Chapter 5 (Membrane)
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39 terms
Terms | Definitions |
|---|---|
 active transport | use of a plasma membrane carrier protein to move a molecule or ion from a region of lower concentration to one of higher concentration; it opposes equilibrium and requires energy. |
| adhesion junction | junction between cells in which adjacent plasma membranes do not touch but are held together by intercellular filaments attacked to buttonlike thickenings. |
| aquaporin | channel protein through which water can diffuse across a membrane |
| bulk transport | movement of elements in an organism in large amount |
| carrier protein | protein that combines with a molecule or ion to transport it across the plasma membrane |
| cell recognition protein | glycoprotein that helps the body recognize when it is being invaded by pathogens so that an immune response can occur |
| cell wall | structure that surrounds a plant, protistan, fungal, or bacterial cell and maintains the cell's shape and rigidity. |
| channel protein | protein that forms a channel to allow a particular molecule or ion to cross the plasma membrane |
| cholesterol | a steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids. |
| concentration gradient | difference in the number of molecules or ions of any one substance between two adjoining regions |
| crenation | in animal cell, shriveling of the cell due to water leaving the cell when the environment is hypertonic |
| desmosome | intercellular junction that connects cytoskeletons of adjacent cells; fastens cells together as strong sheets |
| differentially permeable | ability of membranes to regulate the passage of substances into and out of the cell; allowing some to pass through and preventing the passage of others |
| diffusion | net movement of like ions or molecules from a region where they are most concentrated to an adjoining region where they are less concentrated; they move down their concentration gradient and use no energy |
| endocytosis | cell uptake of substances by forming vesicles from patches of plasma membrane. three modes: receptor-mediated endocytosis, phagocytosis, and pinocytosis (cell drinking) |
| enzymatic protein | protein that catalyzes a specific reaction |
| exocytosis | process in which an intracellular vesicle fuses with the plasma membrane so that the vesicle's contents are released outside the cell |
| extracellular matrix | nonliving substance in which animal cells are imbeded; is composed of protein and polysaccharides |
| facilitated transport | passive transfer of molecules and ions, bound to specific carrier proteins, across a biological membrane down their concentration gradients. moves from high to low concentration. |
| fluid-mosaic model | model for the plasma membrane based on the changing location and pattern of protein molecules in a fluid phospholipid bilayer |
| gap junction | junction between cells formed by the joining of two adjacent plasma membranes; it lends strength and allows ions, sugars, and small molecules to pass through cells |
| glycolipid | lipid in plasma membranes covalently bonded to a carbohydrate |
| glycoprotein | protein in plasma membranes that bears a carbohydrate chain |
| hypertonic solution | higher solute concentration (less water) than the cytoplasm of a cell; causes cell to lose water by osmosis |
| hyopotonic solution | lower solute (more water) concentration than the cytoplasm of a cell; causes cell to gain water by osmosis |
| isotonic solution | solution that is equal in solute concentration to that of the cytoplasm of a cell; causes cell to neither lose nor gain water by osmosis |
| osmosis | diffusion of water through a differentially permeable membrane |
| osmotic pressure | measure of the tendency of water to move across a differentially permeable membrane; visible as an increase in liquid on the side of the membrane with higher solute concentration |
| phagocytosis | process by which amoeboid-type cells engulf large substances, forming an intracellular vacuole |
| pinocytosis | process by which vesicle formation brings macromolecules into the cell. |
| plasmodesmata | in plants, cytoplasmic strands that extend through pores in the cell wall and connect the cytoplasm of two adjacent cells substances can travel between cells this way http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Plasmodesmata.gif |
| plasmolysis | contraction of the cell contents due to the loss of water |
| receptor-mediated endocytosis | selective uptake of molecules into a cell by vacuole formation after they bind to specific receptor proteins in the plasma membrane |
| receptor protein | protein located in the plasma membrane or within the cell; binds to a substance that alters some metabolic aspect of the cell |
| sodium-potassium pump | cotransporter that, when energized, actively transports sodium out of a cell and helps potassium passively diffuse into it at the same time |
| tight junction | junction between cells when adjacent plasma membrane proteins join to form an impermeable barrier |
| tonicity | the ability of a solution to cause a cell within it to gain or lose water |
| turgor pressure | pressure of the cell's contents against the cell wall; in plant cells, determined by the water content of the vacuole and provides internal support |
| junction protein | protein that assists cell-to-cell communication at the plasma membrane |
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