Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Human Anatomy & Physiology, Sixth Edition Elaine N. Marieb PowerPoint ® Lecture Slides prepared by Vince Austin, University of Kentucky 2 Chemistry Comes Alive Part B

Copyright © 2004 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 © 2004 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 © 2004 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 InterActive Physiology ® : Fluid, Electrolyte, and Acid/Base Balance: Introduction to Body Fluids PLAY

Copyright © 2004 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 © 2004 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 © 2004 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 © 2004 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 Figure 2.12

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 InterActive Physiology ® : Fluid, Electrolyte, and Acid/Base Balance: Acid/Base Homeostasis PLAY

Copyright © 2004 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 © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Figure 2.13a  Contain carbon, hydrogen, and oxygen  Their major function is to supply a source of cellular food  Examples:  Monosaccharides or simple sugars

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Figure 2.13b  Disaccharides or double sugars

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Carbohydrates Figure 2.13c  Polysaccharides or polymers of simple sugars

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Neutral Fats (Triglycerides) Figure 2.14a  Composed of three fatty acids bonded to a glycerol molecule

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Other Lipids Figure 2.14b  Phospholipids – modified triglycerides with two fatty acid groups and a phosphorus group

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Other Lipids Figure 2.14c  Steroids – flat molecules with four interlocking hydrocarbon rings  Eicosanoids – 20-carbon fatty acids found in cell membranes

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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  Fat-soluble vitamins – vitamins A, E, and K  Eicosanoids – prostaglandins, leukotriens, and thromboxanes  Lipoproteins – transport fatty acids and cholesterol in the bloodstream

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids  Building blocks of protein, containing an amino group and a carboxyl group  Amino acid structure InterActive Physiology ® : Fluid, Electrolyte, and Acid/Base Balance: Introduction to Body Fluids PLAY

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids Figure 2.15a-c

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Amino Acids Figure 2.15d, e

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Figure 2.16  Macromolecules composed of combinations of 20 types of amino acids bound together with peptide bonds

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins  Primary – amino acid sequence  Secondary – alpha helices or beta pleated sheets Chemistry of Life: Proteins: Secondary Structure PLAY

Copyright © 2004 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 Chemistry of Life: Proteins: Quaternary Structure PLAY Chemistry of Life: Proteins: Tertiary Structure PLAY

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins Figure 2.17a-c

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structural Levels of Proteins Figure 2.17d, e

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fibrous and Globular Proteins  Fibrous proteins  Extended and strandlike 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 © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Denuaturation Figure 2.18a  Reversible unfolding of proteins due to drops in pH and/or increased temperature

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Protein Denuaturation Figure 2.18b  Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 © 2004 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 © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Characteristics of Enzymes Figure 2.19

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Mechanism of Enzyme Action  Enzyme binds with substrate  Product is formed at a lower activation energy  Product is released How Enzymes Work PLAY

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Enzyme- substrate complex (E–S) Internal rearrangements leading to catalysis Free enzyme (E) Active site Enzyme (E) Substrates (s) Amino acids H20H20 Peptide bond Dipeptide product (P) Mechanism of Enzyme Action Figure 2.20

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 © 2004 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 © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structure of DNA Figure 2.21a

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Structure of DNA Figure 2.21b

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 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 © 2004 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 © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Adenosine Triphosphate (ATP) Figure 2.22

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings How ATP Drives Cellular Work Figure 2.23