Biology Chapter 7

when a plasma membrane allows some substances to cross it more easily than others

both hydrophobic and hydrophilic regions (phospholipids are this)

integral proteins that span the membrane

allow passage of hydrophilic substances across the membrane

formed by carbohydrates being covalently bonded to proteins

channel proteins that facilitate the passage of water

the tendency for molecules to spread out evenly into the available space

diffusion of a substance across a membrane (no energy investment)

diffusion of water across a selectively permeable membrane

solute concentration of the environment is the same as that inside the cell

solute concentration of the environment is greater than that inside the cell

solute concentration of the environment is less than that inside the cell

when in a hypertonic environment plant cells lose water and the membrane pulls away from the wall (this is usually lethal)

moving a substance up a concentration gradient

active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process

cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane

movement of specific molecules into a cell by the inward budding of vesicles containing proteins with receptor cites specific to the molecules being taken in; enables a cell to aquire bulk quantities of specific substances