46 Key Terms
- active transport
- method of transporting material that requires energy
- amphiphilic
- molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments
- antiporter
- transporter that carries two ions or small molecules in different directions
- aquaporin
- channel protein that allows water through the membrane at a very high rate
- carrier protein
- membrane protein that moves a substance across the plasma membrane by changing its own shape
- caveolin
- protein that coats the plasma membrane’s cytoplasmic side and participates in the liquid uptake process by potocytosis
- channel protein
- membrane protein that allows a substance to pass through its hollow core across the plasma membrane
- clathrin
- protein that coats the plasma membrane’s inward-facing surface and assists in forming specialized structures, like coated pits, for phagocytosis
- concentration gradient
- area of high concentration adjacent to an area of low concentration
- diffusion
- passive transport process of low-molecular weight material according to its concentration gradient
- electrochemical gradient
- a combined electrical and chemical force that produces a gradient
- electrogenic pump
- pump that creates a charge imbalance
- endocytosis
- type of active transport that moves substances, including fluids and particles, into a cell
- exocytosis
- process of passing bulk material out of a cell
- facilitated transport
- process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins
- fluid mosaic model
- describes the plasma membrane’s structure as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to proteins or lipids, respectively), resulting in a fluid character (fluidity)
- glycolipid
- combination of carbohydrates and lipids
- glycoprotein
- combination of carbohydrates and proteins
- hydrophilic
- molecule with the ability to bond with water; “water-loving”
- hydrophobic
- molecule that does not have the ability to bond with water; “water-hating”
- hypertonic
- situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell, resulting in water moving out of the cell
- hypotonic
- situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell, resulting in water moving into the cell
- integral protein
- protein integrated into the membrane structure that interacts extensively with the membrane lipids’ hydrocarbon chains and often spans the membrane
- isotonic
- situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell, resulting in no net water movement into or out of the cell
- osmolarity
- total amount of solutes dissolved in a specific amount of solution
- osmosis
- transport of water through a semipermeable membrane according to the