Biomolecules
Name: ______________________________
Biomolecules
Biomolecules are large molecules made up of smaller sub-units that are bonded
together in different ways. Large compounds made of many sub-units are called
polymers. The sub-units are called monomers.
The four main classes of biomolecules are: carbohydrates, proteins, lipids and
nucleic acids.
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Carbohydrates
Type Example Function Structure
Monosaccharides Glucose Energy source in
plant and animal
cell
Disaccharides Maltose Important for
digestion.
Polysaccharides Starch Form of energy
storage in plants
Glycogen Form of energy
storage in
animals
Cellulose Structural
carbohydrate in
plant cell walls
1. Identify the three elements found in carbohydrates.
2. Consider the carbohydrates glucose, starch, cellulose and glycogen. In what ways
are these compounds similar and in what ways are they different?
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Proteins
Monomer: Amino acid
Polymer: Polypeptide chain
Proteins are organic molecules that form muscles, transport oxygen and act as
hormones and enzymes. The building block or monomer of proteins is the amino
acid. Proteins are made of amino acids linked by a peptide bond. When groups of
amino acids are joined together, a polypeptide chain is formed.
There are about 20 different amino acids. Below is the basic structure of an amino
acid:
The difference between the 20 amino acids is the R group.
Example of Amino Acid Structures:
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1. Draw the structure of the monomer of a protein.
2. What type of bond links amino acids together?
3. What makes each of the 20 amino acids unique?
4. What elements are found in an amino acid (excluding the R group)?
5. Identify four functions of proteins.
Lipids
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Lipids are oily, greasy or waxy in consistency
Lipids are relatively insoluble in water (they don’t dissolve in water)
Monomers of lipids: triglycerides and phospholipids.
Lipid Structure: Monomers
Neutral Fat
Most abundant lipids in living things
A glycerol head with three fatty acid
tails
Also known as a triglyceride
Phospholipid
Phosphate and glycerol head which
is hydrophilic which means ‘water-
loving’
There are two fatty acid tails which
are hydrophobic or ‘water-repellent’
Phospholipids are the basic
component of the cell membrane
1. Describe the basic structure of a phospholipid.
2. Describe the difference between hydrophobic and hydrophilic in the context of a
phospholipid.
Nucleic Acids
Monomer: Nucleotide
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Polymer: Deoxyribonucleic acid OR ribonucleic acid
Monomer Nitrogenous Bases Diagram
Adenine
Thymine
Cytosine
DNA Nucleotide Guanine
Adenine
Uracil
Cytosine
RNA Nucleotide Guanine
1. Draw a diagram of a DNA monomer containing the nitrogenous base cytosine.
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High-Energy Compounds
ATP is a nucleotide that transports chemical energy within cells for metabolism.
It consists of an adenine linked to ribose sugar and 3 phosphate groups
When losing its energy, ATP loses a phosphate group to become ADP
3 phosphate groups
Adenine
Ribose Sugar
Adenine 2 phosphate groups
Ribose Sugar Inorganic phosphate
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Summary
