The Cell Membrane aka Plasma Membrane Function holds
The Cell Membrane aka – Plasma Membrane
Function: holds cell together and acts as a barrier that allows only certain substances to cross it. Structure: Phospholipid Bilayer – hydrophobic surface prevents water and substances dissolved in water from crossing the membrane Proteins – serve to identify cell, transport substances, hook cells together, and speed up chemical reactions within the cell Cholesterol - helps stabilize the phospholipids at body temperature and keeps the membrane “fluid” at low temperatures Carbohydrates – serve to identify or “tag” the cell
The Fluid Mosaic Model
Membrane Protein Functions
Endomembrane System
Transport Across the Plasma Membrane Diffusion – process by which non-charged molecules small enough to cross the membrane move from a high to low concentration. Example: O 2 diffuses across a red blood cell’s membrane Osmosis – process by which water moves across a membrane from high to low concentration of solute
Tonicity
Label the following diagrams
Water Potential ( ) • measured in Efree/mol H 2 O • Can be calculated using: = P + S P = Pressure potential S = Solute potential
= 0 in pure water in an open beaker because both P and S are equal to zero When solute is added to a solution, it lowers S and therefore decreases .
S = i. CRT i = the ionization constant C = molar concentration of a solution R = pressure constant 0. 0831 L bars/mol K T = temerature in Kelvin (273+ °C) i = the number of particles a compound will produce in water (ex. Na+Cl-; i = 2, glucose; i = 1)
Facilitated Diffusion • movement of molecules across a membrane by the aid of a membrane -protein, where the protein expends no energy (passive transport)
Passive Transport Animation
Overview of Passive Transport Small charged molecules Like O 2 and CO 2 Like glucose H 2 O
Active Transport • process by which a molecule moves across the plasma membrane by the aid of a membraneprotein where the protein expends energy
Sodium. Potassium Pump
Exocytosis & Endocytosis • process by which bulky materials such as proteins are transported across a plasma membrane
Hypercholesterolemia Since blood cells deficient in LDL receptors cannot take in LDL cholesterol it deposits on the walls of blood vessels.
Exo and Endocytosis in Cell Communication
How Cell Signaling Works
How Cell Signaling Works
How Cell Signaling Works
Specific Example
Testosterone Signaling
In partners or groups of 3… Create a flow chart showing the different types of membrane transport
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