Chapter 2 The Chemistry of Microbiology

1
Chapter 2 The Chemistry of Microbiology

• Atoms and elements
• Chemical bonds
• Chemical reactions
• Chemical components of the cell
• Carbohydrates
• Proteins
• Nucleic Acids
• Lipids

2
Atoms
3
Elements and Compounds

• A substance that
  consists of a single type of atom
• Elements are identified by
• Also important
• charged atoms
• substance composed of two
  or more different elements

4
Electron Orbitals

• Consider electrons arranged
• Electrons can move between orbitals
• Orbitals contain
• Atoms are most stable if
• Atoms can gain or lose electrons

5
Chemical Bonds Covalent Bonds

• Outer electron
• Covalent bonds may be polar or nonpolar

6
Nonpolar Covalent Bonds
Figure 2.5
7
Polar Covalent Bonds H2O
Figure 2.7a
8
Chemical Bonds Ionic Bonds
1
Electron donated
Na
Cl

• Weaker than
• Electron is stolen by more electronegative atom
• Ionic bonds leave each atom charged
• positively charged atoms
• negatively charged atoms

Sodium atom
Chlorine atom
(a)
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Ionic Bonds
1
Electron donated
Na
Cl
Sodium atom
Chlorine atom
2
Attraction of opposite charges


Na
Cl
Sodium ion (Na)
Chlorine ion (Cl)
(a)
10
Ionic Bonds
1
Electron donated
Na
Cl
Sodium atom
Chlorine atom
2
Attraction of opposite charges


Na
Cl
Sodium ion (Na)
Chlorine ion (Cl)
3
Formation of an ionic bond


Cl
Na
Sodium chloride ion (NaCl)
(a)
11
Ionic Bonds
1
Electron donated
Na
Cl
Sodium ion (Na)
Chlorine ion (Cl)
Sodium atom
Chlorine atom
2
Attraction of opposite charges


Na
Cl
Sodium ion (Na)
Chlorine ion (Cl)
3
Formation of an ionic bond
Sodium chloride crystal
(b)


Cl
Na
Sodium chloride ion (NaCl)
(a)
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Chemical Bonds Hydrogen (H) Bonds

• Occurs between
• Many H-bonds together can be strong

13
Chemical Reactions

• Synthesis reactions
• Decomposition reactions

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Chemical Components of Cells

• Water
• pH
• Small molecules
• Inorganics Na, K, PO43- etc.
• Organics - ATP, amino acids, DNA precursors, etc.
  
• Macromolecules
• Proteins
• Carbohydrates
• Nucleic acids
• Lipids

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Water
(a) Liquid Water
(b) Ice
16
NaCl Dissolving in Water
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Acids and Bases

• In water
• dissociate into H anion
• dissociate into OH- cation

18
pH Potential Hydrogen

• pH indicates
• HOH ? H OH-
• chemical that maintains pH
  7

19
Small Molecules

• K, Na, Mg2, Ca2, Fe2, Cl-, PO43-, SO42-
• ATP, ADP
• Compounds that accumulate during metabolism

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Adenosine Triphosphate (ATP)
Figure 2.27
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Cellular Organization
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Macromolecule Carbohydrates
Glucose
Monomer
N-acetylglucosamine
Fructose
Figure 2.18a
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Disaccharides
Dehydration synthesis of sucrose
Hydrolysis of sucrose
Figure 2.19
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Polysaccharides (Carbohydrates)
Cellulose
Amylose (unbranched)
Figure 2.20
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Polysaccharides (Carbohydrates)
Amylopectin (branched)
Glycogen
Figure 2.20
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Macromolcule Proteins

• Polymers made from 20 essential amino acids
• Amino acids are held together by peptide bonds
• The R side chain determines polarity of the
  protein

Monomer
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Monomer Amino Acids
Catagories of Amino Acids

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Monomer Amino Acids
Catagories of Amino Acids


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Formation of a Peptide Bond
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Protein Structure
- amino acid sequence
folding into specific, repeated structures
3-demensional shape formed by polypeptide
chain structure formed by
interactions of multiple chains
Figure 2.24
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Protein Structure
Figure 2.24
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Macromolecule Nucleic Acids
Monomers
33
DNA and RNA
34
Formation of Nucleotide Polymers
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Macromolecules
Figure 2.26
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Macromolecule Lipids

• Very heterogeneous group
• Found in all cellular membranes
• Fatty-acid types
• Nonfatty-acid types steroids

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Fats - triglycerides

no double bonds between carbons
double
bonds present between carbons
Figure 2.15
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Phospholipids

• fatty acid chain
• polar head group

Figure 2.16
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Phospholipids
Figure 2.16
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Steroids

• Common in plasma membrane of eukaryotic cells
• Examples include
• Cholesterol, cortisone, progesterone, testosterone

Figure 2.17
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Macromolecules of the Cell
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Characteristics of Chemical Bonds