1. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. MICHAEL D. JOHNSON THE CHEMISTRY OF LIVING THINGS CHAPTER 2 THE CHEMISTRY OF LIVING THINGS PowerPoint ® Lecture Slide Presentation by Robert J. Sullivan, Marist College Human Biology Concepts and Current Issues Second Edition

2. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Atoms, the smallest functional unit, consist of: Protons: positive charge, have mass Neutrons: no charge, have mass Electrons: negative charge, have no discernable mass All Matter Consists of Elements Made of Atoms

3. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Same element, same atomic number = same number of protons and electrons Different number of neutrons = different weight Isotopes

4. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Are unstable (varies with isotope) Emit energy (radiation) Emit particles Radioisotopes

5. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. 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 Atoms Combine to Form Molecules

6. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Three Types of Chemical Bonds Table 2.1

7. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Elements of Living Organisms Table 2.2

8. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Water molecules are polar Water is liquid at body temperature Water can absorb and hold heat energy Life Depends on Water

9. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Water is the biological solvent Water helps regulate body temperature Two Important Biological Functions of Water

10. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Water Keeps Ions in Solution Figure 2.9

11. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Acids are proton (hydrogen ion) donors, bases accept hydrogen ions pH Scale = hydrogen ion concentration Buffers: minimize pH change Carbonic acid and bicarbonate act as one of body’s most important buffer pairs The Importance of Hydrogen Ions

12. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. The pH Scale Figure 2.11

13. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Carbon, the building block of living things: Comprises 18% of body by weight Forms four covalent bonds Can form single or double bonds Can build micro- or macromolecules The Organic Molecules of Living Organisms

14. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Carbon Can Bond in Many Ways Figure 2.13

15. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Making and Breaking Biological Macromolecules: Dehydration Synthesis and Hydrolysis Figure 2.14

16. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. 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 Dehydration Synthesis is the Reverse of Hydrolysis

17. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Carbohydrates are Composed of Monosaccharides Figure 2.15

18. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Oligosaccharides: short chains of monosaccharides Disaccharides: sucrose, fructose, lactose Polysaccharides: thousands of monosaccarides joined in chains and branches Starch: made in plants; stores energy Glycogen: made in animals; stores energy Cellulose: undigestible polysaccharide made in plants for structural support Carbohydrates are Used for Energy and Structural Support

19. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Triglycerides: energy storage molecules Fatty acids: saturated and unsaturated Phospholipids: cell membranes Steroids: carbon-based ring structures Cholesterol: used in making estrogen and testosterone Lipids: Insoluble in Water

20. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Structure Primary: amino acid sequence Secondary: describes chain’s orientation in space; e.g., alpha helix, beta sheet Tertiary: describes three-dimensional shape created by disulfide and hydrogen bonds Creates polar and nonpolar areas in molecule Quaternary: describes proteins in which two or more tertiary protein chains are associated Proteins: Complex Structures Constructed of Amino Acids

21. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Enzymes: are proteins function as catalysts facilitate chemical reactions The functional shape of an enzyme is dependent on: temperature of reaction medium pH ion concentration presence of inhibitors Enzyme Function

22. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. 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 and Function of Nucleic Acids

23. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. 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 of DNA and RNA

24. Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings. Structure and Function of Adenosine Triphosphate (ATP) Figure 2.26