The Cell Membrane Flashcards
(17 cards)
Plasma Membrane Structure
Physical barrier
Gateway for exchange
Communication
Cell structure
Phospholipid Bilayer
Polar Choline head
Non-polar, fatty acid tails that create barrier for flow
Contains cholesterol to prevent crystallization, keeps it fluid
Glycocalyx
Glycoproteins on surface of cell
For cell identity, cell orientation, barrier for growth
Membrane Proteins
Ions channels- move calcium, sodium, etc Carriers- glucose shuttled in Receptor sites- tells to release hormone Enzymes-control cell reaction Pores-water Structure Cell adhesion- cell junctions Signal transduction
Membrane Permeability
Selectively permeable
Permeable to small uncharged, non-polar(lipid soluble) molecules
Transmembrane proteins move polar molecules
Macromolecules use vesicles
Movement across Membrane- Passive
Requires no energy
Simple diffusion, facilitated diffusion, osmosis
Movement across Membrane- Active
Uses ATP
Active transport, vesicular transport
Simple Diffusion
Net diffusion from high to low concentration
Small molecules (oxygen and carbon dioxide) and steroids
Temperature, concentration gradient, diffusion distance, mass of substance can increase rate
Osmosis
Net diffusion of water down its own concentration gradient
Pulled by non-diffusible particles
Moves from hypotonic to hypertonic
Tonicity
Number of non-diffusible particles
Isotonic
Solutions are the same
No net osmosis
Hypotonic
Fewer non-diffusible particles
Hypertonic
More non-diffusible particles
Facilitated Membrane Transport
Plasma proteins- pores, channels, carriers
Substance moves along concentration gradient
Active Transport
Against concentration gradient
Requires Energy (ATP runs pump)
Must use carrier
Co-transport
Creating a concentration gradient so when it comes back into cell it brings another molecule with it (free ride)
Vesicle Transport
Endocytosis and Exocytosis
