Biological Molecules
The Building Blocks of Life
• Before we begin, get out a piece of paper,
put your name on it, and do the following:
• As review, sketch a diagram of an atom
and label the particles.
• Sketch a water molecule, and state what
kind of bonds form between the oxygen
and hydrogen atoms in water.
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Which four elements make up about 96%
of living matter?
1. carbon, hydrogen,
nitrogen, oxygen
2. carbon, sulfur,
phosphorous,
hydrogen
3. carbon, oxygen,
sulfur, calcium
4. oxygen, hydrogen,
calcium, sodium
81%
13%
4%
1
2
2%
3
4
An atom of nitrogen attracts electrons more
strongly than an atom of hydrogen. Which of the
following best describes ammonia (NH3)?
25%
25%
25%
2
3
25%
1. The nitrogen is
slightly negative.
2. The nitrogen is
strongly positive.
3. The hydrogens are
slightly negative.
4. The hydrogens are
strongly positive.
1
4
Carbon is the backbone of organic molecules.
With an atomic number of 6, carbon can form up
to ___ different ___ bonds.
25%
1.
2.
3.
4.
25%
25%
2
3
25%
6; ionic
6; covalent
4; ionic
4; covalent
1
4
Atoms to Molecules
In our model of scale, remember that the marble
represented a small monomer, such as glucose.
Functional Groups
Functional groups
determine how a
molecule will
interact with other
molecules.
Why does sugar dissolve in water?
The methyl group, consisting of carbon bonded
to hydrogen, is an area of ___ in an organic
molecule.
50%
50%
1. Polarity
2. Non-polarity
1
2
If you see oxygen or nitrogen in the structure of
an organic molecule, expect that area to be:
50%
50%
1. Polar
2. Non-polar
1
2
One glucose molecule alone
is a monomer.
Two or more
glucose
molecules linked
together can
make a polymer.
Dehydration Synthesis
Two glucose
molecules
(monomers)...
...can bond together
to make maltose
(dimer).
Hydrolysis
A dimer such as
maltose, or any
other polymer...
...can be broken
apart into its
constituent
monomers.
Making/Breaking Molecules
Monomers or
Polymers?
The process
occurring between
C and A is:
The process
occurring between
A and C is:
Hydrolysis
Dehydration
Synthesis
What is given
off here?
H2O
What is taken
up here?
H2O
Monomer or
Polymer?
In our model of scale, large chain molecules
(polymers) are represented by the cat.
Carbohydrates
Monomers
Simple sugars, such as
glucose, are the
monomers of complex
carbohydrates.
Label a hydrogen group
and hydroxyl group on
the glucose diagram.
What are some
properties of these
groups?
What is similar about
these four simple
sugars?
What is different?
glucose
fructose
sucrose
What process do you see happening here to create this
glycosidic linkage between the two sugars?
What is the scientific term for a pair of monomers linked
together?
Glycosidic linkages between many
sugar molecules create complex
carbohydrates, such as starch.
What is the scientific
term for many
monomers linked
together?
Cellulose
Cotton
Hemp
Rayon
Linen
Dietary
“fiber”
What do you see in the structure of cellulose that tells
you that it is a carbohydrate?
How is cellulose similar to starch?
Cellulose vs. Starch
We can digest starch (amylose) but not cellulose.
What difference do you see that might be the reason
behind this?
Chitin
Pectin
In general, how
can we describe
complex
carbohydrates?
White death?
Some people claim that sugar is harmful, toxic,
or addictive. Is it?
http://ed.ted.com/lessons/how-sugar-affects-the-brain-nicole-avena
Fake sugar?
Complex carbohydrates are:
1. Polymers of simple
sugars.
2. Monomers of
simple sugars.
50%
1
50%
2
True or false: Sugars and starch have a lot
of fat in them.
1. True
2. False
50%
1
50%
2
• Look around you. What are some
specific examples of carbohydrates that
are in this room right now?
• List some specific carbohydrates that
you ate for breakfast. Not the foods that
they were in – name the carbohydrates
themselves.
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Lipids
Label a methyl group and a hydroxyl group on one
of the fatty acids. What are some properties of
these groups?
What process
do you see
happening here
to create these
ester bonds
between the
fatty acid chains
and the glycerol
in this
triglyceride?
Lipids that are solid
at room temperature
are composed mostly
of saturated fatty
acids.
Stearic acid (found in wax
and lard) and butyric acid
(found in butter) are
examples of saturated fatty
acids.
Lipids that are liquid at
room temperature are
composed mostly of
unsaturated fatty acids.
Oleic acid and linoleic acid
are unsaturated fatty acids
that are common in
vegetable oils.
Saturated vs. Unsaturated
A puzzle:
Shortening and margarine
labels often brag that their
products are made with healthy,
unsaturated vegetable oils.
Vegetable oils are liquid at room
temperature. So why are
shortening and margarine solid
at room temperature?
Trans fats?
Unsaturated fats bend
because of the cis
configuration
Trans configuration results in
an unsaturated fatty acid that
is a straight chain like a
saturated fatty acid
Trans fats are rare in nature. Hydrogenation can create both
saturated and trans fatty acids.
Phospholipids
Saturated or
unsaturated?
Label the phosphate group
on this phospholipid. What
are some properties of this
group?
Steroids
Fake fat?
What do you see in this molecular
structure that suggests why Olestra is
not digested? Why might it cause the
symptoms described on the label?
•
•
List some examples of lipids or fatty
acids – not the foods that contain them,
but specific lipids.
How are carbohydrates and lipids
different from one another?
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A fatty acid consists of:
1. A chain of carbon
and hydrogen
atoms.
2. A chain of sugar
molecules.
3. A chain of any
carbon-containing
monomers.
85%
7%
1
2
9%
3
Why can’t you mix oil and water?
1. Oil floats on water.
2. Oil is more dense
than water.
3. Oil is non-polar,
while water is
polar.
4. Oil is an organic
molecule, while
water is not.
93%
7%
0%
1
0%
2
3
4
Which of these is the largest
object?
1.
2.
3.
4.
A carbon atom.
A fatty acid.
A phospholipid.
A cell membrane.
25%
1
25%
25%
2
3
25%
4
Proteins
Monomers
Amino
group
Carboxylic acid
group
Amino acids are the monomers of proteins.
On your diagram, label the amino group and the
carboxylic acid group. What are some properties of
these groups?
R-groups
determine the
properties of
individual
amino acids.
What process do you see happening here to create this
peptide bond between the two amino acids?
What is the scientific term for many monomers linked
together?
Some proteins, like keratin, are structural proteins.
Actin and myosin fibers in muscle cells, spider webs, and
silk are also structural proteins.
Some proteins, such as insulin, are hormones.
Some proteins are enzymes that build or break down other
molecules in living cells.
Some proteins are structured to carry or move substances,
such as hemoglobin that carries oxygen, or cell membrane
proteins that move substances across the membrane.
Heat, acidity, or both can denature proteins. Denaturing
changes the shape of a protein, which changes its
appearance and functionality. Denaturing is what happens
when we fry an egg (egg whites contain albumin protein)
or use acids to turn milk into cheese (milk solids contain
casein proteins).
The shape of a protein determines its function.
The shape of an individual protein is determined by the
order of amino acids in the primary chain, which affects how
the amino acid chain twists and folds into the final shape of
the protein.
DNA contains the code that instructs the cell machinery to
put amino acids together in a particular order to make a
particular protein. As long as the DNA contains the correct
code, the protein will function. Mistakes in the code
(mutations) change the order of amino acids, which
changes the structure of the protein, which prevents the
protein from carrying out its function.
True or False: Meat is an example
of a protein.
1. True: Meat is an
important dietary
protein.
2. False: Meat is muscle
tissue that is made up
of many different
proteins, lipids, and
other molecules.
85%
15%
1
2
___ bonds are responsible for primary structure
of proteins, while ___ bonds contribute to the
secondary structure.
1.
2.
3.
4.
Ionic; covalent
Peptide; hydrogen
Peptide; covalent
Hydrogen; ionic
42%
26%
21%
12%
1
2
3
4
When we say “proteins are made of
amino acids,” it means that:
1. Proteins are larger
than amino acids.
2. Amino acids are
larger than
proteins.
3. Both amino acids
and proteins are
about the same
size.
33%
1
33%
2
33%
3
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List some examples of specific proteins
– again, not foods that contain proteins,
but specific proteins.
Why are there so many different kinds
of proteins?
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Nucleic Acids
Monomers
Label the parts
on this
nucleotide.
Is this a
nucleotide of
DNA or RNA?
How can you
tell?
Nucleotides link together to form nucleic acids. The
sugars bind to the phosphate groups to form the
backbone of the chain.
DNA is two strands of
nucleotides side-byside.
What is the type of
bond that forms the
cross-links holding the
two strands together?
ATP
Adenosine
triphosphate, the
universal energy
carrier, is a single
nucleotide (adenine)
with two extra
phosphate groups
attached.
DNA is found inside of the
nucleus of a:
1. Cell
2. Atom
3. Both
33%
1
33%
2
33%
3
Try to fill in this table from memory:
Monomers
Polymers
Examples
Simple sugars
Complex
Carbohydrates
Starch,
Cellulose, etc.
Proteins
Hemoglobin,
Keratin, etc.
Fatty acids &
glycerol
Lipids
Fats, waxes,
oils, steroids.
Nucleotide
Nucleic Acids
DNA, RNA
Amino acids
• Observe the structure of each of these
monomers and identify them.
1
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Amino Acid
Sugar
3
Fatty Acid
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• The circled objects in our scale model
represent...
Atom
Small
Molecule
Chain
Molecule
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Recap
• Atoms of carbon, hydrogen, oxygen, and a
few other elements bond together covalently
to make the biological molecules.
• Monomers (small molecules, such as
glucose) bond together to form polymers
(large chain molecules, such as complex
carbohydrates).
• The four classes of biological molecules are
carbohydrates, lipids, proteins, and nucleic
acids.