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Human Biology

Human Biology. Chapter 2 Chemistry of living things Atoms/Elements Bonds Water pH Molecules of life Carbohydrates *Proteins Lipids *Nucleic Acids. All Matter Consists of Elements Made of Atoms. Chemistry The study of matter Atoms, the smallest functional unit, consist of

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Human Biology

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  1. Human Biology • Chapter 2 • Chemistry of living things • Atoms/Elements • Bonds • Water • pH • Molecules of life • Carbohydrates *Proteins • Lipids *Nucleic Acids

  2. 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

  3. 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

  4. Three Types of Chemical Bonds Table 2.1

  5. Elements of Living Organisms Table 2.2

  6. Life Depends on Water • Water molecules are polar • Water is liquid at body temperature • Water can absorb and hold heat energy

  7. Water Keeps Ions in Solution Figure 2.8

  8. 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

  9. The pH Scale Figure 2.10

  10. 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

  11. Carbon Can Bond in Many Ways Figure 2.12

  12. Making and Breaking Biological Macromolecules: Dehydration Synthesis and Hydrolysis Figure 2.13

  13. 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

  14. Carbohydrates are Composed of Monosaccharides Figure 2.14

  15. Carbohydrates are Used for Energy and Structural Support • Oligosaccharides • Short chains of monosaccharides • Disaccharides • Sucrose, fructose, lactose

  16. 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

  17. 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 Animation—Lipid Structure and Function

  18. 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)

  19. 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

  20. 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

  21. Enzyme Function • Enzymes • Are proteins • Function as catalysts • Speed up chemical reactions • Are not altered or consumed by the reaction

  22. Enzyme Function • The functional shape of an enzyme is dependent on • Temperature of reaction medium • pH • Ion concentration • Presence of inhibitors

  23. 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

  24. Structure of DNA • DNA • Deoxyribonucleic acid • Double–stranded • Sugar • Deoxyribose

  25. Structure of DNA • DNA • Nitrogenous bases • Adenine • Thymine • Cytosine • Guanine • Pairing • Adenine–thymine • Cytosine–guanine

  26. Structure of RNA • RNA • Ribonucleic acid • Single–stranded • Sugar • Ribose

  27. Structure of RNA • RNA • Nitrogenous bases • Adenine • Uracil • Cytosine • Guanine • Pairing • Adenine–uracil • Cytosine–guanine

  28. 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

  29. Structure and Function of Adenosine Triphosphate (ATP) Figure 2.26

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