Active And passive transport
Active transport
the movement of ions or molecules across a cell membrane into a region of higher concentration, assisted by enzymes and requiring energy.Active transport usually happens across the cell membrane.active transport uses cellular energy to move them against a gradient, polar repulsion, or other resistance. Active transport is usually associated with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acids.Active transport usually happens across the cell membrane. There are thousands of proteins embedded in the cell's lipid bilayer. Those proteins do much of the work in active transport. They are positioned to cross the membrane so one part is on the inside of the cell and one part is on the outside. Only when they cross the bilayer are they able to move molecules and ions in and out of the cell. The membrane proteins are very specific. One protein that moves glucose will not move calcium (Ca) ions. There are hundreds of types of these membrane proteins in the many cells of your body.Many times, proteins have to work against a concentration gradient. That term means they are pumping something (usually ions) from areas of lower to higher concentration. This happens a lot in neurons. The membrane proteins are constantly pumping ions in and out to get the membrane of the neuron ready to transmit electrical impulses.
passive transport
PASSIVE TRANSPORT IS A MOVEMENT OF BIOCHEMICALS AND OTHER ATOMIC OR MOLECULAR SUBSTANCES ACROSS CELL MEMBRANES WITHOUT NEED OF ENERGY INPUT. UNLIKE ACTIVE TRANSPORT, IT DOES NOT REQUIRE AN INPUT OF CELLULAR ENERGY BECAUSE IT IS INSTEAD DRIVEN BY THE TENDENCY OF THE SYSTEM TO GROW IN ENTROPY. THE RATE OF PASSIVE TRANSPORT DEPENDS ON THE PERMEABILITY OF THE CELL MEMBRANE, WHICH, IN TURN, DEPENDS ON THE ORGANIZATION AND CHARACTERISTICS OF THE MEMBRANE LIPIDS AND PROTEINS. THE FOUR MAIN KINDS OF PASSIVE TRANSPORT ARE SIMPLE DIFFUSION, FACILITATED DIFFUSION.THERE ARE THREE FORMS OF PASSIVE TRANSPORTS. DIFFUSION, OSMOSIS, AND FACILITATED DIFFUSION. DIFFUSION IS THE NET MOVEMENT OF IONS OR MOLECULES FROM AN AREA OF HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION UNTIL EQUILIBRIUM IS REACHED. TEMPERATURE AND PRESSURE – THE RATE OF DIFFUSION INCREASES WITH INCREASED TEMPERATURE AND PRESSURE. OSMOSIS ISTHE MOVEMENT OF WATER FROM AN AREA OF HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION, ACROSS A SEMI-PERMEABLE MEMBRANE UNTIL EQUILIBRIUM IS REACHED. FACILITATED DIFFUSION
FACILITATED DIFFUSION IS THE PROCESS OF DIFFUSION THAT IS MEDIATED BY A MEMBRANE PROTEIN.FACILITATED DIFFUSION IS THE PROCESS OF SPONTANEOUS PASSIVE TRANSPORT OF MOLECULES OR IONS ACROSS A CELL'S MEMBRANE VIA SPECIFIC TRANSMEMBRANE INTEGRAL PROTEINS. energy is not required.
FACILITATED DIFFUSION IS THE PROCESS OF DIFFUSION THAT IS MEDIATED BY A MEMBRANE PROTEIN.FACILITATED DIFFUSION IS THE PROCESS OF SPONTANEOUS PASSIVE TRANSPORT OF MOLECULES OR IONS ACROSS A CELL'S MEMBRANE VIA SPECIFIC TRANSMEMBRANE INTEGRAL PROTEINS. energy is not required.