class notes 4:cellular transport and the plasma membrane
DESCRIPTION
II. Other molecules of the cell membrane A. Cholesterol -strengthens the membrane. B. Transport proteins-like tunnels allowing certain substances in and out. C. Carbohydrates- allow cells to identify eachother.TRANSCRIPT
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Class Notes 4:Cellular Transport and the Plasma Membrane
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I. Structure of the Plasma Membrane
A. All cells have a plasma membrane. It is a PHOSPHOLIPID BILAYER
B. A phospholipid is a molecule with 3 parts:
1. Polar phosphate2. Glycerol3. Non- polar fatty acid tail
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II. Other molecules of the cell membrane
A. Cholesterol -strengthens the membrane.
B. Transport proteins-like tunnels allowing certain substances in and out.
C. Carbohydrates- allow cells to identify eachother.
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III. Methods of cellular transport:
A. The membrane has SELECTIVE PERMEABILITY- some but not all materials can cross.
B. Materials can move in and out of the cell in the following ways:
1. Passive Transport = no energy requireda. Diffusion
b. Facilitated diffusion2. Active Transport= energy required3. Endocytosis4. Exocytosis
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IV. Passive transport
A. Very small molecules like 02 can pass right through the plasma membrane by diffusion.
B. Facilitated diffusion allows larger particles to go through transport proteins.
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V. Active Transport
A. Movement of materials through a membrane against a concentration gradient is called Active Transport and requires energy.
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B. Endocytosis
Some cells can take in large molecules, groups of molecules, or even whole cells = ENDOCYTOSIS
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C. Exocytosis
1. Exocytosis is the explosion or secretion of materials from the cell (wastes, hormones)
2. Endocytosis and Exocytosis require energy!
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Summary
Describe the structure of the plasma membrane. How do molecules get in and out? What is the difference between active and passive transport?