Bio Ch. 7

amphipathic

hydrophobic and hydrophilic (ex. phospholipids)

fluid mosaic model

depicts cell membrane as a mosaic of protein molecules in a fluid phospholipid bilayer

peripheral proteins

bound to membrane surface

transmembrane proteins

integral proteins that span the membrane

integral proteins

proteins that penetrate the hydrophobic membrane core

glycolipids

carbs bonded to lipids

carrier proteins

bind to molecules & change shape to cross the membrane

diffusion

movement of particles to spread evenly into available space (passive)

concentration gradient

region where the density of a chemical substance increases/decreases

osmosis

diffusion of free water across the selectively permeable membrane

tonicity

ability of a surrounding solution to cause a cell to gain/lose water

osmoregulation

the control of solute regulation & water balance

plasmolysis

plant cell in hypertonic state —> membrane pulls away from cell wall in multiple locations

facilitated diffusion

transport proteins speed up passive movement across a membrane

ion channels

facilitate ion transport

chemical stimulus

binding of a specific substance to the protein that triggers changes in activity

membrane potential

chemical voltage across a membrane (distribution of +/- ions)

electrochemical gradient

chemical force (ion’s conc. gradient) + electrical force (effect of membrane potential on movement)

electrogenic pump

transport protein that generates voltage across a membrane & stores energy for cellular work

cotransport

active transport indirectly drives transport of other substances

exocytosis

transport vesicles fuse to the cell membrane & empty contents outside the cell

endocytosis

cell membrane forms a pocket around transport material & engulfs

phagocytosis (eating)

form of endocytosis where pseudopodia extend & pack food into a vacuole —> digested by lysosome

pinocytosis (drinking)

nonspecific form of endocytosis where extracellular fluid is “gulped” into vesicles

receptor-mediated endocytosis

vesicles are formed when solutes bind to receptors