Organic Molecules and
Biomolecules
• Organic Chemistry is the chemistry of living organisms
• Inorganic Chemistry is the chemistry of nonliving things
• Organic molecules are defined as molecules containing
both carbon and hydrogen.
• Biomolecules are organic compounds found in living
things.
• There are only 4 categories of biomolecules- carbohydrates,
Carbon
• Carbon only has 4 electrons in its outer shell.
• To fill its outer shell to 8, carbon usually combines with
C, H, N, O. P, S which are the elements that make up
most of the weight of living things.
• Because carbon can combine with up to 4 other elements,
it makes it the perfect building block for biomolecules.
Hydrocarbons
• Long chains of C-C bonds with the only other element being hydrogen.
Octane
Hydrocarbons
• Carbon is also capable of forming double and triple bonds with itself. This
makes the molecule less flexible and influences the function of the molecule
Functional Groups
• Functional groups are specific combinations of bonded atoms that always
react in the same way, regardless of the carbon skeleton they are attached to.
• The functional group of a biomolecule is actually more important than the
carbon skeleton it is attached to.
Isomers
• Organic molecules that have the same molecular formula, but different
arrangement of elements.
• Ex: C3H6O3
Carbohydrates
• Carbohydrates are universally used as an immediate
energy source and they play structural roles for a variety
of organisms.
• Carbohydrates have a carbon to hydrogen to oxygen ratio
of 1:2:1
• Carbs include single sugar molecules and chains of
sugars.
Monosaccharides
• Monosaccharides are only a single sugar molecule
called a simple sugar.
• They can have a carbon backbone of 3 to 7
carbons
• Examples: Glucose and Ribose
Disaccharides
• Disaccarides contains 2 monsaccharides that have
joined during a dehydration reaction.
Polysaccharides
• Polymers of monosaccharides.
• When an organism needs energy, the polysaccharide is
broken down to release simple sugar molecules.
• The helical shape of the polysaccharides helps expose the
sugar linkages to enzymes when they break them down.
Polysaccharides
• Plants store glucose as starch. Potatoes store starch
during winter until energy is needed to grow in the
spring.
Polysaccharides branch at
the 6th carbon of the
monomer. (No main
carbon chain)
Polysaccharides
• Animals store glucose are glycogen. Our liver cells store
glycogen until energy is needed. The storage and release
of glycogen is controlled by hormones.
Polysaccharides
• Polysaccharides are used as storage molecules because
they are not soluble in water and are much larger than
simple sugars.
Polysaccharides
• Polysaccharides can be used as structural molecules
as well.
• Ex: Cellulose, Chitin, and peptidoglycan
Cellulose in plants.
Cellulose is the most
abundant carbohydrate
and organic molecule.
Animals cannot digest
the bonds between the
glucose monomers.
• Chitin in animals
and fungi. Found
in fungal cell walls
and exoskeletons
of crabs. Chitin
cannot be digested
by animals.
Lipids
• There are a variety of organic compounds classified as
lipids:
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Fats- butter, lard
Oils – cooking oils
Phospholipids- plasma membrane
Steroids- medicines
Waxes- candles, polishes
Triglycerides
• Fats and Oils contain 2 subunits: fatty acids and glycerol.
• Fatty acids contain an long hydrocarbon chain and a –
COOH (carboxyl functional group) Most contain 16 or18
carbons
• Fatty acids can be saturated, containing no double bonds
between carbons, or unsaturated, having double bonds
between carbons.
Triglycerides
• Glycerol is a 3-carbon compound with 3 –OH
(hydroxyl groups)
• -OH makes it polar, so therefore can mix with
water.
Triglycerides
• The –COOH of fatty acids and the –OH of
glycerol undergo a dehydration reaction and result
in a fat molecule and 3 molecules of water
Phopholipids
• Like triglycerides, but the third fatty acid contains a
phosphate group. This causes the fatty acid to
become polar and be the polar “head”
Steroids
• Steroids are different from fats and have skeletons of 4
fused carbon rings. Each type of steroids differ based
on the type of functional group attached to the
carbons.
• Cholesterol is a primary component to the cell
membrane and is a precursor of several other steroids.
Waxes
• In waxes, long chain fatty acids bone with long
chain alcohols.
Proteins
• Proteins are of primary importance to the structure and
function of cells.
• Some functions include:
• Metabolism, Support, transport, defense, regulation, and
motion.
Peptides