Topic 3.2: Carbohydrates, Lipids,
and Proteins
Assessment Statements
• 3.2.1: Distinguish between organic and inorganic
compounds
• 3.2.2: Identify amino acids, glucose, ribose and fatty acids
from diagrams showing their structure
• 3.2.3: List three examples each monosaccharides,
disaccharides, and polysaccharides
• 3.2.4: State one function of glucose, lactose, and glycogen
in animals, and of fructose, sucrose, and cellulose in plants
• 3.2.5: Outline the role of condensation and hydrolysis in
the relationships between monosaccharides, disaccharides
and polysaccharides; between fatty acids, glycerol and
triglycerides; and between amino acids and polypeptides
• 3.2.6: State three functions of lipids
• 3.2.7: Compare the use of carbohydrates and lipids in
energy storage
Introduction to carbohydrates, lipids,
proteins, and nucleic acids
Molecule
Subcomponents
Carbohydrates
Monosaccharides
Lipids
Glycerol and fatty acids
Protein (polypeptides)
Amino acids
Nucleic acids
Nucleotides
Common biochemical's and their
structure
• Molecules can be classified as being either
inorganic or organic
– All organic molecules contain the element carbon,
although not all carbon-containing molecules are
organic
• CO2
Common biochemical's and their
structure
Category
Subcategory
Example molecules
Carbohydrates
Monosaccharides
Glucose, galactose, fructose
Disaccharides
Maltose, lactose, sucrose
Polysaccharides
Starch, glycogen, cellulose
Protein
Enzymes, antibodies
Lipids
Triglycerides, phospholipids
Nucleic acids
DNA, RNA
Molecule
Amino Acids
Glucose
Ribose
Structure
Molecule
Fatty Acids
Structure
Functions of carbohydrates in animals
and plants
• Carbohydrates exist in different sizes
• Monosaccharides
• Dissaccharides
• Polysacchrides
Functions of carbohydrates in animals
and plants
• All of these carbohydrates serve many
functions in living organisms
• Animals:
Name
Type
One Function
Glucose
Monosaccharide
Chemical fuel for cell
respiration
Lactose
Disaccharide
Makes up some of the
solutes in milk
Glycogen
Polysaccharides
Stores glucose in liver
and muscles
Functions of carbohydrates in animals
and plants
• Plants
Name
Type
One Function
Fructose
Monosaccharide
Found in many fruits (makes them
sweet)
Sucrose
Disaccharide
Often transported from leaves of
plants to other locations in plants
by vascular tissue
Cellulose
Polysaccharide
One of the primary components of
plant cell walls
Role of Lipids
• Lipids are biochemically important molecules that
serve many functions.
• Triglyceride lipids
– Solid form as fats
– Liquid form as oils
• If you eat more food than you burn, your body
will store much of the excess as fat in adipose
cells
– Adipose cells get smaller or larger depending on how
much lipids is being stored
Role of Lipids
• Lipids are very efficient molecules for storing
energy
– Glycogen is a carbohydrate used by animals to
store energy
– Starch is a carbohydrates used by plants to store
energy
• Equal mass of carbohydrates and lipids, the
lipid stores approximately twice as much
chemical energy as the carbohydrates
Role of Lipids
• Lipids are also important for thermal
insulation
– Blubber!!!
Condensation and hydrolysis reactions
• A condensation reaction is responsible for
building large molecules. An enzyme catalyzes
the reaction between alcohol groups on
adjacent monomer units (eg. glucose). This
results in the production of a polymer and a
molecule of water.
• A-H + B-OH --> A-B + H2O
Condensation and hydrolysis reactions
• A hydrolysis reaction is responsible for
breaking down large molecules (eg.
digestion). An enzyme weakens the bond
between two parts of a polymer, allowing for
the insertion of a water molecule into the
bond. This results in the production of
monomers.
• A-B + H2O --> A-H + B-OH
Condensation and hydrolysis reactions
• Digesting Food
– Food are chemically digested in your alimentary
canal
• Digestive enzymes that accomplish this are hydrolysing
enzymes
• Each reaction requires a molecule of water as a
reactant