1. Foundations in Microbiology Seventh Edition
Lecture PowerPoint to accompany
Foundations in Microbiology Seventh Edition
Talaro
Chapter 2
The Chemistry of Biology
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2. 2.1 Atoms, Bonds, and Molecules
Matter - all materials that occupy space and have mass
Matter is composed of atoms
Atom - simplest form of matter not divisible into simpler substances
Protons: (+) subatomic particles
Neutrons: neutral subatomic particles
Electrons: (-) subatomic particles

3. Figure 2.1a Three-dimensional model

4. Figure 2.1b Simple model

5. Different Types of Atoms
All atoms share the same fundamental structure
Element - pure substances with a characteristic number of protons, neutrons, and electrons and predictable chemical behaviors

6. Table 2.1 The Major Elements of Life

7. Characteristics of Elements
Atomic number – number of protons
Mass number – number of protons and neutrons
Isotopes – variant forms of the same element that differ in the number of neutrons
Atomic weight – average mass numbers of all isotopic forms
Electron orbitals – volumes of space surrounding the atomic nucleus where electrons are likely to be found

8. Figure 2.1 Models of atomic structure

9. Figure 2.2 Biologically important atoms

10. Bonds and Molecules
Molecule - a chemical substance that results from the combination of two or more atoms
Compounds - molecules that are combinations of two or more different elements
Formula/Mass weight - sum of all of the atomic masses of the atoms a molecule contains
Chemical bonds - when 2 or more atoms share, donate, or accept electrons to form molecules and compounds
3 types: covalent, ionic, and hydrogen

11. 3 Types of Chemical Bonds
Covalent bonds – electrons are shared among atoms
Polar covalent bonds – unequal sharing
Nonpolar covalent bonds – equal sharing
Ionic bonds – electrons are transferred to one atom forming positively charged cations and negatively charged anions
Hydrogen bonds – weak bonds between hydrogen and other atoms

12. Figure 2.3 Three types of bonds

13. Figure 2.4 Covalent bonds

14. Figure 2.5 Polar molecule

15. Figure 2.6 Ionic bonding

16. Figure 2.7 Ionization

17. Figure 2.8 Hydrogen bonding

18. Electron Transfer and Oxidation-Reduction Reactions
Energy exchange in cells is a result of the
movement of electrons from one molecule to
another.
Oxidation – the loss of electrons
Reduction – the gaining of electrons
Redox reactions – essential to biochemical processes

19. Figure 2.9 Oxidation-reduction reaction

20. Chemical Shorthand Reactants - molecules starting a reaction
Products - substances left by a reaction
Synthesis reaction - the reactants bond together in a manner that produces an entirely new molecule S + O2
SO2

21. Figure 2.10 Molecular and Structural Formulas

22. Solutions: Mixtures of Molecules
Solution – a mixture of one or more substances called solutes, dispersed in a dissolving medium called a solvent
Solutes – Na+ & Cl-
Solvent – H2O

23. Most biological activities occur in aqueous (water-based) solutions
Hydrophilic molecules - dissolve in water
Hydrophobic molecules - repel water
Amphipathic molecules - have both hydrophilic and hydrophobic properties

24. Figure 2.12 Hydration spheres formed around ions

25. Acidity, Alkalinity, and the pH Scale
Ionization of H2O releases hydrogen ions [H+] and hydroxyl ions [OH-]
pH scale – ranges from 0 to 14, expresses the concentration of H+ ions
pH is the negative logarithm of the concentration of H+ ions.
pH 2 = 0.01 moles/L H+ ions
pH 14 = moles/L H+ ions

26. Figure 2.13 The pH scale

27. Table 2.2

28. The Chemistry of Carbon and Organic Compounds
Organic chemicals – compounds containing carbon bonded to hydrogens

29. Carbon is the fundamental element of life
Contains 4 atoms in its outer orbital
Can form single, double, or triple covalent bonds
Can form linear, branched, or ringed molecules

30. Figure 2.14 The versatility of bonding in carbon

31. Functional Groups of Organic Compounds
Accessory molecules that bind to organic compounds
Confer unique reactive properties on the whole molecule

32. 2.2 Macromolecules
Biochemicals are organic compounds produced by living things
Macromolecules: large compounds assembled from smaller subunits
Monomer: a repeating subunit
Polymer: a chain of monomers

33. Macromolecules
Carbohydrates – monosaccharides, disaccharides, polysaccharides
Lipids – triglycerides (fats and oils), phospholipids, steroids
Proteins
Nucleic acids – DNA, RNA

34. Carbohydrates Sugars and polysaccharides
General formula (CH2O)n
Aldehydes and ketones
Saccharide: simple carbohydrate
Monosaccharide: 3-7 carbons
Disaccharide: two monosaccharides
Polysaccharide: five or more monosaccharides

35. Figure 2.15a Common classes of carbohydrates

36. Figure 2.15b Common classes of carbohydrates

37. Carbohydrates Subunits linked by glycosidic bonds
Dehydration synthesis: loss of water in a polymerization reaction

38. Carbohydrates
Functions – cell structure, adhesion, and metabolism

39. Lipids Long or complex, hydrophobic, C - H chains
Triglycerides, phospholipids in membranes, steroids like cholesterol
Functions
Triglycerides – energy storage
Phospholipid – major cell membrane component
Steroids – cell membrane component

40. Figure 2.18b Triglycerides

41. Figure 2.19 Phospholipids - membrane molecules

42. Figure 2.20 Membrane

43. Proteins Predominant molecules in cells Monomer – amino acids – 20
Polymer – peptide, polypeptide, protein
Subunits linked by peptide bonds
Fold into very specific 3-D shapes
Functions – support, enzymes, transport, defense, movement

45. Figure 2.21 Formation of a peptide bond

47. Nucleic Acids DNA and RNA Monomer – nucleotide
DNA – deoxyribonucleic acid
A,T,C,G – nitrogen bases
Double helix
Function – hereditary material
RNA – ribonucleic acid
A,U,C,G – nitrogen bases
Function – organize protein synthesis

49. Figure 2.24 Sugars and nitrogen bases of DNA and RNA

50. Double Helix of DNA
DNA is formed by two very long polynucleotide strands linked along their length by hydrogen bonds

51. Passing on the Genetic Message
Each strand is copied
Replication is guided by base pairing
End result is two separate double strands

52. ATP: The Energy Molecule of Cells
Adenosine triphosphate
Nucleotide - adenine, ribose, three phosphates
Function - transfer and storage of energy
Insert figure 2.27 a
ATP molecule