Topic 1.3: Membrane Structure
Essential Idea: The structure of biological membranes makes them fluid and dynamic.
At SHS, Topic 1.3 is taught in the following class unit(s):
1.3.U1 Phospholipids form bilayers in water due to the amphipathic properties of phospholipid molecules.
- Draw a simplified diagram of the structure of the phospholipid, including a phosphate-glycerol head and two fatty acid tails.
- Define hydrophilic and hydrophobic.
- Define amphipathic and outline the amphipathic properties of phospholipids.
- Explain why phospholipids form bilayers in water, with reference to hydrophilic phosphate heads and two hydrophobic hydrocarbon tails.
1.3.U2 Membrane proteins are diverse in terms of structure, position in the membranes and function.
- State the primary function of the cell membrane.
- Contrast the structure of integral and peripheral proteins.
- List at least four functions (with example) of membrane bound proteins.
- Contrast the two types of transport proteins: pumps and channels.
1.3.U3 Cholesterol is a component of animal cell membranes.
- Identify the structure of cholesterol in molecular diagrams.
- Describe the structural placement of cholesterol within the cell membrane.
1.3.A1 Cholesterol in mammalian membranes reduces membrane fluidity and permeability to some solutes.
- Describe the function of cholesterol molecules in the cell membrane.
1.3.S1 Drawing of the fluid mosaic model.
- Draw and label the structure of membranes. Include:
- Phospholipid bilayer
- Integral proteins shown spanning the membrane
- Peripheral proteins on membrane surface
- Protein channels with a pore
- Glycoproteins with a carbohydrate side chain
- Cholesterol between phospholipids in the hydrophobic region
- An indication of thickness (10nm)
1.3.S2 Analysis of evidence from electron microscopy that led to the proposal of the Davson-Danielli model.
- Describe the observations and conclusions drawn by Davson and Danielli in discovering the structure of cell membranes.
1.3.S3 Analysis of the falsification of the Davson-Danielli model that led to the Singer-Nicolson model.
- Describe conclusions about cell membrane structure drawn from freeze-etched electron micrograph images of the cell membrane.
- Describe conclusions about cell membrane structure drawn from cell fusion experiments.
- Describe conclusions about cell membrane structure drawn from improvements in techniques for determining the structure of membrane proteins.
- Compare the Davson-Danielli model of membrane structure with the Singer-Nicolson model.
1.3.NOS1 Using models as representations of the real world-there are alternative models of membrane structures.
- Explain what models are and their purposes in science.
- Describe the observations and conclusions drawn by Gorter and Grendel in discovering the structure of cell membranes.
1.3.NOS2 Falsification of theories with one theory being superseded by another-evidence falsified the Davson-Danielli model.
- Describe why the understanding of cell membrane structure has changed over time.
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Cell Membrane Structure (unit 7)