1. PowerPoint ® Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R © 2015 Pearson Education, Inc. The Chemistry of Microbiology 2

2. © 2015 Pearson Education, Inc. Atoms Matter – anything that takes up space and has mass Atoms – the smallest chemical units of matter

3. © 2015 Pearson Education, Inc. Atoms Atomic Structure Electrons – negatively charged subatomic particles circling a nucleus Nucleus – structure containing neutrons and protons Neutrons – uncharged particles Protons – positively charged particles

4. © 2015 Pearson Education, Inc. Electron shells Nucleus Proton (p + ) Neutron (n 0 ) Electron (e – ) Figure 2.1 An example of a Bohr model of atomic structure.

5. © 2015 Pearson Education, Inc. Atoms Atomic Structure Element – composed of a single type of atom Atomic number – equal to the number of protons in the nucleus Atomic mass (atomic weight) – sum of masses of protons, neutrons, and electrons

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7. Atoms Isotopes Atoms of a given element that differ in the number of neutrons in their nuclei Stable isotopes Unstable isotopes Radioactive isotopes Release energy during radioactive decay

8. © 2015 Pearson Education, Inc. Proton Neutron Carbon-12 6 Protons 6 Neutrons Carbon-13 6 Protons 7 Neutrons Carbon-14 6 Protons 8 Neutrons Additional neutron Figure 2.2 Nuclei of the three naturally occurring isotopes of carbon.

9. © 2015 Pearson Education, Inc. Atoms Electron Configurations Only the electrons of atoms interact, so they determine atom's chemical behavior Electrons occupy electron shells Valence electrons – electrons in outermost shell that interact with other atoms

10. © 2015 Pearson Education, Inc. + + = Second shell First shell Electron shells of neon: three-dimensional view + = First shell Second shell Electron shells of neon: two-dimensional view Figure 2.3 Electron configurations.

11. © 2015 Pearson Education, Inc. Figure 2.4 Bohr diagrams of the first 20 elements and their places within the chart known as the periodic table of the elements.

12. © 2015 Pearson Education, Inc. Atoms Tell Me Why Electrons zip around the nucleus at about 5 million miles per hour. Why don't some fly off?

13. © 2015 Pearson Education, Inc. Chemical Bonds Valence – combining capacity of an atom Positive if atom has electrons to give up Negative if atom has spaces to fill Stable when outer electron shells contain eight electrons Chemical bonds – atoms combine by sharing or transferring valence electrons Molecule – two or more atoms held together by chemical bonds Compound – a molecule composed of more than one element

14. © 2015 Pearson Education, Inc. Chemical Bonds Covalent bond – sharing of a pair of electrons by two atoms Electronegativity – attraction of atom for electrons The more electronegative an atom, the greater the pull its nucleus exerts on electrons

15. © 2015 Pearson Education, Inc. Figure 2.6 Electronegativity values of selected elements.

16. © 2015 Pearson Education, Inc. Chemical Bonds Nonpolar Covalent Bonds Shared electrons spend equal amounts of time around each nucleus Atoms with similar electronegativities No poles exist Carbon atoms form four nonpolar covalent bonds with other atoms Organic compounds contain carbon and hydrogen atoms

17. © 2015 Pearson Education, Inc. Figure 2.5a-b Four molecules formed by covalent bonds.

18. © 2015 Pearson Education, Inc. Figure 2.5c-d Four molecules formed by covalent bonds.

19. © 2015 Pearson Education, Inc. Chemical Bonds Polar Covalent Bonds Unequal sharing of electrons due to significantly different electronegativities Most important polar covalent bonds involve hydrogen Allow for hydrogen bonding

20. © 2015 Pearson Education, Inc. Figure 2.7 Polar covalent bonding in a water molecule.

21. © 2015 Pearson Education, Inc. Chemical Bonds Ionic Bonds Occur when two atoms with vastly different electronegativities come together Atoms have either positive (cation) or negative (anion) charges Cations and anions attract each other and form ionic bonds (no electrons shared) Typically form crystalline ionic compounds known as salts

22. © 2015 Pearson Education, Inc. Figure 2.8 The interaction of sodium and chlorine to form an ionic bond.

23. © 2015 Pearson Education, Inc. Figure 2.9 Dissociation of NaCI in water.

24. © 2015 Pearson Education, Inc. Chemical Bonds Hydrogen Bonds Electrical attraction between partially charged H + and full or partial negative charge on same or different molecule Weaker than covalent bonds but essential for life Help to stabilize 3-D shapes of large molecules

25. © 2015 Pearson Education, Inc. Figure 2.10 Hydrogen bonds.

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27. Chemical Bonds Tell Me Why Chlorine and potassium atoms form ionic bonds, carbon atoms form nonpolar covalent bonds with nitrogen atoms, and oxygen forms polar covalent bonds with phosphorus. Explain why these bonds are the types they are.

28. © 2015 Pearson Education, Inc. Chemical Reactions The making or breaking of chemical bonds Involve reactants and products Biochemistry involves chemical reactions of living things

29. © 2015 Pearson Education, Inc. Chemical Reactions Synthesis Reactions Involve the formation of larger, more complex molecules Require energy (endothermic) Common type is dehydration synthesis Water molecule formed All the synthesis reactions in an organism are called anabolism

30. © 2015 Pearson Education, Inc. Figure 2.11a Two types of chemical reactions in living things.

31. © 2015 Pearson Education, Inc. Chemical Reactions Decomposition Reactions Break bonds within larger molecules to form smaller atoms, ions, and molecules Release energy (exothermic) Common type is hydrolysis Ionic components of water are added to products All the decomposition reactions in an organism are called catabolism

32. © 2015 Pearson Education, Inc. Figure 2.11b Two types of chemical reactions in living things.

33. © 2015 Pearson Education, Inc. Chemical Reactions Exchange Reactions Involve breaking and forming covalent bonds Have endothermic and exothermic steps Atoms are moved from one molecule to another Sum of all chemical reactions in an organism is called metabolism

34. © 2015 Pearson Education, Inc. Chemical Reactions Tell Me Why Why are decomposition reactions exothermic (release energy)?

35. © 2015 Pearson Education, Inc. Water, Acids, Bases, and Salts Water Most abundant substance in organisms Many special characteristics due to two polar covalent bonds Cohesive molecules – surface tension Excellent solvent Remains liquid across wide range of temperatures Can absorb significant amounts of energy without changing temperature Participates in many chemical reactions

36. © 2015 Pearson Education, Inc. Aquarius remigis, a water strider Hydrogen bonds Figure 2.12 The cohesiveness of liquid water.

37. © 2015 Pearson Education, Inc. Water, Acids, Bases, and Salts Acids and Bases Dissociated by water into component cations and anions Acid – dissociates into one or more H + and one or more anions Base – binds with H + when dissolved into water; some dissociate into cations and OH – Concentration of H + in solution expressed using the pH scale Metabolism requires relatively constant balance of acids and bases Buffers prevent drastic changes in internal pH Microorganisms differ in their tolerance of various pH ranges Some microbes can change the pH of their environment

38. © 2015 Pearson Education, Inc. Figure 2.13 Acids and bases.

39. © 2015 Pearson Education, Inc. Figure 2.14 The pH scale.

40. © 2015 Pearson Education, Inc. Water, Acids, Bases, and Salts Salts Compounds that dissociate in water into cations and anions other than H + and OH – Cations and anions of salts are electrolytes Create electrical differences between inside and outside of cell Transfer electrons from one location to another Form important components of many enzymes

41. © 2015 Pearson Education, Inc. Water, Acids, Bases, and Salts Tell Me Why Why does the neutralization of an acid by a base often produce water?

42. © 2015 Pearson Education, Inc. Organic Macromolecules Functional Groups Contain carbon and hydrogen atoms Atoms often appear in arrangements called functional groups Macromolecules – large molecules used by all organisms Lipids Carbohydrates Proteins Nucleic acids Monomers – basic building blocks of macromolecules

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44. Organic Macromolecules Lipids Not composed of regular subunits Are all hydrophobic Four groups Fats Phospholipids Waxes Steroids

45. © 2015 Pearson Education, Inc. 3 Dehydration synthesis 3 fatty acids + GlycerolFat (triglyceride) Ester bond Saturated fatty acid Monounsaturated fatty acid Figure 2.15 Fats (triglycerides).

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47. Organic group Phosphate group Glycerol Saturated fatty acid Unsaturated fatty acid Double bond Hydrophilic (polar) head Hydrophobic (nonpolar) tails Symbol Phospholipid bilayer Unsaturated fatty acid Cell Phospholipid Figure 2.16 Phospholipids.

48. © 2015 Pearson Education, Inc. Organic Macromolecules Lipids Waxes Contain one long-chain fatty acid covalently linked to long-chain alcohol by ester bond Lack hydrophilic head Completely insoluble in water

49. © 2015 Pearson Education, Inc. Phospholipids Cholesterol Cell membrane Figure 2.17 Steroids.

50. © 2015 Pearson Education, Inc. Organic Macromolecules Monomers are the basic building blocks of macromolecules Monomers join to form chains called polymers

51. © 2015 Pearson Education, Inc. Organic Macromolecules Carbohydrates Organic molecules composed of carbon, hydrogen, and oxygen (CH 2 O) n Functions Long-term storage of chemical energy Ready energy source Part of backbones of nucleic acids Converted to amino acids Form cell wall Involved in intracellular interactions between animal cells

52. © 2015 Pearson Education, Inc. Organic Macromolecules Carbohydrates Types Monosaccharides Disaccharides Polysaccharides

53. © 2015 Pearson Education, Inc. Glucose α configuration β configuration N-acetylglucosamine Acetyl group Figure 2.18 Monosaccharides (simple sugars).

54. © 2015 Pearson Education, Inc. Figure 2.19 Disaccharides.

55. © 2015 Pearson Education, Inc. α-1,6 bond Hydrogen bonds Hydrogen bond α-1,6 bond Cellulose Amylose (unbranched) β-1,4 bonds α-1,4 bonds α-1,4 bond Glycogen Figure 2.20 Polysaccharides.

56. © 2015 Pearson Education, Inc. Organic Macromolecules Proteins Mostly composed of carbon, hydrogen, oxygen, nitrogen, and sulfur Functions Structure Enzymatic catalysis Regulation Transportation Defense and offense

57. © 2015 Pearson Education, Inc. Organic Macromolecules Proteins Amino acids The monomers that make up proteins Most organisms use only 21 amino acids in protein synthesis Side groups affect how amino acids interact with one another and how a protein interacts with other molecules A covalent peptide bond is formed between amino acids

58. © 2015 Pearson Education, Inc. Figure 2.21 Amino acids.

59. © 2015 Pearson Education, Inc. Figure 2.22 Stereoisomers, molecules that are mirror images of one another.

60. © 2015 Pearson Education, Inc. Carboxyl group Amino group Dehydration synthesis Peptide bond DipeptideAmino acid 2Amino acid 1 Figure 2.23 The linkage of amino acids by peptide bonds via a dehydration reaction.

61. © 2015 Pearson Education, Inc. Peptide bond Primary structure Amino acid 1 Amino acid 2 Amino acid 3 Amino acid 4 α-helix Secondary structure β-pleated sheet Hydrogen bond β-pleated sheets α-helix Tertiary structure Quaternary structure: two or more polypeptides act together as a single protein Figure 2.24 Levels of protein structure.

62. © 2015 Pearson Education, Inc. Organic Macromolecules Nucleic Acids DNA and RNA are the genetic material of organisms and viruses RNA also acts as enzyme, binds amino acids, and helps form polypeptides

63. © 2015 Pearson Education, Inc. Organic Macromolecules Nucleic Acids Nucleotides and nucleosides Nucleotides Monomers that make up nucleic acids Composed of three parts Phosphate Pentose sugar – deoxyribose or ribose One of five cyclic nitrogenous bases Nucleosides are nucleotides lacking phosphate

64. © 2015 Pearson Education, Inc. Phosphate group Purine or pyrimidine nitrogenous base Pentose sugar Deoxyribose Ribose PurinesPyrimidines Adenine (A) (Used in DNA and RNA) Thymine (T) (Used in DNA) Guanine (G) (Used in DNA and RNA) Cytosine (C) (Used in DNA and RNA) Uracil (U) (Used in RNA) Figure 2.25 Nucleotides.

65. © 2015 Pearson Education, Inc. Organic Macromolecules Nucleic Acids Nucleic acid structure Three H bonds form between C and G Two H bonds form between T and A (DNA) or U and A (RNA) DNA is double stranded in most cells and viruses The two strands are complementary The two strands are antiparallel

66. © 2015 Pearson Education, Inc. 5' end Deoxyribose Phosphate Adenine base Guanine base Thymine base Cytosine base Two hydrogen bonds Three hydrogen bonds Sugar- phosphate backbones 5' C 4' 3' 2' 1' 3' end 5' 3' 5' 3' Figure 2.26 General nucleic acid structure.

67. © 2015 Pearson Education, Inc. Organic Macromolecules Nucleic Acids Nucleic acid function DNA is genetic material of all organisms and of many viruses Carries instructions for synthesizing RNA and proteins Controls synthesis of all molecules in an organism

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69. Figure 2.27 ATP.

70. © 2015 Pearson Education, Inc. Organic Macromolecules Tell Me Why Why do the cell membranes of microbes living in Arctic water likely contain more unsaturated fatty acids than do membranes of microbes living in hot springs?