EX3 Terms - 1 Chapter 5 Key Terms Active Transport: the...

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1 Chapter 5 Key Terms Active Transport: the movement of materials across a membrane through the use of cellular energy, normally against a concentration gradient. Aquaporin: specialized water channels. “water pores” that allow water to cross membranes by facilitated diffusion, which is faster than simple diffusion. Attachment Protein: anchor the cell membrane in various ways. Some bind the plasma membrane to network of protein filaments within the cytoplasm called the cytoskeleton. Carrier Protein: a membrane protein that facilitates the diffusion of specific substances across the membrane. The molecule to be transported binds to the outer surface of the carrier protein; the protein then changes shape; allowing the molecule to move across the membrane through the protein. Channel Protein: a membrane protein that forms a channel or pore completely through the membrane and that is usually permeable to one or to a few water-soluble molecules, especially ions. Cleavage: the early cell divisions of embryos, in which little or no growth occurs between divisions; reduces the cell size and distributes gene-regulating substances to the newly formed cell. Concentration: the number of particles of a dissolved substance in a given unit of volume. Concentration Gradient: the difference in concentration of a substance between two parts of a fluid or across a barrier such as a membrane. Desmosome: a strong cell-to-cell junction that attaches adjacent cells to one another. Diffusion: the net movement of particles from a region of high concentration of that particle to a region of low concentration, driven by the concentration gradient; may occur entirely within a fluid or across a barrier such as a membrane. Endocytosis: the process in which the plasma membrane engulfs extracellular material, forming membrane –bound sacs that enter the cytoplasm and thereby move material into the cell. Exocytosis: the process in which intracellular material is enclosed within a membrane-bound sac that moves to the plasma membrane and fuses with it, releasing the material outside the cell. Facilitated Diffusion: the diffusion of molecules across a membrane, assisted by protein pores or carriers embedded in the membrane. Fluid: a liquid or gas
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2 Fluid Mosaic Model: a model of membrane structure; according to this model, membranes are composed of a double layer of phospholipids in which various proteins are embedded. The phospholipid bilayer is a somewhat fluid matrix that allows the movement or proteins within it. Gap Junction: a type of cell-to-cell junction in animals in which channels connect the cytoplasm of adjacent cells. Glysoprotein: a protein to which a carbohydrate is attracted. Gradient: a difference in concentration pressure, or electrical charge between two regions.
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EX3 Terms - 1 Chapter 5 Key Terms Active Transport: the...

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