| A | B |
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| Energy | Energy is the capacity to perform work. That is, to move matter in a direction it would not move if left alone. Energy makes change possible. |
| Kinetic Energy | Energy that is actually doing work, such as pedaling a bicycle. A mass of matter that is moving performs work by transfering its motion to other matter. |
| Heat | Energy associated with the movement of molecules in a body of metter. Light is another form of Kinetic Energy. |
| Potential Energy | Capacity to perform work that matter possesses as a reduly of its location or arrangement. A cyclist motionless at the top of a hill and water behind a dam both have potential energy due to their altitude. |
| Chemical Energy | The potential energy of molecule, the most important type of energy for living orgainisms. |
| Thermodynamics | The study of energy transformations that occur in a collection of matter. In discussing energy transformations, we call the collection of matter nder study the system and the rest of the univers the surroundings. |
| First Law of Thermodynamics | Also known as the law of energy conservation, the total amount of energy in the universe is constant. Energy can be transferred and transformed, but it cannot be created or destroyed. An electrical company does not make energy; it merely converts it to a form that is convenient to use. |
| Second Law of Thermodynamics | States that energy conversions reduce the order of the universe. Energy Changes, such as the conversion of chmical energy to kinetic energy, are accompanied by an increase in disorder or randomness. |
| Entropy | The amount of disorder in a system. Heat, which is a randome moleculat motion is one form of disorder. |
| Endergonic Reactions | Requires a net input of energy. They yield products that are rich in potential energy. Energy is absorbed fromt eh surroundings as the reaction occures, so that the products of an endergonic reaction store more energy that the reactants. |
| Exergonic Reactions | A chemical reaction that releases energy. An exergonic reaction begins with reactants whose covalent bonds contain more energy than those in the products. |
| Cellular Respiration | The energy releasing chemical breakdown of glucose molecules and the storage of the energy in a form that the cell can use to perform work. Burninig and Cellular Respiration are alike in being exergonic |
| Cellular Motabolism | The sum of total endergonic and exergonic reactions. |
| Energy coupling | Using energy released from exergonic reactions to drive essential endergonic reactions--is a crucial ability of all cells. ATP is the key energy coupling. |
| Phosphorylation | The transfer of a phosphate group to a molecule. Most cellular work depends on ATP energizing other molecules by phosphorylating them. |
| Energy of Activation | An energy barrier that is required to start a reaction. The reactants muct absorb energy to start a reaction. |
| Enzyme | A protien molecule that serves as a biological catalyst, increasing the rate of a reactions without itself being changed into a different molecule. An enzyme does not add enrgy to a cellular reaction, it speeds up a reaction by the lowering the Eneryg of Activation. |
| Substrate | A substanse that an enzyme acts on-- a reactant in a chemical reaction. Each enzyme recognizes only its specific substrate or substrates of the reaction in catalyzes. |
| Active site | The Small part of an enzyme that binds to a substrate. It is typically a small pocket or grooveon the surface of the enzyme. |
| Cofactors | Many enzymes will not work unless they are acoompanied by nonprotein helpers called cofactors. May be inorganic substances. |
| Coenzyme | If a cofactor is an organic molecule, it is called a coenzyme. Most coenzymes are compounds made from vitamins or are vitamins themselves. |
| Competitive inhibitor | Resembles the enzymes normal substrate and competes with the substrate for the active site on the enzyme. The competitive inhibitor blocks the substrate form entering and thereby prevents the enzyme from acting. |
| Noncompetitive inhinbitor | Does not enter the active site, but it binds to the enzyme somewhere outside the active site and changes the shape of teh enzyme so that the active site no longer fits the substrate. |
| Negative feedback | When a metabolic reaction is blocked by its produts. It is one of the most importnat mechanisms that regulate metabolism. |
| Selective Permeability | Allows some substances to cross more easily than others and blocks the passage of some substances altogether. Example is the plasma membrane. |
| Fluid mosiac | The surface of a membrane is made of small fragments. Individual pieces and protiens can drift laterally in the membrane. |
| Diffusion | The tendency for particles of any kind to spread out spontaneously from where they are more concentrated to where they are less concentrated. Requires no work, results from random kinetic energy motion of atoms and the universla tendency of order to deteriorate into disorder. |
| Passive Transport | The diffusion of a substance across a biological membrane. Requires no energy. |
| Concentration Gradient | The level of concentration from High to Low. |
| Osmosis | Diffusion of water molecules across a selectively permeable membrane. Also a type of Passive Transport. |
| Hypertonic | The solution with the higher concentration. |
| Hypotonic | The solution with the lower solute concentration. |
| Osmoregulation | The control of water balance. The animal must have a way to prevent excessive uptake or loss of water. |
| Facilitated Diffusion | When a protien makes it possible for a substance to move down its concentration gradient. Without the protien the substance would not cross the membrane, or diffuse to slowly to be useful to the cell. |
| Active Transport | Requires the cell to expend energy to move molecules across a membrane. A transport pump actively pumps a specific solute against the solutes concentration gradient. |
| Exocytosis | Used by a cell to to export bulky materials form its cytoplasm. In the first step of this process, a membrane-enclosed vesicle filled with macromolecules moves to the plasma membrane. Once there, the visicle fuses with the plasma membrane, and the vesicles contents spill out of the cell. |
| Endocytosis | The opposite of Exocytosis. A cell takes in macromolecules or other particles by forming vesicles or vacoules form its plasma membrane. |
| Phagocytosis | "Cellular Eating" An amoeba engulfs its prey by wrapping extensions called pseudopodia, around it and packaging it within a vacuoule. |
| Pinocytosis | "Cellular Drinking" The cell takes in droplets of fluid from its surrounding by using vesciles.. |
| Receptor-mediated Endocytosis | The plasma membrane indents to form a pit. The pit is lined with receptor protiens that pick up particular molecules form the surroundings. The pit will pinch closed to form a vesicle that will carry the molecules into the cytoplasm. |
| Hypercholesterplemia | A disease that infects about 1 in 500 babies in the world. Characterized by and excessively high amount of cholesterol in the blood. |
