| The structure of biological membranes makes them fluid and dynamic. |
| Understandings: |
Nature of science: |
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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 is a component of animal cell membranes.
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Using models as representations of the real world—there are alternative models of membrane structure. (1.11) |
| Applications : |
Guidance: |
| Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes. |
Amphipathic phospholipids have hydrophilic and hydrophobic properties.
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 glycoproteins.
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| Skill: |
Theory of Knowledge |
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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.
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Falsification of theories with one theory being superseded by another—evidence falsified the Davson-Danielli model. (1.9) |
