H24O12. Maltose. C12H22O11. The difference is: Copyright © 2010 Pearson Education, Inc..

(38) Water  H bonds absorb heat  Makes water a temperature buffer. Copyright © 2010 Pearson Education, Inc.. Figure 2.4b.

(39) Acids, Bases, and Salts. Copyright © 2010 Pearson Education, Inc.. Figure 2.6.

(40) Acids  Substances that dissociate into one or more H+ HCl  H+ + Cl. Copyright © 2010 Pearson Education, Inc.. Figure 2.6a.

(41) Bases  Substances that dissociate into one or more OH. NaOH  Na+ + OH. Copyright © 2010 Pearson Education, Inc.. Figure 2.6b.

(42) Salts  Substances that dissociate into cations and anions, neither of which is H+ or OH. NaCl  Na+ + Cl. Copyright © 2010 Pearson Education, Inc.. Figure 2.6c.

(43) Acid-Base Balance     . The amount of H+ in a solution is expressed as pH pH = log[H+] Increasing [H+], increases acidity Increasing [OH] increases alkalinity Most organisms grow best between pH 6.5 and 8.5. Copyright © 2010 Pearson Education, Inc..

(44) The pH Scale. Copyright © 2010 Pearson Education, Inc.. Figure 2.7.

(45) Check Your Understanding  Why is the polarity of a water molecule important? 2-4  Antacids neutralize acid by the following reaction. Mg(OH)2 + 2HCl  MgCl2 + H2O Identify the acid, base, and salt. 2-5. Copyright © 2010 Pearson Education, Inc..

(46) Organic Compounds Learning Objectives 2-6 Distinguish organic and inorganic compounds. 2-7 Define functional group.. Copyright © 2010 Pearson Education, Inc..

(47) Structure and Chemistry  The chain of carbon atoms in an organic molecule is the carbon skeleton. Copyright © 2010 Pearson Education, Inc..

(48) Structure and Chemistry  Functional groups are responsible for most of the chemical properties of a particular organic compound.. Copyright © 2010 Pearson Education, Inc..

(49) Functional Groups. Copyright © 2010 Pearson Education, Inc.. Table 2.3.

(50) Functional Groups. Copyright © 2010 Pearson Education, Inc.. Table 2.3.

(51) Functional Groups  Identify the functional groups in an amino acid:. Copyright © 2010 Pearson Education, Inc..

(52) Check Your Understanding  Define organic. 2-6  Add the appropriate functional group(s) to the ethyl group below to produce each of the following compounds: ethanol, acetic acid, acetaldehyde, ethanolamine, diethyl ether. 2-7. Copyright © 2010 Pearson Education, Inc..

(53) Organic Compounds Learning Objectives 2-8 Identify the building blocks of carbohydrates. 2-9 Differentiate simple lipids, complex lipids, and steroids. 2-10 Identify the building blocks and structure of proteins. 2-11 Identify the building blocks of nucleic acids. 2-12 Describe the role of ATP in cellular activities.. Copyright © 2010 Pearson Education, Inc..

(54) Organic Compounds  Small organic molecules can combine into large macromolecules  Macromolecules are polymers consisting of many small repeating molecules  The smaller molecules are called monomers. Copyright © 2010 Pearson Education, Inc..

(55) Polymers  Monomers join by dehydration synthesis or condensation reactions. Copyright © 2010 Pearson Education, Inc..

(56) Carbohydrates  Cell structures and energy sources  Consist of C, H, and O with the formula (CH2O)n  Monosaccharides are simple sugars with 3 to 7 carbon atoms. Copyright © 2010 Pearson Education, Inc..

(57) Carbohydrates  Disaccharides are formed when 2 monosaccharides are joined in a dehydration synthesis  Disaccharides can be broken down by hydrolysis. Copyright © 2010 Pearson Education, Inc..

(58) Dehydration Synthesis and Hydrololysis. Copyright © 2010 Pearson Education, Inc.. Figure 2.8.

(59) Carbohydrates  Oligosaccharides consist of 2 to 20 monosaccharides  Polysaccharides consist of tens or hundreds of monosaccharides joined through dehydration synthesis  Starch, glycogen, dextran, and cellulose are polymers of glucose that are covalently bonded differently  Chitin is a polymer of 2 sugars repeating many times. Copyright © 2010 Pearson Education, Inc..

(60) Check Your Understanding  Give an example of a monosaccharide, a disaccharide, and a polysaccharide. 2-8. Copyright © 2010 Pearson Education, Inc..

(61) Lipids  Primary components of cell membranes  Consist of C, H, and O  Are nonpolar and insoluble in water. Copyright © 2010 Pearson Education, Inc..

(62) Simple Lipids  Fats or triglycerides  Contain glycerol and fatty acids; formed by dehydration synthesis. Copyright © 2010 Pearson Education, Inc..

(63) Structural Formulas of Simple Lipids. Copyright © 2010 Pearson Education, Inc.. Figure 2.9c.

(64) Simple Lipids  Saturated fat: No double bonds  Unsaturated fat: One or more double bonds in the fatty acids  cis: H atoms on the same side of the double bond  trans: H atoms on opposite sides of the double bond. Copyright © 2010 Pearson Education, Inc..

(65) Simple Lipids. Copyright © 2010 Pearson Education, Inc.. Figure 2.9c.

(66) Complex Lipids  Contain C, H, and O + P, N, or S  Membranes are made of phospholipids. Copyright © 2010 Pearson Education, Inc.. Figure 2.10a.

(67) Steroids  4 carbon rings with an –OH group attached to one ring  Part of membranes. Copyright © 2010 Pearson Education, Inc.. Figure 2.11.

(68) Check Your Understanding  How do simple lipids differ from complex lipids? 2-9. Copyright © 2010 Pearson Education, Inc..

(69) Proteins  Are essential in cell structure and function  Enzymes are proteins that speed chemical reactions  Transporter proteins move chemicals across membranes  Flagella are made of proteins  Some bacterial toxins are proteins. Copyright © 2010 Pearson Education, Inc..

(70) Amino Acids  Proteins consist of subunits called amino acids. Copyright © 2010 Pearson Education, Inc.. Figure 2.12.

(71) Amino Acids  Exist in either of two stereoisomers: D or L.  L-forms are most often found in nature.. Copyright © 2010 Pearson Education, Inc..

(72) Amino Acids. Copyright © 2010 Pearson Education, Inc.. Figure 2.13.

(73) Peptide Bonds  Peptide bonds between amino acids are formed by dehydration synthesis. Copyright © 2010 Pearson Education, Inc.. Figure 2.14.

(74) Levels of Protein Structure  The primary structure is a polypeptide chain. Copyright © 2010 Pearson Education, Inc.. Figure 2.15a.

(75) Levels of Protein Structure  The secondary structure occurs when the amino acid chain folds and coils in a regular helix or pleats. Copyright © 2010 Pearson Education, Inc.. Figure 2.15b.

(76) Levels of Protein Structure  The tertiary structure occurs when the helix folds irregularly, forming disulfide bonds, hydrogen bonds, and ionic bonds between amino acids in the chain. Copyright © 2010 Pearson Education, Inc..

(77) Levels of Protein Structure. Copyright © 2010 Pearson Education, Inc.. Figure 2.15c.

(78) Levels of Protein Structure  The quaternary structure consists of 2 or more polypeptides.. Copyright © 2010 Pearson Education, Inc.. Figure 2.15d.

(79) Protein Structure. Copyright © 2010 Pearson Education, Inc.. Figure 2.15.

(80) Levels of Protein Structure  Conjugated proteins consist of amino acids and other organic molecules  Glycoproteins  Nucleoproteins  Lipoproteins. Copyright © 2010 Pearson Education, Inc..

(81) Q&A  A Salmonella bacterium releases a regulatory molecule containing amino acids and phosphate that causes a human cell’s cytoskeleton to change shape, thereby allowing the bacterium to enter the cell. What type of chemical is this regulatory molecule? Copyright © 2010 Pearson Education, Inc..

(82) Check Your Understanding  What two functional groups are in all amino acids? 2-10. Copyright © 2010 Pearson Education, Inc..

(83) Nucleic Acids  Consist of nucleotides  Nucleotides consist of a  Pentose  Phosphate group  Nitrogen-containing (purine or pyrimidine) base.  Nucleosides consist of a  Pentose  Nitrogen-containing base. Copyright © 2010 Pearson Education, Inc..

(84) Nucleic Acids. Copyright © 2010 Pearson Education, Inc.. Figure 2.16.

(85) DNA     . Deoxyribonucleic acid Has deoxyribose Exists as a double helix A hydrogen bonds with T C hydrogen bonds with G. Copyright © 2010 Pearson Education, Inc..

(86) DNA. Copyright © 2010 Pearson Education, Inc.. Figure 2.16.

(87) RNA     . Ribonucleic acid Has ribose Is single-stranded A hydrogen bonds with U C hydrogen bonds with G. Copyright © 2010 Pearson Education, Inc..

(88) RNA. Copyright © 2010 Pearson Education, Inc.. Figure 2.17.

(89) ATP  Adenosine triphosphate  Has ribose, adenine, and 3 phosphate groups.. Copyright © 2010 Pearson Education, Inc..

(90) The Structure of ATP. Copyright © 2010 Pearson Education, Inc.. Figure 2.18.

(91) ATP  Is made by dehydration synthesis  Is broken by hydrolysis to liberate useful energy for the cell. Copyright © 2010 Pearson Education, Inc..

(92) Check Your Understanding  Which can provide more energy for a cell and why: ATP or ADP? 2-12. Copyright © 2010 Pearson Education, Inc..

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