Membrane Transport Flashcards
Selective Permeability (Lipid Bilayer)
Non-Polar: Easily crossed as they are hydrophobic
Polar: Difficultly crossing as they are hydrophilic
Charged: Passing is prevent as they have a sphere of water around it and the tails are hydrophobic
Large: Don’t fit through pores
Selective Permeability (Transport Proteins)
Channel: Hydrophilic channel that allows for polar and charged molecules to pass through
Carrier: Holds onto certain molecules and changes shape in a way that shuttles molecules across membrane
Directional Movement
Molecules in substance are in constant random motion and disperse from areas of high concentration to low
- Molecules will disperse till they reach a state of equilibrium
- Factors that affect rate of diffusion: concentration gradient, temperature, distance, area of membrane, permeability of membrane
Passive Transport
Diffusion of a substance across membrane with no energy investment; no energy investment as substance moves down concentration gradient
Passive Transport (Osmosis)
Diffusion of water; Balances concentration gradient of solute by changing the volume of solute
Hypotonic- [Solute]Out<[Solute]In; H2O goes in=Swells
Isotonic- [Solute]Out= [Solute]In
Hypertonic- [Solute]Out> [Solute]In; H2O goes out=Shrivels
Facilitated Diffusion
Diffusion with the help of transport proteins
-Provides hydrophilic (polar) passageways that allow small, polar ions and molecules to cross
Active Transport
Uses energy to move solutes against concentration gradient
-Uses carrier proteins
Bulk Transport
Transport of large molecules
-Molecules must be packaged in vesicles or vacuoles (rearrangement of plasma membrane is required to form vesicles)
-Endocytosis- Cell takes in material by forming vesicles
-Exocytosis- Cell exports material by fusing vesicles with plasma membrane