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| Any structure within a cell that carries out one of its metabolic roles, such as mitochondria, centrioles, endoplasmic reticulum, and the nucleus; an intracellular structure other than the cytoskeleton and inclusions. |
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| The current theory of the structure of the plasma membrane, depicting it as a bilayer of phospholipids with embedded proteins, many of which are able to move about in the lipid film. |
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| A difference or change in any variable, such as pressure or chemical concentration, from one point in space to another; provides a basis for molecular movements such as gas exchange, osmosis and fascilitated diffusion. |
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| A simple squamous epithelium that lines the lumens of the blood vessels, heart, and lymphatic vessels. |
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| A protein that extends through a plasma membrane and contacts both the extracellular and intracellular fluid |
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| An outgrowth of the plasma membrane that increases the surface area of a cell and functions in absorption and some sensory processes; distinguished from cilia and flagella by its smaller size and lack of an axoneme |
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| A clear, featureless, gelatinous colloid in which the organelles and other internal structures of a cell are embedded. |
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| A cellular shape that is roughly like a cube or in which the height and width are about equal. |
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| The net diffusion of water through a selectively permeable membrane |
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| A fluid formed by filtration |
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| A chemical that is produced within a cell or that enters a cell in response to the biding of a messenger to a membrane receptor and that triggers a metabolic reaction in the cell. |
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| A protein in the plasma membrane that has a pore through it for the passage of materials between the cytoplasm and extracellular fluid. |
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| The physical force generated by a liquid such as blood or tissue fluid, as opposed to osmotic and atmospheric pressures. |
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| Selectively permeable membrane |
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| A membrane that allows some substances to pass through while excluding others; for example, the plasma membrane and dialysis membranes |
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| Transmission Electron Microscope |
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| A microscope that uses an electron beam in place of light to form high-resolution, two dimensional images of ultrathin slices of cells or tissues; capable of extremely high magnification |
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| The core of microtubules, usually in a "9 + 2" array, at the center of cilium or flagellum |
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| A carrier protein that moves two solutes simultaneously through a plasma membrane in the same direction, such as the sodium-dependent glucose transporter of the small intestine. |
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| Any membrane composed of a bilayer of phospholipids and embedded proteins. A single unit membrane comprises the plasma membrane and encloses many organelles of a cell, whereas double unit membranes enclose the nucleus and mitochondria. |
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| Any process in which a cell forms vesicles from its plasma membrane and takes in large particles, molecules, or droplets of extracellular fluid; for example, phagocytosis and pinocytosis. |
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| The uppermost surface of an epithelial cell, usually exposed to the lumen of an organ. |
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| The D-isomer of glucose; the only form of glucose with a normal role in physiology. |
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| A protein of the plasma membrane that is activated by a membrane receptor and, in turn, opens an ion channel or activates an intracellular physiological response; important in linking ligand-receptor binding to second messenger systems. |
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| An extensive system of interconnected cytoplasmic tubules or channels; classified as rough ER or smooth ER depending on the presence or absence of ribosomes on its membrane. |
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| Having a lower osmotic pressure than human cells or some other reference solution and tending to cause osmotic swelling and lysis of cells. |
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| The movement of a solute through a cellular membrane, against its concentration gradient, involving a carrier protein that expends ATP. |
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| A fluid-filled space or sac, such as the cisterna chyli of the lymphatic system and a cisterna of the endoplasmic reticulum or Golgi Complex |
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| A system of protein microfilaments, intermediate filaments, and microtubules in a cell, serving in physical support, cellular movement, and the routing of molecules and organelles to their destinations within the cell. |
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| A process in which hydrostatic pressure forces a fluid through a selectively permeable membrane |
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| The amount of pressure that would have to be applied to one side of a selectively permeable membrane to stop osmosis; proportional to the concentration of nonpermeating solutes on that side and therefore serving as an indicator of solute concentration |
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| An organelle specialized to synthesize ATP, enclosed in a double unit membrane with infoldings of the inner membrane called cristae |
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| A hairlike process, with an axoneme, projecting from the apical surface of an epithelial cell; usually motile and serving to propel matter across the surface of an epithelium but sometimes serving sensory roles. |
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| A channel protein in a plasma membrane that opens or closes when a ligand binds to it, enabling the ligand to determine when substances can enter or leave a cell. |
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| a cellular organelle containing DNA ad surrounded by a double unit membrane |
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| Any unit membrane enclosing a cell or organelle |
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| a protein in a cellular membrane that performs carrier-mediated transport. |
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| a Microscope that produces images within visable light. |
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| an intracellular cylinder composed of the protein tubulin, forming the axonemes of the cilia and flagella and part of the cytoskeleton |
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| A form of endycytosis in which a cell surrounds a foreign particle with pseudopods and engulfs it enclosing it in a cytoplasmic vesicle called a phagosome. |
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| A filamentous intracellular protein that provides cytoskeletal support and interacts with other proteins, especially myosis, to cause cellular movement; important in muscle contraction, ciliary and flagellar beating, and membrane actions such as phagocytosis, ameboid movement, and cytokinesis. |
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| An active transport carrier that moves two or more solutes in opposite directions through a cellular membrane; for example, the Na+ - K+ pump. |
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| Carrier-Mediated Transport |
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Definition
| A process of transporting materials through a cellular membrane that involves reversible binding to a membrane protein. |
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| An organelle composed of two short perpendicular cylinders of microtubules; origin of the mitotic spindle. |
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| A gradual change in chemical concentration from one point to another. |
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| A form of endycytosis in which the plasma membrane sinks inward and imbibes droplets of extracellular fluid or specific molecules concentrated from that fluid. |
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| A long, Motile, usually single hairlike extension of a cell; the tail of a sperm cell is the only functional flagellum in humans. |
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| A form of endocytosis in which the cell imbibes droplets of extracellular fluid without modifying its composition or concentration. |
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| Spindle-shaped; elongated, thick in the middle, and tapered at both ends, such as the shape of a smooth muscle cell or a muscle spindle. |
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| A motor protein involved in the beating of cilia and flagella and in the movement of molecules and organelles within cells, as in retrograde transport in a nerve fiber. |
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| Having a higher osmotic pressure than human cells or some other reference solution and tending to cause osmotic shrinkage of cells. |
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| A temporary cytoplasmic extension of a cell used for locomotion and phagocytosis |
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| Receptor-Mediated Pinocytosis |
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| A form of endocytosis in which certain molecules in the extracellular fluid bind to receptors in the plasma membrane, these receptors become gathered together, the membrane sinks inward at that point, and the molecules become incorporated into vesicles in the cytoplasm |
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| The contents of a cell between its plasma membrane and its nuclear envelope, consisting of cytosol, organelles, inclusions, and the cytoskeleton |
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| Movement of a cell by means of pseudopods, in a manner similar to that of an ameba; seen in leukocytes and some macrophages. |
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| An organelle composed of several parallel cisternae, somewhat like a stack of saucers, that modifies and packages newly synthesized proteins and synthesizes carbohydrates. |
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| A membrane-bounded vesicle pinched from the Golgi Complex, containing its chemical product; may be retained in the cell as a lysosome or become a secretory vesicle that releases the product by exocytosis. |
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| A protein Channel in a unit membrane that can open or close in response to chemical or electrical stimuli, thus controlling when substances are allowed to pass through the membrane. |
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| A fine, Branching collagen fiber coated with glycoprotein, found in the stroma of lymphatic organs and some other tissues and organs. |
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| Secondary-Active Transport |
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Definition
| A mechanism in which solutes are moved through a plasma membrane by a carrier that does not itself use ATP but depends on a concentration gradient established by an active transport pump elsewhere in the cell. Also called cotrasport. |
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| A chemical that binds protons from solution; a proton acceptor |
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| The fluid contained in the cells; one of the major fluid compartments |
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| The movement of particles or fluid droplets through the plasma membrane by the process of endocytosis or exocytosis. |
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| Any visible object in the cytoplasm of a cell other than an organelle or cytoskeletal element; usually a foreign body or a stored cell product, such as a virus, dust particle, lipid droplet, glycogen granule, or pigment. |
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| The process of transporting a chemical through a cellular membrane, down its concentration gradient, with the aid of a membrane carrier that does not consume ATP; enable substances to diffuse through the membrane that would do so poorly, or not at all, without a carrier |
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