3.1. Cell Membrane Flashcards
Three types of integrated membrane proteins…
- Integral: have hydrophobic amino acids that can either fully or partially penetrate the cell membrane.
- Peripheral: don’t have any hydrophobic components and don’t penetrate the membrane, only tag onto other proteins.
- Transmembrane: have specific orientations, showing different faces on the two sides of the membrane.
Two types of binding…
Homotypic: molecules of the same protein occur on the surfaces of two cells of the same type and adhere to each other.
Heterotypic: binding between two different, but complementary, proteins.
Three types of cell junctions…
Desmosomes: hold adjacent cells together. Dense plaques attach both to cytoplasmic fibres and to membrane cell adhesion proteins, which bind to proteins of adjacent cells.
Gap junctions: connections that facilitate communication between cells. Made up of specialised proteins called connexons. These also snap together to create a pore.
Tight junctions: specialised structures at the plasma membrane that link adjacent epithelial cells that aim to restrict migration of membrane proteins and phospholipids and prevent substances moving through the intercellular space.
_____tonic…
Hypertonic: a solution that has a higher solute concentration than the other solution with which it is being compared.
Isotonic: a solution that has an equal solute concentration than the other solution with which it is being compared.
Hypotonic: a solution that has a lower solute concentration than the other solution with which it is being compared.
Three types of active transport mechanisms…
Uniport: moves a single substance in one direction.
Symport: moves two substances in the same direction.
Antiport: moves two substances in opposite directions, one into the cell and one out of the cell.
Endocytosis…
Phagocytosis: the engulfing of entire cells by phagocytes to defend the body. Common among unicellular protists.
Pinocytosis: ‘cellular drinking’. Dissolved substances and fluids are brought into the cell. It can also involve forming vesicles, but they are much smaller than usual.
Receptor-mediated endocytosis: highly specific. Receptor proteins are exposed on the outside of the cell in regions called coated pins.
Exocytosis…
A process by which materials packed into vesicles are secreted from the cell.
Vesicle membranes fuse with the plasma membrane and release their contents into the environment.
