Chapter 2
Biomolecules
Macromolecules
• Biological macromolecules are
defined as large molecules made up
of smaller molecules.
• There are 4 classes of
macromolecules:
–
–
–
–
Carbohydrates
Lipids
Proteins
Nucleic acids
Macromolecules
• Each macromolecule is made up of
smaller organic molecules.
• These smaller molecules are called
monomers.
• Monomers that are bonded
together are called polymers.
Carbohydrates
•Made of carbon (C),
hydrogen (H), and
oxygen (O) atoms,
always in a ratio of 1:2:1
•The key source of
energy used by living
things.
•Carbohydrates are
sugar molecules.
•The simplest
carbohydrate is a
monosaccharide (a
simple sugar).
–An example of a
monosaccharide is
glucose.
Carbohydrates
•Monomers of
monosaccharides
bond together to
form more complex
sugars.
–Disaccharides
–Polysaccharides
Polysaccharides
• Starch
– A storage polysaccharide found in
plants
– Found in potatoes, pasta & bread
(wheat)
• Cellulose
– A major component of a plant cell wall.
– Found in raw plants/vegetables (it’s
what gives the crispness).
– Used to make paper.
• Glycogen
– Long term storage of energy for
animals.
– Broken into glucose monomers for
energy source.
Carbohydrate Test - Glucose
•To test for the
presence of glucose we
will use the Benedict’s
Test.
•A positive reaction in a
Benedict’s Test is the
change of the clear light
blue solution to an
opaque orange-brown
solution in a boiling
water bath.
•This color change
indicates the presence
of Glucose in a given
solution.
Carbohydrate Test - Starch
•To test for the
presence of starch, the
Lugol’s Iodine Test is
used.
•This is a simple test in
which iodine is added
to a given solution.
•If iodine added to a
solution turns blackblue then starch is
present. If the solution
remains the color of
iodine, reddishorange, there is no
starch present, a
negative test.
Lipids
• The base elements of these
molecules are C, H and O.
• The body stores lipids as reserve
energy.
• Lipids function to:
– Insulate our bodies
– Protect our bodies
– Give us long term energy storage
• Lipids are commonly known as fats,
oils and waxes.
Lipids
• Lipids are made of one monomer of
glycerol and 2 or 3 fatty acids.
Lipid Test
• The best way to test for the
presence of lipids is the Brown
Paper Test.
• A substance is placed on a piece of
brown paper.
• A positive test for lipid will leave an
“oily” spot on the brown paper.
Proteins
• Proteins are the most complex and
functionally diverse molecules of living
organisms.
• Proteins compose enzymes, blood cells,
antibodies and muscle tissue just to
name a few and are therefore associated
with meat products.
• The base elements of proteins are C, H, O
and N.
• The monomers of proteins are 20
different amino acids.
• The main function of proteins is for
growth and repair of tissues in the body.
Protein
Monomer
Polymer
Protein Test
• We test for the presence of protein
using the Biuret Test.
• A violet color is a positive reaction
for protein in a Biuret Test.
Nucleic Acids
• There are two kinds of nucleic acids
– DNA and RNA.
• DNA carries genetic information
and is responsible for heredity.
• Both are involved in the creation of
proteins.
Nucleic Acids
• Nucleic acids are made of
monomers called nucleotides.
• Nucleotides have 3 parts:
– Sugar
– Phosphate
– Nitrogen Base
Biomolecules Table
Carbohydrates
Elements
Function
(What is it used for?)
Building Blocks
(What pieces is it
made of?)
Examples
How do we test for it?
Lipids
Nucleic Acids
Proteins
Enzymes
Enzymes
• Many slow reactions are essential for an
organism to survive but, are not quick
enough to sustain life.
• Biological catalysts are chemical agents
that influence the rate of a reaction
without changing or affecting the
reaction.
• An enzyme is a biological catalyst that
allows reactions to occur at much higher
rates.
• With the help of enzymes, those slow
reactions can occur quickly enough to
sustain life.
How do enzymes work?
• The amount of energy needed to begin
a reaction is known as the activation
energy.
• Enzymes speed up reactions by lowering
this activation energy.
• This allows reactions to proceed much
faster than they would have with a
higher energy barrier.
How do enzymes work?
Enzyme Structure
• Enzymes are substrate-specific.
• This means they are very “picky” and only
react with specific substrates to form
products.
• In a normal enzymatic reaction the enzyme
and substrate collide randomly in a solution
and join at the enzyme’s active site.
• This collision works much like a lock and key
effect.
• The active site has a specific shape that only a
particular substrate fits into.
• When the two are joined they react and the
substrate is converted into a product.
• Once the reaction is complete the enzyme and
newly formed product separate with the
enzyme left unchanged.
Enzyme Structure
Enzyme Action
• Enzymes can be “turned off” or
made inactive by:
–
–
–
–
Change in temperature
Change in pH
Removal of substrate
Addition of inhibitors
• This is called denaturation because
it changes the shape of the
enzyme.