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Macromolecules and Enzymes Study Guide (Sections 2-3 and 2-4)
I. pH Scale
A. General Characteristics
•
Indicates the concentration of H+ ions
•
Ranges from 0 – 14
•
pH of 7 is neutral (equal amounts H+ and OH-)
•
pH 0 up to 7 is acid … H+
•
pH above 7 – 14 is basic… OH•
Each pH unit represents a factor of 10X change in concentration
• Why Care About pH?
•
The H+ ions formed in acids (and the OH- ions formed by bases) can
cause certain chemical reactions that may interfere with a cell’s normal
functioning (can lead to cell death)
B. Buffers
• Weak acids or bases that react with strong acids or bases to prevent sharp, sudden
changes in pH
• Produced naturally by the body to maintain homeostasis
II. Carbon Compounds (Section 2-3 Pages 44-48)
A. General Carbon Characteristics
 Carbon is 6th element on the Periodic table
 Carbon can form covalent bonds to 4 other atoms (simultaneously)
 Carbon can also form bonds to other carbons
 Any molecule that contains carbon is called an “organic molecule”
o All organic molecules are combinations of: carbon, oxygen, hydrogen,
phosphorus, and nitrogen
B. Macromolecule- large molecules found in cells that are made up of hundreds of
thousands of other smaller molecules
 Biological macromolecules are usually also organic molecules
1. Macromolecules are polymers made from combinations of polymers
2. The four types of macromolecules we studied are: carbohydrates, lipids,
nucleic acids, proteins
1. Proteins/ Enzymes
A. General Protein Characteristics
1. Made of monomers called amino acids
a. amino acids consist of an amino
group, carboxyl group, and an R-group
b. R-groups are different between amino
acids
c. Proteins are used in cells to form
structures, fight disease, and to catalyze chemical
reactions
B. Enzymes- proteins that catalyze chemical reactions
1. Chemical Reaction- A process that changes one set of chemicals (reactants)
into another (products)
Chemical reactions involve changes in the chemical bonds that join atoms in
compounds
2. Enzyme Characteristics:
a. Bring 2 molecules close together in proper orientation
b. Lower the activation energy needed for reaction



Substrate- reactants of an enzyme-catalyzed reaction
Active site- region of enzyme that contacts substrate
Products- transformed substrate molecules (enzyme does not change)
3. Naming of Enzymes – most are named by adding “ase” to the substrate
4. Sometimes an enzyme needs help
 Helper molecules are called cofactors (or coenzymes)
5. Factors Influencing Enzyme Activity
a. Anything that affects the shape of the enzyme (protein)
1. pH, Temperature, Substrate concentration
b. Inhibitory Molecules
1. Competitive inhibitors
 Fit in active site but are not changed; prevent normal
substrate from binding, prevent reaction.
2. Non-competitive inhibitors (allosteric inhibitor)
 Bind permanently to other site which changes
molecular shape; prevents reaction.
2. Nucleic Acids
a. Made of monomers called nucleotide
b. Store information in the cell
c. Examples are RNA and DNA
d. When amino acids combine to form nucleic acids
the reaction is termed a “dehydration synthesis” and peptide
bond is formed. (see picture to the right).
3. Lipids
a. composed of glycerol combined
with fatty acid chains
b. store energy, create waterproof
coverings, and are used as hormones
c. fats, oils, and waxes are
examples
d. When glycerol combines with
fatty acid chains, the reaction is termed a “dehydration synthesis” and an ester bond is
formed. (see below picture).
4. Carbohydrates
a. composed of monomers called
monosaccharides
b. function to release energy as well as
structural purposes
c. composed of carbon, hydrogen, and
oxygen in a 1:2:1 ratio
d. names of carbohydrates typically end in
the suffix “-ose”
e. When monosaccharides combine to form
polysaccharides, the reaction is termed a
“dehydration synthesis” (see picture below) and a
glycosidic bond is formed.