active transport-lecture 11

active transport defintion

cell membrane moves against concentration gradient

primary active transport

energy derived from atp or another high energy phosphate compound

secondary active transport

derived from ionic concentration differences

endocytosis/exocytosis

energy from ATP

primary sodium-potassium pump

1. transports 3 Na+ ions out and 2 K+ ions in

2. creates electrical potential across the membrane making it electronegative

primary active transport of calcium ions

Ca2+ ATPase maintains a low cytosolic Ca2+ concentration

what are the two calcium pumps?

PMCA and SERCA

where is PMCA?

in the plasma membrane

where is SERCA?

in the membrane of the sarcoplasmic reticulum of muscle cells

primary active transport of hydrogen ions

proton pumps that use the energy from ATP hydrolysis to move H+ ions against their electrochemical gradient across a membrane

secondary active transport

1. does not use ATP directly

2. uses energy of the sodium gradient to move other substances against their concentration gradients

3. uses co-transport and counter-transport

symporters

transports substances in the same direction as a “driver” ion like Na+

secondary active transport- sodium and glucose

glucose is transported against the concentration gradient by CO-TRANSPORT

sodium-glucose co transporters are important in which cells?

renal and intestinal epithelial cells

secondary- sodium and amino acids

uses the electrochemical gradient of sodium ions to drive the simultaneous import of amino acids and glucose

antiporters

counter transports substances in opposite direction of “driver” ion like Na+

secondary counter transport of calcium ions

sodium calcium ions occurs through all or almost all cell membranes

secondary counter transport of hydrogen ions

transports extremely large numbers of hydrogen ions making it essential to hydrogen ion control in body fluids

active transport through cellular sheets mechanisms

1. active transport through cell membrane on one side of the transporting cells in the sheet

2. simple or facilitated diffusion through the membrane on the opposite side of the cell

bulk transport endocytosis

phagocytosis, pinocytosis, and receptor-mediated all require vesicles and energy

bulk transport exocytosis

requires vesicles and energy