1.3
Membrane structure
Nature of science
Using models as representations of the real world—there are alternative models of membrane structure. (1.11)
Falsification of theories with one theory being superseded by another—evidence falsified the Davson-Danielli model. (1.9)
Understandings
Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.
Membrane proteins are diverse in terms of structure, position in the membrane and function.
Cholesterol is a component of animal cell membranes.
Application
Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes.
Skills
Drawing of the fluid mosaic model.
Analysis of evidence from electron microscopy that led to the proposal of the Davson-Danielli model.
Analysis of the falsification of the Davson-Danielli model that led to the Singer-Nicolson model.
DBQs
Falsification of the plasma membrane
