Chapter 5 Vocab Flashcards
the selectively permeable surface membrane that encloses the cell contents and through which all materials entering or leaving the cell must pass
Plasma Membrane
a molecule containing both hydrophobic and hydrophilic regions
Amphipathic Molecules
the currently accepted model of the plasma membrane and other cell membranes, in which protein molecules “float” in a fluid phospholipid bilayer
Fluid Mosaic Model
a protein that is tightly associated with the lipid bilayer of a biological membrane; a transmembrane integral protein spans the bilayer
Integral Membrane Proteins
an integral membrane protein that spans the lipid bilayer
Transmembrane Proteins
a protein associated with one of the surfaces of a biological membrane
Peripheral Membrane Proteins
a protein with covalently attached carbohydrates
Glycoproteins
a membrane that allows some substances to cross it more easily than others. Biological membranes are generally permeable to water but restrict the passage of many solutes
Selectively Permeable Membranes
any form of transport across a membrane that uses a membrane-bound transport protein with a binding site for a specific substance; includes both facilitated diffusion and carrier-mediated active transport
Carrier-Mediated Transport
ATP-binding cassette transporters; use ATP energy to transport certain ions, sugars, and polypeptides across cell membranes
ABC Transporters
one of a family of transport proteins located in the plasma membrane that facilitate the rapid movement of water molecules into or out of cells
Aquaporins
the net movement of particles (atoms, molecules, or ions) from a region of higher concentration to a region of lower concentration
Diffusion
a difference in the concentration of a substance from one point to another, as for example, across a cell membrane
Concentration Gradient
the condition of a chemical reaction when the rate of change in one direction is exactly the same as the rate of change in the opposite direction, and the difference in free energy between reactants and products is zero
Dynamic Equilibrium
small, non-polar, solute molecules move directly through the membrane down the concentration gradient
Simple Diffusion
a term applied to solutions that have identical concentrations of solute molecules and hence the same osmotic pressure
Isotonic
the net movement of water by diffusion through a selectively permeable membrane from a higher concentration of water to a lower concentration of water
Osmosis
the pressure that must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water from the side containing pure water
Osmotic Pressure
a term referring to a solution having an osmotic pressure greater than that of the solution with which it is compared
Hypertonic
a term of referring to a solution having an osmotic pressure less than that of the solution with which it is compared
Hypotonic
hydrostatic pressure that develops within a walled cell and presses outward against the plasma membrane
Turgor Pressure
the shrinkage of cytoplasm and the pulling away of the plasma membrane from the cell wall when a plant cell loses water, usually in a hypertonic environment
Plasmolysis
the passive transport of ions or molecules by a specific carrier protein in a membrane
Facilitated Diffusion
transport of a substance across a membrane that does not rely on the potential energy of a concentration gradient for the substance being transported and therefore requires an additional energy source
Active Transport
ATP-binding cassette transporter in the plasma membrane of all animal cells; uses ATP energy to transport Na+ out of the cell and K+ into the cell
Sodium-Potassium Pump
a difference in electric charge between the 2 sides of a membrane
Membrane Potential
a difference in charge and chemical concentration existing between 2 regions
Electrochemical Gradient
membrane carrier protein that transports one type of substance in one direction
Uniporters
membrane carrier protein that transports 2 types of substances in one direction
Symporters
membrane carrier protein that transports 2 types of substances in opposite directions
Antiporters
the active transport of a substance from a region of low concentration to a region of high concentration by coupling its transport to the transport of a substance down its concentration gradient
Cotransport
the active transport of materials out of the cell by fusion of cytoplasmic vesicles with the plasma membrane
Exocytosis
“cell eating”; a type of endocytosis by which certain cells engulf food particles, microorganisms, foreign matter, or other cells
Phagocytosis
“cell drinking”; a type of endocytosis by which cells engulf and absorb droplets of liquids
Pinocytosis
a type of endocytosis in which extracellular molecules become bound to specific receptors on the cell surface and then enter the cytoplasm enclosed in vesicles
Receptor-Mediated Endocytosis
a molecule that binds to a specific site in a receptor or other protein
Ligand
button-like plaques, present on 2 opposing cell surfaces, that hold the cells together by means of protein filaments that span the intercellular space
Desmosomes
transmembrane proteins that are components of adhering junctions between animal cells
Caherins
specialized structures that form between some animal cells, producing a tight seal that prevents materials from passing through the spaces between the cell
Tight Junctions
structure consisting of specialized regions of the plasma membrane of 2 adjacent cells; contains numerous pores that allow the passage of certain small molecules and ions between them
Gap Junction
cytoplasmic channels connecting adjacent plant cells and allowing for the movement of molecules and ions between cells
Plasmodesmata
