Study Guides
Big Picture
Biochemistry is the study of the structure and properties of molecules in living organisms. Our body is made out of four
basic classes of biomolecules: carbohydrates, lipids, proteins, and nucleic acids. Each class performs a unique role and
is vital for the function of life.
Key Terms
Biomolecule: A molecule created within an organism.
Carbohydrate: A biomolecule containing carbon, hydrogen, and oxygen that supply the energy living systems need
Chemistry
Biochemistry
to survive.
Lipid: A biomolecule produced for storing energy.
Protein: A biomolecule making up muscles, enzymes, and other organs in the body.
Nucleic Acid: A biomolecule used to store genetic information.
Monomer: One basic building block of a biomolecule.
Polymer: A long chain of monomers.
Fatty Acid: A long hydrocarbon chain ending in a carboxylic acid group (-COOH).
Amino Acid: This is the monomer of a protein, which consists of an amine group (NH2-), a carboxylic acid group
(-COOH), and a carbon side-chain.
Four Main Types of Biomolecules
There are 4 main types of biomolecules responsible for
cellular functions within cells. These are carbohydrates,
lipids, proteins, and nucleic acids.
• Each biomolecule is made up of monomers.
• Monomers lose a water molecule when they
A table of the monomers and polymers of
biomolecules
Biomolecule
combine
into polymers in dehydration synthesis.
• The
breakdown of polymers into monomers for
digestion in the body occurs in hydrolysis, where
water is added to the polymer.
Monomer
Polymer
carbohydrate monosaccharide
polysaccharide
lipid
fatty acid
triglyceride
protein
amino acid
polypeptide
(protein)
nucleic acid
nucleotide
nucleic acid
(DNA and RNA)
This is why you need to drink water when you eat!
Carbohydrates
Carbohydrates are sugars used to provide energy to your body. They perform specific functions depending on their
structure. The basic formula for carbohydrates is (CH2O)n, where n can be any number of repeating monosaccharides.
• Monosaccharide:
The monomer of a carbohydrate.
Examples are glucose, fructose, and galactose.
• Polysaccharide:
A polymer chain of monosaccharides
connected with glycosidic linkages (bonded through an
oxygen). Examples are sucrose (table sugar) which is
glucose and fructose, and lactose, which is glucose and
galactose. Longer chains also exist, such as starch,
which is a chain of glucose, and is broken down and
digested by the body for energy.
Figure: Starch polymer showing individual glucose monomers
connected by glycosidic linkages.
Lipids
• Monounsaturated
fatty acid: A fatty acid with one
double bond.
• Polyunsaturated fatty acid: A fatty acid with more than
one double bond.
Image Credit: Wolfgang Schaefer, Public Domain
Figure: The general formula of a fat triglyceride molecule. On
the left is the glycerol molecule (the 3-carbon chain and the
three oxygens it is attached to), and three different fatty acids
attached to the molecule.
This guide was created by Steven Lai, Rory Runser, and Jin Yu. To learn more
about the student authors, visit http://www.ck12.org/about/about-us/team/
interns.
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v1.11.4.2011
Disclaimer: this study guide was not created to replace
your textbook and is for classroom or individual use only.
Lipids are fats. A triglyceride is the most common type of
lipid and consists of three fatty acids attached to a glycerol
molecule. They are used to store energy in our body. Lipids
also include phospholipids, which have a phosphate group
attached to a fatty acid and make up cell linings, and
steroids, which have four carbon rings bounded together
with branches and functional groups.
• Saturated fatty acid: A fatty acid with no double bonds.
Every carbon is saturated with hydrogens.
Chemistry
Biochemistry
cont .
Four Main Types of Biomolecules (cont.)
Proteins
Proteins, also called polypeptides, are
made out of amino acids and are
connected with peptide bonds.
• There are 20 amino acids, which, like
the alphabet, can be arranged in any
order and number to form a nearinfinite number of polypeptides.
Structure of a Protein
• The
shape of a protein is important
for function. There are four different
structures that proteins can form
in the body. Large enough proteins
fold, twist, and bend in certain ways
to give them the right shape and
structure.
Nucleic Acids
Figure: This shows the four steps that a polypeptide chain undergoes to become a
fully-functioning protein.
Nucleic acids include DNA, which is double-stranded,
and RNA, which is single-stranded. Nucleic acids are
made up of nucleotides joined with phosphodiester
bonds. There are five different types of nucleotides,
which are split into the pyrimidines and the purines.
The pyrimidines are cytosine (C) and thymine (T). In
RNA, thymine is replaced with uracil (U). The purines
are adenine (A) and guanine (G). Adenine bonds only
with thymine (uracil in RNA), and cytosine only with
guanine.
A clever way to remember that A goes with T
and C goes with G is the phrase Chicken Gravy,
Apple Tart. Another way to remember this is
the phrase All Tigres Can Growl.
• DNA:
A double-stranded chain of deoxyribonucleic
acids that forms a double-helix through hydrogen
bonding. It holds the genetic information of most
complex cells.
• RNA:
A single-stranded chain of ribonucleic acids.
It holds the genetic information of some less complex organisms and is involved with protein synthesis in complex cells.
Figure: This picture shows the differences between DNA and
RNA, and the constituent nucleic acids associated with each
one.
Image Credit: Sponk, CC-BY-SA 3.0
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Image credit