BCMB 201: Structure and
Function of Biomolecules
Module 1: Biomolecules
Based on Lehninger Principles of
Biochemistry (Chapter 1)
Foundations of Biochemistry
• Biochemistry studies the chemical processes
underlying life.
• Living systems obey the same chemical laws as
non‐living systems.
• Key principle: Structure determines function.
What Are Biomolecules?
• Biomolecules are organic molecules produced
by living organisms.
• Major classes: carbohydrates, lipids, proteins,
nucleic acids.
• Built primarily from C, H, O, N, P, S.
Monomers and Polymers
• Monomers: small building blocks (e.g., amino
acids, nucleotides).
• Polymers: large molecules formed by linking
monomers.
• Polymerization often involves condensation
reactions.
Macromolecules
• Macromolecules are large biological polymers.
• Examples:
• ‐ Proteins (polypeptides)
• ‐ Polysaccharides
• ‐ Nucleic acids
Supramolecular Assemblies
• Supramolecules are complexes of
macromolecules.
• Held together by noncovalent interactions.
• Examples: membranes, ribosomes,
cytoskeleton.
Noncovalent Interactions
• Weak individually but strong collectively.
• Types:
• ‐ Hydrogen bonds
• ‐ Ionic interactions
• ‐ Hydrophobic interactions
• ‐ van der Waals forces
Importance of Water
• Water is the solvent of life.
• Polar molecule capable of hydrogen bonding.
• Influences biomolecular structure and
interactions.
Chemical Bonds in Biomolecules
• Covalent bonds: strong, stable (C–C, C–N, C–
O).
• Noncovalent bonds: reversible and dynamic.
• Both are essential for biological function.
pH and Biological Systems
• pH measures hydrogen ion concentration.
• Most cells function near neutral pH.
• pH affects ionization and structure of
biomolecules.
Functional Groups
• Common functional groups:
• ‐ Hydroxyl
• ‐ Carboxyl
• ‐ Amino
• ‐ Phosphate
• They determine chemical reactivity.
Chemical Logic of Life
• Carbon forms stable covalent bonds.
• Biological molecules are information‐rich.
• Molecular interactions drive biological
processes.
Summary
• Biomolecules are the chemical foundation of
life.
• Structure, bonding, and interactions
determine function.
• This framework underlies all later
biochemistry topics.