The movement of one specific ion or molecule across the membrane.
Symport
The movement of two different ions or molecules in the same direction across the plasma membrane
Antiport
The movement of two different ions or molecules in opposite directions across the plasma membrane
ATP-powered pumps
Transport proteins that move specific ions and molecules from one side of the plasma membrane to the other
Receptor proteins
Proteins or glycoproteins in the plasma membrane with an exposed receptor site on the outer cell surface.
G protein complex
Acts as an intermediate between a receptor and other cellular proteins
The G protein complex consists of which three proteins?
Alpha, beta, and gamma
Enzymes
Membrane proteins that can catalyze chemical reactions on either the inner or the outer surface of the plasma membrane
Selectively permeable
The plasma membrane allows only certain substances to pass through it
Which 4 ways do molecule and ions pass through the plasma membrane?
Directly through the phospholipid membrane
Membrane channels
Transport proteins
Vesicles
Diffusion
The movement of solutes from an area of higher solute concentration to an area of lower solute concentration
Concentration gradient
The concentration difference between two points divided by the distance between the two points
Osmosis
The diffusion of water across a selectively permeable membrane.
Aquaporins
Water channel proteins that increase membrane permeability to water in some cell types
Osmotic Pressure
The force required to prevent the movement of water by osmosis across a selectively permeable membrane
Isosmotic
Solutions with the same concentration of solute particles that have the same osmotic pressure
Hyperosmotic
A solution that has a greater concentration of solute particle and therefore a greater osmotic pressure
Hyposmotic
A dilute solution with the lower osmotic pressure
Crenation
When water moves by osmosis from the cell into the hypertonic solution causing the cell to shrink
Filtration
When a partition containing small holes is placed in a stream of moving liquid.
Mediated transport
The process by which transport proteins mediate the movement of large water-soluble molecules
Specificity
Each transport protein binds to and transports only a single type of molecule or ion
Competition
The result of similar molecules binding to the transport protein
Saturation
The rate of movement of molecules across the membrane is limited by the number of available transport proteins
Facilitated diffusion
A carrier-mediated or channel-mediated process that moves substances into or out of cells from a higher to a lower concentration
Active transport
A mediated transport process that requires energy provided by ATP
Secondary active transport
Involves the active transport of an ion out of a cell
Endocytosis
The internalization of substances
Vesicle
A membrane-bound sac found within the cytoplasm of a cell
Phagocytosis
(cell eating)
Applies to endocytosis when solid particles are ingested and phagocytic vesicles are formed
Pinocytosis
(cell drinking)
Smaller vesicles are formed and molecules dissolve in liquid
Receptor-mediated endocytosis
The plasma membrane contains specific receptor molecules that recognize certain substances and allow them to be transported into the cell by phagocytosis or pinocytosis.
Exocytosis
The membrane of the vesicle fuses with the plasma membrane and the content of the vesicle is expelled from the cell