Substances move across membranes by simple diffusion, facilitated diffusion, osmosis and active transport.
Passive Transport
Simple Diffusion: Movement of particles from a region of high concentration to a region of low concentration
Facilitated Diffusion: Movement of particles from a region of high concentration to low concentration through carrier proteins (either channel proteins or proteins that change their shape allowing some substances to pass)
Facilitated Diffusion: Movement of particles from a region of high concentration to low concentration through carrier proteins (either channel proteins or proteins that change their shape allowing some substances to pass)
Osmosis: Movement of water molecules from a region of high water concentration to low water concentration through aquaporins (carrier proteins used specifically for water)
Active Transport
•Uses energy, in the form of ATP, to move molecules against a concentration gradient, using membrane protein pumps
One substance will act as an opener, it will be expelled (pumped out) using ATP, changing the form of the protein (so that it's aperture is on the outside of membrane) and the substance that wants to get inside will enter through the protein's aperture, and after the protein goes back to its original position, the aperture will be facing the inside of the cell, which creates the entrance for the new substance
Example: Sodium Potassium pump. (the sodium is the substance expelled and the potassium molecules enter)
•Uses energy, in the form of ATP, to move molecules against a concentration gradient, using membrane protein pumps
One substance will act as an opener, it will be expelled (pumped out) using ATP, changing the form of the protein (so that it's aperture is on the outside of membrane) and the substance that wants to get inside will enter through the protein's aperture, and after the protein goes back to its original position, the aperture will be facing the inside of the cell, which creates the entrance for the new substance
Example: Sodium Potassium pump. (the sodium is the substance expelled and the potassium molecules enter)
For Large Particles..
Exocytosis: The Export of macromolecules from the cell (through secretion) through secretory vesicles. The vesicle unites with the membrane and the substance is released, and the vesicle becomes part of the membrane
Endocytosis: The import of macromolecules from the cell by pinching a part of the membrane until it breaks off inside the cell with the substance inside (infolding of the membrane).
Vesicle: a small organelle within a cell, consisting of fluid enclosed by a lipid bilayer membrane
Materials that usually go through endo/exocytosis are nutrients and waste material
Exocytosis: The Export of macromolecules from the cell (through secretion) through secretory vesicles. The vesicle unites with the membrane and the substance is released, and the vesicle becomes part of the membrane
Endocytosis: The import of macromolecules from the cell by pinching a part of the membrane until it breaks off inside the cell with the substance inside (infolding of the membrane).
Vesicle: a small organelle within a cell, consisting of fluid enclosed by a lipid bilayer membrane
Materials that usually go through endo/exocytosis are nutrients and waste material