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Definition
| each membrane consists of a mosaic, or "patchwork", of different proteins that constantly shift and flow within a visous (thick, sticky) fluid formed by a double layer of phospholipids. |
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| a double layer of phospholipids that forms the basis of all cellular membranes. The phospholipid heads face the water of extacellular fluid or the cytoplasm; the tails are buried in the middle of the bilayer |
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| a biological catalyst, usually a protein, that speeds up the rate of specific biological reactions |
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| a protein that regulates the movement of water-soluble molecules through the plasma membranes |
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| 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 |
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| a substance that can be dissolved (dispersed into individual atoms, molecules, or ions) |
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| a fluid (usually a liquid) capable of dissolving the solute |
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| a physical difference in properties such as temperature, pressure, electrical charge, or concentration of a particular substance in a fluid between two adjoining regions of space (requires energy) |
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| the difference in concentration of a substance between two parts of a fluid or across a barrier such as a membrane |
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| the quality of a membrane that allows certain molecules or ions to move through it more readily than others |
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| the movement of materials across a membrane down a gradient of concentration, pressure, or electrical charge without using cellular energy |
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| a diffusion of water, dissolved gases, or lipid-soluable molecules through the phospholipid bilayer of a cellular membrane |
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| the diffusion of molecules across a membrane, assisted by protein pores or carriers embedded in the membrane |
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| a channel protein in the plasma membrane of the cell that is selectively permeable to water |
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| the diffusion of water across a differentially permeabe membrane, normally down a concentration gradient of free water molecules. Water moves into the solution that has a lower concentration of free water from a solution with a higher concentration of free water |
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Definition
referring to a solution that has the same concentration of dissolved particles as has the cytoplasm of a cell
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| referring to a solution that has a higher concentration of dissolved particles than has the cytoplasm of a cell |
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| referring to a solution that has a lower concentration of dissolved particles than has the cytoplasm of a cell |
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| the movement of materials across a membrane through the use of cellular energy, normally against a concentration gradient |
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| 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 |
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| 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 of the cell |
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Definition
| the nonselective movement of extracellular fluid, enclosed within a vesicle formed from the plasma membrane, into the cell |
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Term
| Receptor-mediated endocytosis |
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Definition
| the selective uptake of molecules from the extracellular fluid by binding to a receptor located at a coated pit on the plasma membrane and pinching off the coated pit into a vesicle that moves into the cytoplasm |
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| the type of endocytosis in which extensions of a plasma membrane engulf extracellular particles, enclose them in a membrane-bound sac, and transport them into the interior of the cell |
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| the complete series of chemical reactions in which the energy of light is used to syntheize high-energy organic molecules, usually carbohydrates, from low-energy inorganic molecules, usually carbon dioxide and water |
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| an adjustable opening in the epidermis of a leaf or young stem, surrounded by a pair of guard cells, that regulates the diffusion of carbon dioxide and water into and out of the leaf or stem |
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| the semifluid material inside chloroplasts in which the thylakoids are located; the site of the reactions of the calvin cycle |
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| a disk-shaped membranous sac found in chloroplasts, the membranes of which contain the photsystems, electron trasnport chains, and ATP-synthesizing enzymes used in the light reactions of photosyntesis |
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Definition
| in photosyntesis, the cyclic series of reactions whereby caron from carbon dioxide is fixed as phophoglyceric acid, the simple sugar glyeraldehyde-3-phosphate is generated, and the carbon-capture molecule. RuBP, is regenerated |
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| the smallest unit of light energy |
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| a pigment found in chloroplasts that captures light energy during photosynthesis; absorbs violet, blue, and red light but reflects green light |
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Definition
| a red, orange, or yellow pigment, found in chloroplasts, that serves as an accessory light-gathering pigment in thylakoid photosynthesis |
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Definition
| in thylakoid membranes, a cluster of chlorophyll, accessory pigment molecules, proteins, and other molecules that collectively capture light energy, transfer some of the energy to electrons and transfer the energetic electrons to an adjacent electron transport chain |
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Term
| Electron Trasport Chain (ETC) |
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Definition
| a series of elecyron carrier molecules, found in the thylakoid membranes of chloroplasts and the inner membrane of mitochondria, that extract energy from electrons and generate ATP or other energetic molecules |
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Definition
| two chlorophyll molecules and a primary electon acceptor complexed with proteins and located near the center of each photsystem within the thylakoid membrane. Light energy is passed to one of the chlorophylls, which donates an energixed electron to the primary electron acceptor, which then passes the electron to an adjacent electron transport chain |
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Definition
| a process of ATP generation in chloroplasts and mitochondria. The movement of electrons down an electron transport system is used to pump hydrogen ions across a membrane, thereby building up a concentration gradient of hydrogen ions; the hydrogen ions diffuse back across the membrane through the pores of ATP-syntesizing enzymes; the energy of their movement down their concentration gradient drives ATP synthesis |
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Definition
| the process by which carbon derived from carbon dioxide is captured in organic molecules during photosynthesis |
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Definition
| in photosyntesis, the cyclic series of reactions whereby carbon from carbon dioxide is fixed as phosphpglyceric acid, the simple sugar glyceraldehyde-3-phosphate is generated, and the carbon-capture molecule, RuBP, is regenerated |
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Definition
| a series of reactions in plants in which O2 replaces CO2 during the Calvin Cylce, preventing caron fixation; this wasteful process dominates when C3 plants are forced to close their stomata to prevent water loss |
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| a plant that relies on the C3 pathway to fix carbon |
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| a plant that relies on the C4 pathway to fix carbon |
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| the series of reactions in certain plants that fixes Carbon Dioxide into a four-carbon moluculem which is later broken down for use in the Calvin cycle of photosyntesis. This reduces wasteful photorespiration in hot, dry environments |
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Term
| Adenosine Triphosphate (ATP) |
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Definition
| a molecule composed of te sugar ribose, the base Adenine, and three phosphate groups; the major energy carrier in cells. The last two phosphate groups are attached by "high-energy" bonds |
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Definition
| reactions, carried out in the cytoplasm, that break down glucose into two molecules of pyruvic acid, producing two ATP molecules; does not require oxygen but can proceed when oxygen is present |
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| the oxygen-requiring reactions, occuring in mitochondria , that break down the end products of glycolysis into carbon dioxide and water while capturing large amounts of energy as ATP |
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Definition
| anaerobic reactions that convert the pyruvic acid produced by glycolysis into lactic acid or alcohol and CO2 using hydrogen ions and electrons from NADH; the primary function of fermentation is to regenerate NAD+ so that glycolysis can continue under anaerobic conditions |
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Term
| Adenosine Diphosphate (ADP) |
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Definition
| a molecule composed of the sugar ribose, the base adenine, and tow phosphate groups; a component of ATP |
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Term
| Nicotinamide adenine dinucleotide (NAD+ or NADH) |
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Definition
| an electron carrier molecule produced in the cytoplasmic fluid by glycolysis and in the mitochondrial matrix by the Krebs Cycle; subsequently donates electrons to the electron transport chain |
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Definition
| a fluid-filled space between the inner and outer membranes of a mitochondria |
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Definition
| a cyclic series of reactions, occuring in the matrix of mitochondria, in which the acetyl groups from the pyruvic acids produced by glycolysis are broken down to CO2 , accompanied by the formation of ATP and electron carriers; also called the citric acid cycle |
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Term
| Flavin adenine dinucleotide (FAD or FADH2) |
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Definition
| an electron carrier molecule produced in the mitochondrial matrix by the Krebs cycle; subsequently donates electrons to the electron transport chain |
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Definition
| anaerobic reactions that convert the pyruvic acid produced by glycolysis into lactic acid, using hydrogen ions and electrons from NADH; the primary function of lactic acid fermentation is to regenerate NAD+ so that glycolysis can continue under anaerobic conditions |
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Definition
| defines the amount of solute in a given amount of solvent |
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Definition
| 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 |
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Definition
| in a chemical reaction, the energy needed to force the electron shells of reactants together, prior to the formation of products |
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Definition
| the region of an enzyme molecule that binds substrates and performs the catalytic function of the enzyme |
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Definition
| the process by which enzyme action is enhanced or inhibited by small organic molecules that act as regulators by binding to the enzyme at a regulatory site distinct from the active site, and altering the shape and/or function of the active site |
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Definition
| a substance that speeds up a chemical reaction without itself being permanently changed in the process; a catalyst lowers the activation energy of a reaction |
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Definition
| the process that forms and breaks chemical bonds that hold atoms together in molecules |
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Definition
| the process by which two or more molecules that are somewhat similar in structure compete for the active site of an enzyme |
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Definition
| a pair of reactions, one exergonic and one endergonic, that are linked together such that the energy produced by the exergonic reaction provides the energy needed to drive the endergonic reaction |
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| a molecule that can reversibly gain or lose electrons. generally accept high-energy electrons produced during an exergonic reaction and donate the electrons to acceptor molecules that use the energy to drive endergonic reactions |
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| pertaining to a chemical reaction that requires an input of energy to proceeed; an "uphill" reaction |
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| pertaining to a chemical reaction that releases energy (either as hear or in the form of increased entropy); a "downhill" reaction |
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| in enzyme-mediated chemical reactions, the condition in which the product of a reaction inhibits one or more of the enzymes involved in synthesizing the product |
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| the energy of movement; includes light, heat, mechanical movement, and electricity |
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Definition
| a sequence of chemical reactions within a cell, in which the products of one reaction are the reactants for the next reaction |
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| the sum of all chemical reactions that occur within a single cell or within all the cells of a multicellular organism |
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Definition
| "stored" energy; normally chemical energy or energy of position within a gravitational field |
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Definition
| an atom or molecule that is formed from reactants in a chemical reaction |
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Definition
| an atom or molecule that is used up in a chemical reaction in all parts of an area |
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| the atoms or molecules tat are the reactants for an enzyme-catalyzed chemical reaction |
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| the fluid contained within the inner membrane of the mitochondrian |
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| Pyruvate is the end product of glycolysis |
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