5.3 active transport Flashcards
concentration gradient
substance move from high concentration to low concentration
active transport
substances move into the cell against its concentration gradient; substance’s concentration inside the cell is greater than its concentration in the extracellular fluid; requires ATP; moves small-molecular weight materials through membrane; transports larger molecules
electrical gradient
difference of charge across the plasma membrane; ions move into and out of cell
electrochemical gradient-sodium
cell has lower concentration of Na+ than extracellular fluid; concentration gradient AND electrical gradient drive Na+ into the negatively charged interior
eletrochemical gradient-potassium
cell has higher concentrations of K+ than extracellular fluid; concentration gradient drives K+ OUT of cell; electrical gradient drive K+ into the cell
pumps
active transport mechanisms that work against electrochemical gradients to move substances against a concentration OR electrochemical gradient; requires ATP generated through the cell’s metabolism
transporters
facilitate movement into and out of cells in active transport; three kinds; transport small, uncharged organic molecules like glucose
uniporter
carries one specific ion or molecule
syporter
carries two different ions or molecules in the same direction
antiporter
carries two different ions or molecules in different directions
active transport mechanisms
primary active transport and secondary active transport; both transport small molecular weight material and small molecules
primary active transport
moves ions across a membrane and creates a difference in charge across that membrane; requires ATP
secondary active transport
the movement of material due to the electrochemical gradient established by primary active transport; does not require ATP
sodium potassium pump (primary active transport “step 1”)
moves K into the cell while moving Na+ out at the same time (2:3); maintains the electrochemical gradient and correct concentrations of Na+ and K+ in living cells; interior of cell is more negative than the exterior
electrogenic pump
a pump that creates a charge imbalance; important for secondary process
sodium potassium pump (secondary active transport “step 2”)
Uses the kinetic energy of the sodium ions to bring other compounds against their concentration gradient into the cell; the potential energy that accumulates in the stored hydrogen ions translates into kinetic energy
bulk transport
used for molecules too large to be moved by transport proteins; vesicles take them into or out of the cell
endocytosis
active transport; moves large molecules into the cell; the cell’s plasma membrane forms a pocket around the target particle then pinches off resulting in a vesicle with the particles inside
phagocytosis (type of endocytosis)
process by which a cell takes in large particles, such as other cells, bacteria or food particles; merges with a lysosome to release the particles
pinocytosis (type of endocytosis)
vesicles form around a liquid or very small particles which the cell needs from the extracellular fluid; much smaller vesicle; doesnt need to merge with a lysosome
potocytosis
variation of pinocytosis; brings small molecules into the cell and transports them through the cell to the other side (transcytosis); vesicles smaller than ones in pinocytosis
receptor-mediated endocytosis (type of endocytosis)
molecules bind to specific receptor proteins in an embedded pit in the plasma membrane, when enough molecules accumulate the pit deepens, seals and is incorporated into the cell
exocytosis
expels material from the cell into the extracellular fluid; waste material is enveloped in a membrane and fuses with the plasma membrane’s interior; then fusion opens the envelope on the cell’s exterior and the waste material expels into the extracellular space
diffusion (active/passive)
passive
osmosis (active/passive)
passive
facilitated diffusion (active/passive)
passive
primary active transport (active/passive)
active
secondary active transport (active/passive)
active
phagocytosis (active/passive)
active
pinocytosis and potocytosis (active/passive)
active
receptor-mediated endocytosis (active/passive)
active
