Bio1 Unit 4: Membrane dynamics

lipid rafts

specific lipids found in these patches

fluidity buffer

resists change in membrane fluidity

diffusion

movement of particles so they spread out into the available space

osmosis

diffusion of free water across a selectively permeable membrane

Tonicity

the ability of a surrounding solution to cause a cell to gain or lose water

what are the three types of solutions?

hypotonic, isotonic, and hypertonic

Turgor pressure

Pressure that opposes further water uptake

turgid

cell that is very firm

Plasmolysis

when the plasma membrane pulls away from the cell wall at multiple faces

osmoregulation

the control of solute concentrations and water balance

Peripheral protein

Appendages loosely bound to the surface of the membrane

integral protein

penetrate the hydrophobic interior of the lipid bilayer

transmembrane proteins

span the entire membrane

cell-cell recognition

cell’s ability to distinguish one type of neighbouring cell from another

glycolipid

carbohydrates bonded covalently to lipids

glycoproteins

carbohydrates bonded covalently to proteins

channel proteins

hydrophilic channel that molecules and atomic ions use as a tunnel

carrier proteins

change shape as they shuttle molecular passengers across the membrane

Aquaporin

they allow up to 3 billion water molecules (10 at a time) per second through the membrane

Passive transport

diffusion of a substance across a membrane with no energy investment

dynamic equilibrium

after diffusion there are equal concentrations of the molecule on both sides of the membrane

facilitated transport/diffusion

passive transport through membrane transport proteins (down a concentration gradient)

active transport

uses energy to move solutes against their concentration gradients

voltage

electrical potential energy, a separation of opposite charges

membrane potential

voltage across a membrane (-5 to -200mV)

electrochemical gradient

combination of two forces driving diffusion of ions across a membrane

electrogenic pump

transport protein that generates voltage across a membrane

Cotransport

groups the downhill diffusion of a solute to the transport of a second substance against its concentration gradient