CHEMISTRY OF LIFE
A. Inorganic compounds—without carbon
1. Water (H2O)—most important inorganic compound
a.
excellent solvent (universal)—because it is polar
covalent
b.
high heat capacity
2. Acids and bases—measured on pH scale. Fluctuations in
pH can change the rate and nature of internal chemical
reactions.
a.
Acid—strong acids, pH near 0. Characterized by
an abundance of H30+ (hydronium) ions.
b.
Base—strong bases pH near 14. Characterized by
an abundance of OH- (hydroxide) ions.
B. Organic compounds—compounds containing carbon. Most
composed of basic units that repeat. These units are called
monomers. Polymers are formed from the condensation of
many monomers and are called macromolecules.
1. Carbohydrates—contain carbon, hydrogen, and oxygen
(have ratio of 2 hydrogen atoms and 1 oxygen atom per
carbon atom). The body’s main source of energy and used
as structural compounds.
a.
Monosaccharides—simple sugars; monomers of
carbohydrates. Common monosaccharides include
glucose, fructose, and galactose. All have the simple
formula of C6H12O6.
b.
Disaccharides—double sugars. Formed from the
condensation of two monosaccharides. Examples
include:
(1)
(2)
(3)
c.
Maltose (malt sugar)—glucose + glucose
Lactose (milk sugar)—glucose + galactose
Sucrose (table sugar)—glucose + fructose
Polysaccharides—complex sugars. Composed
of long chains of monosaccharides.
(1)
Starch—plant energy storage, polymer of
glucose. Forms single line chains of
molecules.
(2) Glycogen—animal energy storage, polymer
of glucose. Forms branching chains of
molecules.
(3) Cellulose—indigestible, dietary fiber for
animals. Forms the cell wall of many plant
cells.
(4) Chitin—makes up the exoskeleton of
arthropods and cell walls of fungi.
2. Lipids—also contain carbon, hydrogen, and oxygen,
but in a different ratio than carbohydrates. Include fats,
oils, waxes, and steroids (fat based hormones).
More complex than carbohydrates. Triglycerides
(found in fats and oils) are made of glycerol + three
fatty acids. More energy per gram than carbohydrates.
Used for energy storage, cell membranes, and in the
nervous system.
3. Proteins—basic building blocks of tissues; monomers of
proteins. Contain carbon, hydrogen, and oxygen as well as
nitrogen and sulfur. Made of monomers called amino
acids. Used structurally and as biological catalysts
called enzymes.
a. Amino acids—monomers of proteins; made of an
organic acid or carboxyl group (COOH), amino
group (NH2), single carbon atom attached to
hydrogen, and an R-group. Each of the twenty
(20) different amino acid differs in the R-group.
b. Dipeptides—two amino acids joined by peptide
bonds.
c. Polypeptides—three or more amino acids joined
by peptide bonds. All proteins consist of these.
The sequence of amino acids determines the type
of protein. Shapes of protein molecules vary with
the sequence of the amino acids and determine
their properties.
Enzymes—proteins that act as biological catalysts.
a.
Names of many enzymes end in “ase”.
Examples include sucrase (works on
sucrose) and maltase (works on maltose).
b.
Each enzyme works on a specific substrate.
c.
They lower the amount of activation energy
needed to start reaction.
d.
Vitamins may act as co-enzymes.
5. Nucleic acids—carry instructions for cellular activity.
a.
DNA (deoxyribonucleic acid)—records
instructions and transmits them from generation to
generation. Found primarily in the nucleus of the
cell.
b.
RNA (ribonucleic acid)—reads and carries out
instructions. Found in nucleus and cytoplasm of
the cell.
Both are made of complex monomers called nucleotides.