Copyright © 2009 Pearson Education, Inc. Human Biology  Chapter 2  Chemistry of living things  Atoms/Elements  Bonds  Water  pH  Molecules of life  Carbohydrates*Proteins  Lipids*Nucleic Acids

Copyright © 2009 Pearson Education, Inc. All Matter Consists of Elements Made of Atoms  Chemistry  The study of matter  Atoms, the smallest functional unit, consist of  Protons: positive charge, have mass  Neutrons: no charge, have mass  Electrons: negative charge, have no discernable mass

Copyright © 2009 Pearson Education, Inc. 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

Copyright © 2009 Pearson Education, Inc. Three Types of Chemical Bonds Table 2.1

Copyright © 2009 Pearson Education, Inc. Elements of Living Organisms Table 2.2

Copyright © 2009 Pearson Education, Inc. Life Depends on Water  Water molecules are polar  Water is liquid at body temperature  Water can absorb and hold heat energy

Copyright © 2009 Pearson Education, Inc. Water Keeps Ions in Solution Figure 2.8

Copyright © 2009 Pearson Education, Inc. The Importance of Hydrogen Ions  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 the body’s most important buffer pairs

Copyright © 2009 Pearson Education, Inc. The pH Scale Figure 2.10

Copyright © 2009 Pearson Education, Inc. The Organic Molecules of Living Organisms Carbon, the building block of living things  Comprises 18% of the body by weight  Forms four covalent bonds  Can form single or double bonds  Can build micro- or macromolecules

Copyright © 2009 Pearson Education, Inc. Carbon Can Bond in Many Ways Figure 2.12

Copyright © 2009 Pearson Education, Inc. Making and Breaking Biological Macromolecules: Dehydration Synthesis and Hydrolysis Figure 2.13

Copyright © 2009 Pearson Education, Inc. 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

Copyright © 2009 Pearson Education, Inc. Figure 2.14 Carbohydrates are Composed of Monosaccharides

Copyright © 2009 Pearson Education, Inc. Carbohydrates are Used for Energy and Structural Support  Oligosaccharides  Short chains of monosaccharides  Disaccharides  Sucrose, fructose, lactose

Copyright © 2009 Pearson Education, Inc. Carbohydrates are Used for Energy and Structural Support  Polysaccharides: thousands of monosaccharides 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

Copyright © 2009 Pearson Education, Inc. Animation—Lipid Structure and Function 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 PLAY

Copyright © 2009 Pearson Education, Inc. Proteins: Complex Structures Constructed of Amino Acids  Structure  Primary: amino acid sequence  Secondary: describes chain’s orientation in space (e.g., alpha helix, beta sheet)

Copyright © 2009 Pearson Education, Inc. 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  Quaternary: describes proteins in which two or more tertiary protein chains are associated

Copyright © 2009 Pearson Education, Inc. Proteins: Complex Structures Constructed of Amino Acids  Denaturation  Permanent disruption of protein structure  Can be damaged by temperature or changes in pH  Leads to loss of biological function

Copyright © 2009 Pearson Education, Inc. Enzyme Function  Enzymes  Are proteins  Function as catalysts  Speed up chemical reactions  Are not altered or consumed by the reaction

Copyright © 2009 Pearson Education, Inc. Enzyme Function  The functional shape of an enzyme is dependent on  Temperature of reaction medium  pH  Ion concentration  Presence of inhibitors

Copyright © 2009 Pearson Education, Inc. 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

Copyright © 2009 Pearson Education, Inc. Structure of DNA  DNA  Deoxyribonucleic acid  Double–stranded  Sugar  Deoxyribose

Copyright © 2009 Pearson Education, Inc. Structure of DNA  DNA  Nitrogenous bases  Adenine  Thymine  Cytosine  Guanine  Pairing  Adenine–thymine  Cytosine–guanine

Copyright © 2009 Pearson Education, Inc. Structure of RNA  RNA  Ribonucleic acid  Single–stranded  Sugar  Ribose

Copyright © 2009 Pearson Education, Inc. Structure of RNA  RNA  Nitrogenous bases  Adenine  Uracil  Cytosine  Guanine  Pairing  Adenine–uracil  Cytosine–guanine

Copyright © 2009 Pearson Education, Inc. Structure and Function of Adenosine Triphosphate (ATP)  Universal energy source  Bonds between phosphate groups contain potential energy  Breaking the bonds releases energy  ATP  ADP + P1 + energy

Copyright © 2009 Pearson Education, Inc. Structure and Function of Adenosine Triphosphate (ATP) Figure 2.26