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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
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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
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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
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Copyright © 2009 Pearson Education, Inc. Three Types of Chemical Bonds Table 2.1
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Copyright © 2009 Pearson Education, Inc. Elements of Living Organisms Table 2.2
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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
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Copyright © 2009 Pearson Education, Inc. Water Keeps Ions in Solution Figure 2.8
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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
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Copyright © 2009 Pearson Education, Inc. The pH Scale Figure 2.10
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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
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Copyright © 2009 Pearson Education, Inc. Carbon Can Bond in Many Ways Figure 2.12
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Copyright © 2009 Pearson Education, Inc. Making and Breaking Biological Macromolecules: Dehydration Synthesis and Hydrolysis Figure 2.13
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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
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Copyright © 2009 Pearson Education, Inc. Figure 2.14 Carbohydrates are Composed of Monosaccharides
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Copyright © 2009 Pearson Education, Inc. Carbohydrates are Used for Energy and Structural Support Oligosaccharides Short chains of monosaccharides Disaccharides Sucrose, fructose, lactose
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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
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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
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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)
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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
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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
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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
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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
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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
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Copyright © 2009 Pearson Education, Inc. Structure of DNA DNA Deoxyribonucleic acid Double–stranded Sugar Deoxyribose
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Copyright © 2009 Pearson Education, Inc. Structure of DNA DNA Nitrogenous bases Adenine Thymine Cytosine Guanine Pairing Adenine–thymine Cytosine–guanine
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Copyright © 2009 Pearson Education, Inc. Structure of RNA RNA Ribonucleic acid Single–stranded Sugar Ribose
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Copyright © 2009 Pearson Education, Inc. Structure of RNA RNA Nitrogenous bases Adenine Uracil Cytosine Guanine Pairing Adenine–uracil Cytosine–guanine
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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
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Copyright © 2009 Pearson Education, Inc. Structure and Function of Adenosine Triphosphate (ATP) Figure 2.26
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