Biomolecules:
Structure
Function
Most of the molecules in your body are one of
four things:
- carbohydrates a
d
- lipids
b
- proteins
- nucleic acids
c
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General formula is (CH2O)n
Classified as Simple or Complex
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Simple = one carbohydrate unit (glucose) =
monosaccharide
Complex = many carbohydrate units (starch) =
polysaccharide
Provide major source of easily
accessible energy
Water soluble
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Glucose is the monosaccharide most
readily used by cells, and the only source of
energy for the brain
Starch is a polysaccharide stored in roots
and seeds for future energy needs
Cellulose is indigestible in humans and is
used by plants to provide rigidity
Glycogen is how animals store
carbohydrates for future needs
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Cereal grains such as wheat and rice contain
many complex carbohydrates
Root crops such as potatoes and carrots contain
large quantities of carbohydrates
Fruits contain many sugars (monosaccharides
and disaccharides)
Candy, soda, and other sweets are very high in
monosaccharides
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A lipid is the technical name for a triglyceride (fat) or
steroid (cholesterol)
Triglycerides are a glycerol attached to 3 fatty acids
The fatty acids are non-polar, long hydrocarbon
chains
A chain with all single bonds is saturated
 A chain with one or more double bonds is unsaturated.
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Saturated fats have the maximum number
of hydrogen atoms on them
Saturated fats tend to be solids at room
temperature
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Unsaturated fats, with their double bonds, can
hold more hydrogen atoms
Unsaturated fats tend to be liquids at room
temperature
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Very large molecules
Fundamental to structure and function of all
organisms
Often consist of 2 or more subunits held in place
by covalent bonds
Each subunit is made of a very long chain of
amino acids which folds up on itself
Bond joining amino acids is called a peptide bond
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Basic structure of an amino acid:
O
H
HO
Acid group
NH2
R
Functional Group
Amine
Group
The amino acid
is determined
by the “R”
group, shown
here in blue.
Note that small
differences in
the “R”
structure result
in a totally
different amino
acid.
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The structure of a protein is determined by
the order of the amino acids and their
respective polarities
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Non-polar functional groups attract non-polar
functional groups
Polar functional groups attract polar functional
groups
The protein folds as the different functional
groups are attracted to each other and the
protein takes its shape in this manner
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Meats, eggs, seafood are all
excellent sources of protein but
contain significant amounts of
fat
Dairy products are also good
sources of protein but contain
sugar (lactose) and fat
Legumes, including beans and
lentils, are excellent sources of
protein
Soy products such as tofu are
excellent sources of protein
Egg whites are pure protein; all
the fat in an egg is in the yolk
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Proteins have many functions
Provide structure (hair, nails, muscle)
 Enzymes = catalyze chemical reactions
 Hormones = signaling between tissues
 Antibodies = recognizing pathogens (germs)
 Storage and Transport
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 Across cell membrane
 Hemoglobin
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With your seat partner:
1. Without looking at your notes, name 3
different foods that contain each of the 3
biomolecules we’ve discussed so far?
2. Why do you think it is important for our
bodies to get a balanced diet of all of these
foods?
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Nucleic acids are found in the nucleus
Contain information that is passed from
generation to generation – genetic material
Two forms
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Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
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DNA stays in nucleus
Double helix
EXTREMELY large
Nitrogenous bases
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Adenine
Guanine
Cytosine
Thymine
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RNA leaves nucleus
Single strand
Large, but not very
Nitrogenous bases:
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Adenine
Guanine
Cytosine
Uracil
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1. What are the 4 macromolecules most common in living
organisms?
2. Which macromolecule includes starches and sugars?
3. What is the difference between saturated and
unsaturated fats?
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4. What are the building blocks of proteins called?
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5. What are 3 things our body uses proteins for?
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6. Which type of nucleic acid uses deoxyribose sugar?