2 The Chemistry of Living Things PowerPoint Lecture Slide Presentation Robert J. Sullivan, Marist College Michael D. Johnson Human Biology Concepts and Current Issues THIRD EDITION Copyright 2006 Pearson Education, Inc., publishing as Benjamin Cummings. All Matter Consists of Elements Made of Atoms Atoms, the smallest functional unit, consist of: Protons: positive charge, have mass Neutrons: no charge, have mass Electrons: negative charge, have no discernable mass Radioisotopes Are unstable (varies with isotope) Emit energy (radiation) Emit particles Atoms Combine to Form Molecules Joining atoms requires energy Energy is the capacity to do work Stored energy = potential energy Energy in motion, doing work = kinetic energy Electrons have potential energy Shells = the energy levels of electrons Orbitals describe the probable location of an electron 1
Three Types of Chemical Bonds Covalent Bonds animation Ionic Bonds animation Table 2.1 Elements of Living Organisms Life Depends on Water Water molecules are polar Water is liquid at body temperature Water can absorb and hold heat energy Table 2.2 Two Important Biological Functions of Water Water Keeps Ions in Solution Water is the biological solvent Water helps regulate body temperature Figure 2.9 2
The Importance of Hydrogen Ions Acids are proton (hydrogen ion) donors, bases accept hydrogen ions The ph ScaleThe Organic Molecules of Living Organisms ph Scale = hydrogen ion concentration Buffers: minimize ph change Carbonic acid and bicarbonate act as one of body s most important buffer pairs Figure 2.11 Carbon, the building block of living things: Carbon Can Bond in Many Ways Comprises 18% of body by weight Forms four covalent bonds Can form single or double bonds Can build micro- or macromolecules Figure 2.13 Making and Breaking Biological Macromolecules: Dehydration Synthesis and Hydrolysis Dehydration Synthesis is the Reverse of Hydrolysis Dehydration synthesis Removes equivalent of a water molecule to link molecular units Requires energy Hydrolysis Adds the equivalent of a water molecule to break apart macromolecules Releases energy Figure 2.14 3
4 Macromolecules of Life Carbohydrates Proteins Lipids Nucleic Acids Carbohydrates Monosaccharides Single sugar units Disaccharides Double sugar units Oligosaccharides Multiple sugar units Polysaccharides Starch Glycogen cellulose Carbohydrates are Composed of Monosaccharides Figure 2.15 Carbohydrates are Used for Energy and Structural Support Oligosaccharides: short chains of monosaccharides Disaccharides: sucrose, fructose, lactose Carbohydrates are Used for Energy and Structural Support Polysaccharides: thousands of monosaccarides joined in chains and branches Starch: made in plants; stores energy Glycogen: made in animals; stores energy Cellulose: indigestible polysaccharide made in plants for structural support Disaccharides animation Polysaccharides animation 4
Proteins 4 structural levels of Assembly Primary Secondary Tertiary Quartenary Proteins: Complex Structures Constructed of Amino Acids Structure Introduction to Protein Structure animation Primary: amino acid sequence Chemistry of Life Proteins: Primary Structure animation Secondary: describes chain s orientation in space, e.g., alpha helix, beta sheet Chemistry of Life Proteins: Secondary Structure animation Proteins: Complex Structures Constructed of Amino Acids Tertiary: describes three-dimensional shape created by disulfide and hydrogen bonds Creates polar and nonpolar areas in molecule Chemistry of Life Proteins: Tertiary Structure animation Quaternary: describes proteins in which two or more tertiary protein chains are associated Chemistry of Life Proteins: Quaternary Structure animation 5
Enzyme Function Enzymes: are proteins function as catalysts facilitate chemical reactions Enzyme Function The functional shape of an enzyme is dependent on: temperature of reaction medium ph ion concentration presence of inhibitors Chemistry of Life Proteins: Enzyme animation Lipids: Insoluble in Water Triglycerides: energy storage molecules Fatty acids: saturated and unsaturated Phospholipids: cell membranes Steroids: carbon-based ring structures Cholesterol: used in making estrogen and testosterone Fats animation Structure and Function of Nucleic Acids Functions Store genetic information Provide information used in making proteins Structure Nucleotides consist of a phosphate group, a sugar, and a nitrogenous base DNA structure is a double helix: two associated strands of nucleic acids RNA is a single-stranded molecule Structure of DNA and RNA DNA: double-stranded Sugar: deoxyribose Nitrogenous bases: adenine, thymine, cytosine, guanine Pairing: adenine-thymine and cytosine-guanine RNA: single-stranded Sugar: ribose Nitrogenous bases: adenine, uracil, cytosine, guanine Pairing: adenine-uracil, cytosine-guanine Structure and Function of Adenosine Triphosphate (ATP) Figure 2.26 6
Lecture Review Outline Chapter 2 Chemistry Definitions Importance of Water ph Scale Bonds Macromolecules of Life Carbohydrates Lipids Proteins Nucleic acids 7