Bio102: Introduction to Cell Biology and Genetics
Fluid Mosaic Model
Key Terms:
Fluid Mosaic Model
Protein
Amino Acid
Peptide Bond
Amino Terminus
Carboxyl Terminus
Hydrolysis Reaction
Condensation Reaction
Denaturation
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure
Hydrogen bonding
van der Waals interactions
Ionic interactions
Disulfide bridges
Transmembrane domain
Key Questions:
 How is a membrane “fluid”? What types of movement happen and which types don’t happen?
 How are individual amino acids different from each other? How are they the same? How are
they connected?
 How is a protein’s three-dimensional structure determined? Why is that structure important?
How can that structure be altered?
 How are proteins integrated into a lipid bilayer?
Lecture Outline:
Fluid Mosaic Model
Proteins within the lipid bilayer
Proteins are polymers of amino acids
Structure of amino acids
side chains are highly variable
Peptide bonds to connect amino acids
directionality of the polymer – amino terminus is front, carboxyl terminus is back
Primary structure is the sequence of the amino acids
Secondary structure is 3D shape over short distances
Tertiary structure is 3D shape over the entire protein
Quaternary structure is the interaction of multiple proteins with each other
Secondary-Quaternary structures are determined by noncovalent interactions
hydrogen bonding
van der Waals interactions
ionic interactions
disulfide bridges (covalent)
Denaturation of proteins destroys their secondary – quaternary structure
Sequence determines structure. Structure determines function.
Membrane Proteins
hydrophobic parts of the protein fit into the hydrophobic environment
hydrophillic parts of the protein stick out into the cytosol or outside of cell
Proteins and lipids are free to move laterally within the membrane