BIOB10H3 Lecture Notes - Lecture 5: Fluid Mosaic Model, Lipid Bilayer, James Danielli
21 May 2018
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Lecture 5
Plasma Membrane:
Structure and Function
Functions of the Plasma Membrane:
1. Compartmentalization
- encloses and protects contents of the cell
2) Scaffold for Biochemical Activities
- for enzyme and signaling proteins
3) Provide a Selectively Permeable Barrier
4) Transporting Solutes
- machinery for moving sugars, amino acids and ions
5) Responding to External Signals
6) Intercellular Interaction
Structure of the Plasma Membrane:
History of Plasma Membrane Studies
1) Overto ’s
• added dissolved solutes to cells
• only lipid soluble molecules could enter cells
➔
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History of Plasma Membrane Studies
1) Oerto ’s
2) Gorter and Grendal (1925)
• lysed red blood cells
• spread lipid over water
• measured twice as much
lipid as the predicted surface area
➔
History of Plasma Membrane Studies
1. Oerto ’s
2. Gorter and Grendal (1925)
3. Daielli ad Daso ’s
• Proposed proteins were in lipid bilayer
➔ globular proteins lining surfaces and lining channels to form pores
History of Plasma Membrane Studies
Oerto ’s
2) Gorter and Grendal (1925)
Daielli ad Daso ’s
Eletro Mirosop ’s
➔
5) Singer and Nicolson (1972)
• Membrane is fluid
• Individual proteins can penetrate bilayer
➔ Fluid Mosai Model
Fluid Mosaic Model
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Composition of the Plasma Membrane:
1. Membrane lipids
2. Membrane Carbohydrates
3. Membrane Proteins
1. Membrane Lipids
a. Phospholipids
b. Sphingolipids
c. Cholesterol
a) Phospholipids
b) Sphingolipids
- Single fatty acid chain
- Attached to a sphingosine group
- Sugar added (glycolipid)
➔eg. cerebroside
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Document Summary
Encloses and protects contents of the cell: scaffold for biochemical activities for enzyme and signaling proteins, provide a selectively permeable barrier, transporting solutes, responding to external signals, intercellular interaction machinery for moving sugars, amino acids and ions. History of plasma membrane studies: overto(cid:374) (cid:894)(cid:1005)(cid:1012)(cid:1013)(cid:1004)"s(cid:895, added dissolved solutes to cells, only lipid soluble molecules could enter cells. History of plasma membrane studies lysed red blood cells: o(cid:448)erto(cid:374) (cid:894)(cid:1005)(cid:1012)(cid:1013)(cid:1004)"s(cid:895, gorter and grendal (1925, spread lipid over water, measured twice as much lipid as the predicted surface area. History of plasma membrane studies: o(cid:448)erto(cid:374) (cid:894)(cid:1005)(cid:1012)(cid:1013)(cid:1004)"s(cid:895, gorter and grendal (1925, da(cid:374)ielli a(cid:374)d da(cid:448)so(cid:374) (cid:894)(cid:1005)(cid:1013)(cid:1007)(cid:1004)"s(cid:895, proposed proteins were in lipid bilayer. Globular proteins lining surfaces and lining channels to form pores. History of plasma membrane studies (cid:1005)(cid:895) o(cid:448)erto(cid:374) (cid:894)(cid:1005)(cid:1012)(cid:1013)(cid:1004)"s(cid:895: gorter and grendal (1925) (cid:1007)(cid:895) da(cid:374)ielli a(cid:374)d da(cid:448)so(cid:374) (cid:894)(cid:1005)(cid:1013)(cid:1007)(cid:1004)"s(cid:895) (cid:1008)(cid:895) ele(cid:272)tro(cid:374) mi(cid:272)ros(cid:272)op(cid:455) (cid:894)(cid:1005)(cid:1013)(cid:1009)(cid:1004)"s(cid:895, singer and nicolson (1972, membrane is fluid.
