Cell Membrane Structure
• The cell membrane functions to:
• _____________________________ between the internal and external environment of the cell.
• _________________ what is allowed to enter and exit the cells internal environment.
• Provides protection and support.
Draw the phospholipid bilayer
Fluid mosaic model
• The fluid mosaic model was developed to explain how the cell membrane is structured.
• Phospholipid bilayer with proteins floating in and on it.
Proteins in the cell membrane
• Proteins have ________________________________________, this way they can span the membrane
• There are both__________________(on the outside) proteins and____________________(part of the membrane) proteins
• Some proteins within the membrane have carbohydrates attached. These are called
____________________________
• Lipids in the bilayer can also have carbohydrates attached. These are called
_________________________.
• Carbohydrate chains only occur on the___________________________________ and function to identify the cell
• Proteins perform several functions in the cell membrane:
• Channel proteins: _______________________________________________
_________________________________

• Carrier protein: ___________________________________________________
_____________________________________________________
• Recognition proteins: allow the cell to be recognized by other cells
(glycoproteins)
• Ex. Tissue rejection in organ donation
• Receptor protein: have a special shape to be able to bind with other molecules
• Enzymatic proteins: carry out metabolic reactions
Selective Permeability
• Permeable- the ability to pass through a membrane
• The cell membrane is a __________________________________________ membrane.
• This means that it allows some things through and prevents others from entering or exiting.
• Transport across a membrane is classified as either ______________________________
• Why would cells be selectively permeable?
________________________________________________________________________
________________________________________________________________________
Draw a diagram of what happens to a solute trying to cross a selectively permeable membrane where one is permeable and the other is impermeable.
• Solution- a liquid with one or more substances dissolved in it
• Solvent- the liquid that the solute is dissolved in
• Solute- the substance dissolved in a solution
• Concentration- how strong it is… the solute/volume (percentage)
Transport through the Membrane
Diffusion
• Particles moving from an area of _________________________________________
____________________________________________________________________
• Diffusion refers to the process by which the molecules of two different substances intermingle (mix) as a result of their kinetic energy of random motion.

• Does not use a _________________________________
• Moves with the_________________________________________(high to low)
• Does not require additional cell energy
• Passive
• Examples: ____________________________________________________________
Draw diffusion
• The rate of diffusion can be increased by:
• _____________________________
• _____________________________
• _____________________________
• _____________________________
Osmosis
• The ____________________________________________ from the area of greater concentration of water to the area of lesser concentration of water until it is evenly distributed
• Must be across a _______________________________________________________
• Water passes through _____________________________________________
• Osmotic pressure can work against physical pressure
Draw Osmosis

Facilitated Transport
• An assisted form of _________________________
• Moves molecules that would not be able to cross the membrane alone
• Moves toward the ________________________________________
• Requires _______________________________
• No energy is needed
Draw facilitated transport