MICROBIOLOGY (BIOL& 260)
CHAPTER 2
BASIC PRINCIPLES OF CHEMISTRY
ATOM COMPONENTS
Electrons--negatively charged and found in energy levels (orbitals) around the nucleus
Protons--large, positively-charged particles found in the nucleus
Neutrons--large, neutral particles found in the nucleus which separate protons (with
wrong ratio of p/n--->radioisotope)
ATOMIC WEIGHT AND ATOMIC NUMBER
Atomic number
1. smaller of the two numbers on periodic table
2. indicates number of protons (also electrons)
Atomic weight
1. mass of the atom
2. equals number of neutrons plus number of protons
CHEMICAL BONDING
Ionic bonds--attraction of cations (+) and anions (-); loss or gain of electrons created
cations and anions
Covalent bonds--sharing of electrons; shared electrons spend time around both elements
sometimes unequally (polar covalent bond--example: water)
Hydrogen bonding--hydrogen atom of one molecule is attracted to the oxygen or
nitrogen of a second; weaker than ionic and covalent bonds
TYPES OF CHEMICAL REACTIONS
Endergonic reactions--absorbs energy
Exergonic reactions--releases energy
Synthesis reactions--form chemical bonds; require energy
Decomposition reactions--break chemical bonds; release energy
Exchange reactions--change chemical “partners”
WATER’S UNIQUE CHARACTERISTICS
1. Strong attraction between water molecules
2. High boiling point
3. Ice is less dense the liquid water
4. Excellent solvent
5. Excellent temperature buffer
ACIDS AND BASES
Acids release hydrogen ions or are proton donors
Bases release hydroxide ions or are proton acceptors
pH is the measure of the hydrogen ions in a substance or liquid; <7=acidic; >7=basic
Buffers resist changes in pH
ORGANIC CHEMISTRY: THE CHEMISTRY OF LIFE
CARBOHYDRATES
1. Sugars (C, H, O)
2. provides energy
3. component of DNA and RNA
4. component of cell walls
5. Monosaccharide (glucose)
6. Disaccharide (sucrose)
7. Polysaccharides (starch, cellulose)
LIPIDS
1. Nonpolar (insoluble in water)
2. fats (triglycerides)--composed of three fatty acids and glycerol
a. saturated fat-- maximum number of hydrogen atoms; single bonds between carbons
b. unsaturated fats--less than maximum hydrogen atoms; double bonds between
carbons
3. phospholipids--a phosphate group is present instead of one fatty acid; phosphate
portion is polar--fatty acid portion is nonpolar; soaps and detergents are examples of
phospholipids
4. steroids--composed of a four ring structure; component part of cell membranes in
eucaryotes
PROTEINS
1. Functions
a. enzymes
b. carrier proteins
c. bacteriocins
d. allow for movement
e. involved in defense (antibodies)
2. Composed of amino acids (20 different)
3. Protein structure levels
a. primary
b. secondary
c. tertiary
d. quarternary
NUCLEIC ACIDS
A. DNA (deoxyribonucleic acid)
1. double-stranded (double-helix)
2. deoxyribose
3. A,T,C,G
B. RNA (ribonucleic acid)
1. single-stranded
2. ribose
3. A,U,C,G
C. ADENOSINE TRIPHOSPHATE
1. Principle energy molecule of the cell
2. ATP breaks up to produce ADP plus phosphate; a high energy bond is broken
releasing energy
LEARNING OBJECTIVES FOR CHAPTER 2
Following successful study of this chapter students should be able to:
1. Define or describe each of the following terms: electrons, protons, neutrons, nucleus,
chemical element, isotopes, electron shells, valence, compound, chemical bonds, ions,
cations, anions, atomic number, atomic weight, endergonic reactions, exergonic
reactions, synthesis reactions, anabolism, decomposition reactions, catabolism, exchange
reactions, collision theory, activation energy, reaction rate, catalysts, enzymes, substrate,
enzyme-substrate complex, inorganic compounds, organic compounds, polar molecules,
solvent, solute, acid, base, salt, pH, buffers, dehydration synthesis, monosaccharides,
disaccharides, polysaccharides, hydrolysis, steroids, amino acids, peptide bond,
denaturation, DNA(deoxyribonucleic acid), RNA(ribonucleic acid), nucleotide, double
helix, adenosine triphosphate
2. List and describe the various types of chemical bonds (ionic, covalent, hydrogen)
3. Describe the characteristics of each of the following organic compounds:
carbohydrates, lipids, proteins, nucleic acids
4. List and describe the unique characteristics of water