Chapter 5 Study Guide
Vocabulary:
Word Roots:
con- = together
di-= two
glycol-= sweet
hydro-= water
-lyse = break
macro-= large
mono-= single
-sacchar = sugar
poly-= many
tri-= three
Key Terms:
alpha helix: A spiral shape constituting one form of the secondary structure of
proteins, arising from a specific hydrogen-bonding structure.
amino acid: An organic molecule possessing both carboxyl and amino groups.
Amino acids serve as the monomers of proteins.
beta pleated sheet: One form of the secondary structure of proteins in which the
polypeptide chain folds back and forth. Two regions of the chain lie parallel to each
other and are held together by hydrogen bonds.
carbohydrate: A sugar (monosaccharide) or one of its dimers (disaccharides) or
polymers (polysaccharides).
cellulose: A structural polysaccharide of cell walls, consisting of glucose monomers
joined by glycosidic linkages.
cholesterol: A steroid that forms an essential component of animal cell membranes
and acts as a precursor molecule for the synthesis of other biologically important
steroids.
condensation reaction: A reaction in which two molecules become covalently
bonded to each other through the loss of a small molecule, usually water; also called
a dehydration reaction.
dehydration reaction: A chemical reaction in which two molecules covalently bond
to each other with the removal of a water molecule.
denaturation: In proteins, a process in which a protein unravels and loses its native
conformation, there by becoming biologically inactive. Denaturation occurs under
extreme conditions of pH, salt concentration, and temperature.
deoxyribonucleic acid (DNA): A double-stranded, helical nucleic acid molecule
capable of replicating and determining the inherited structure of a cell’s proteins.
deoxyribose: The pentose sugar component of DNA, having one less hydroxyl group
than ribose, the sugar component of RNA.
disaccharide: A double sugar, consisting of two monosaccharides joined by
dehydration synthesis.
disulfide bridge: A strong covalent bond formed when the sulfur of one cysteine
monomer bonds to the sulfur of another cysteine monomer.
double helix: The form of native DNA, referring to its two adjacent polynucleotide
strands wound into a spiral shape.
fat: A biological compound consisting of three fatty acids linked to one glycerol
molecule.
fatty acid: A long hydrocarbon chain carboxylic acid. Fatty acids vary in length and
in the number and location of double bonds; three fatty acids linked to a glycerol
molecule form fat.
glycogen: An extensively branched glucose storage polysaccharide found in the
liver and muscle of animals; the animal equivalent of starch.
glycosidic linkage: A covalent bond formed between two monosaccharides by a
dehydration reaction.
hydrolysis: A chemical process that lyses, or splits, molecules by the addition of
water.
lipid: One of a family of compounds, including fats, phospholipids, and steroids, that
are insoluble in water.
macromolecule: A giant molecule formed by the joining of smaller molecules,
usually by a condensation reaction. Polysaccharides, proteins, lipids and nucleic
acids are macromolecules.
monomer: The subunit that serves as the building block of a polymer.
monosaccharide: The simplest carbohydrate, active alone or serving as a monomer
for disaccharides and polysaccharides. Also known as simple sugars, the molecular
formulas of monosaccharides are generally some multiple of CH2O.
nucleic acid: A polymer (polynucleotide) consisting of many nucleotide monomers;
serves as a blueprint for proteins and, through the actions of proteins, for all cellular
activities. The two types are DNA and RNA.
nucleotide: The monomer of a nucleic acid, consisting of a five-carbon sugar
covalently bonded to a nitrogenous base and a phosphate group.
peptide bond: The covalent bond between two amino acid units, formed by a
dehydration reaction.
phospholipid: A lipid molecule that is a constituent of the inner bilayer of biological
membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.
polymer: A long molecule consisting of many similar or identical monomers linked
together.
polynucleotide: A polymer consisting of many nucleotide monomers; serves as a
blueprint for proteins and, through the actions of proteins, for all cellular activities.
The two types are DNA and RNA.
polypeptide: A polymer (chain) of many amino acids linked together by peptide
bonds.
polysaccharide: A polymer of up to over a thousand monosaccharides, formed by
dehydration reactions.
primary structure: The level of protein structure referring to the specific sequence
of amino acids.
protein: A three-dimensional biological polymer constructed from a set of 20
different monomers called amino acids.
purine: One of two types of nitrogenous bases found in nucleotides. Adenine (A)
and guanine (G) are purines.
pyrimidine: One of two types of nitrogenous bases found in nucleotides. Cytosine
(C), thymine (T), and uracil (U) are pyrimidines.
quaternary structure: The particular shape of a complex, aggregate protein, defined
by the characteristic three-dimensional arrangement of its constituent subunits,
each a polypeptide.
ribonucleic acid (RNA): A type of nucleic acid consisting of nucleotide monomers
with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G),
and uracil (U); usually single-stranded; functions in protein synthesis and as the
genome of some viruses.
ribose: The pentose sugar component of RNA.
saturated fatty acid: A fatty acid in which all carbons in the hydrocarbon tail are
connected by single bonds, thus maximizing the number of hydrogen atoms that can
attach to the carbon skeleton.
secondary structure: The localized, repetitive coiling or folding of the polypeptide
backbone of a protein due to hydrogen bond formation between the polypeptide
backbone region.
starch: A storage polysaccharide in plants consisting entirely of glucose.
tertiary structure: Irregular contortions of a protein molecule due to interactions of
side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and
disulfide bridges.
unsaturated fatty acid: A fatty acid possessing one or more double bonds between
the carbons in the hydrocarbon tail. Such bonding reduces the number of hydrogen
atoms attached to the carbon skeleton.
Chapter 5 Important Points:
Formation of macromolecules (large molecules):
 Example of emergent properties in that particular grouping of atoms of
certain elements produce characteristics that assign those molecules to
recognizable categories of structure and function.
 General polymer structure of repeating monomers (except for lipids)
o New bonds joining free monomers to polymer chains are created
by dehydration synthesis; water molecule produced
o Existing bonds broken when monomers released by hydrolysis;
water molecule used
4 classes of macromolecules:
1. Carbohydrates (sugars)
a. Monomer: monosaccharide
b. Bond: glycosidic linkage
c. Di-saccharide: Joining of 2 monosaccharides
d. Polysaccharides: long chain of many monosaccharides
e. Function:
i. Structural in plant: cellulose in plant cell wall
ii. Storage of chemical energy in plants: starch
iii. Storage in animals: glycogen
2. Lipids
a. Monomer: None
b. Bond: ester linkage joining fatty acids to glycerol in phospholipids
and fats
c. Some portion hydrophobic due to non-polar covalent bonds
between carbon and hydrogen atoms
d. 3 classes
i. Phospholipids
1. 2 fatty acids (hydrophobic) + glycerol + phosphate
group (hydrophilic)
2. Main component of membranes
3. Exists as bilayer in aqueous environments
ii. Steroids
1. 4 fused carbon rings
2. Ex. Cholesterol, sex hormones
iii. Fats
1. 3 fatty acids + glycerol
2. Entirely hydrophobic
3. Unsaturated (heart healthy fats)
a. One or more double bond in fatty acid tails
b. Liquid at room temperature
4. Saturated (heart unhealthy fats)
a. No double bonds in fatty acid tails
b. Solid at room temperature
3. Proteins: Very diverse class of many cellular and bodily functions
a. Monomer: amino acids
i. 20 amino acids
1. All contain carboxyl and amino group
2. R or side chain unique for each of the 20
a. Some R groups non-polar, polar or ionic
b. Bond: Peptide bond
c. Conformation (3D structure necessary for proper protein
function) created by:
i. Primary structure:
1. Unique sequence of amino acids for each protein
ii. Secondary structure:
1. Hydrogen bonds form between areas of protein
backbone
a. Alpha helix
b. Beta pleated sheet
iii. Tertiary structure:
1. Bonds between R groups of different amino acids
iv. Quaternary structure:
1. Some proteins (but not all) require grouping of 2 or
more polypeptide chains for function
d. Denaturation
i. Lose of conformation and function of protein
ii. Environmental conditions such as temperature and pH can
disrupt conformation
4. Nucleic Acids: Contains the genetic information passed between
generations; instructions for making proteins
a. Two types:
i. Deoxyribose nucleic acid (DNA)
ii. Ribonucleic acid (RNA)
b. Monomer: Nucleotide
i. Phosphate group
ii. 5 carbon (pentose) sugar
1. Deoxyribose (DNA)
2. Ribose (RNA)
iii. Nitrogenous base
1. Purines: 2 rings of nitrogen
a. Adenine (A) and Guanine (G)—both RNA and
DNA
2. Pyrimidines: 1 ring of nitrogen
a. Cytosine (C)—both RNA and DNA; Thymine
(T)—DNA only; Uracil (U)—RNA only
c. Bonds:
i. Complementary nitrogenous base pairs in double helix of
DNA held together by hydrogen bonds
1. A-T
2. G-C
ii. Sugar phosphate backbones held by phosphodiester bonds