1.3 Membrane structure

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1.3 Membrane structure

1.3 Membrane structure

1.3 Concept  Mapping

1.3 Knowledge Control

1.3 Presentation

1.3 Video/ Animation 

1.3 Past Paper  Questions

1.3.1 The structure of biological membranes makes them fluid and dynamic.Essential idea:

Nature of science:


1.3.2.Using models as representations of the real world—there are alternative models of membrane structure. (1.11)


1.3.3 Falsification of theories with one theory being superseded by another—evidence falsified the Davson-Danielli model. (1.9)




1.3.4 Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.

Membrane structure with animations

Construction of the Cell Membrane-learning activity

Construction of cell membrane


1.3.5 Membrane proteins are diverse in terms of structure, position in the membrane and function.

Membrane proteins

1.3.6 Cholesterol is a component of animal cell membranes.






1.3.7 Application: Cholesterol in mammalian membranes reduces membrane

fluidity and permeability to some solutes.


Membrane fluidity




1.3.8 Drawing of the fluid mosaic model


1.3.9 Analysis of evidence from electron microscopy that led to the proposal of the Davson-Danielli model.


1.3.10 1.3.10 Analysis of the falsification of the Davson-Danielli model that led to the Singer-Nicolson model.




1.3.11 Amphipathic phospholipids have hydrophilic and hydrophobic properties.


1.3.12 Drawings of the fluid mosaic model of membrane structure can be two

dimensional rather than three dimensional. Individual phospholipid

molecules should be shown using the symbol of a circle with two parallel

lines attached. A range of membrane proteins should be shown including



Theory of knowledge:


1.3.13 The explanation of the structure of the plasma membrane has

changed over the years as new evidence and ways of analysis have

come to light. Under what circumstances is it important to learn

about theories that were later discredited?




Syllabus and cross-curricular links:


Topic 2.3 Carbohydrates and lipids

Topic 2.6 Structure of DNA and RNA



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