Biology Cambell Reese
Terms : Hide Images
| 546039689 | metabolism | the total of an organism's chemical reactions; an emergent property of life that arises from interactions between molecules within the orderly environment of the cell | |
| 546039690 | metabolic pathway | begins with a specific molecule, which is then altered in a series of defined steps, resulting in a specific product; each step of teh pathway is catalyzed by a specific enzyme | |
| 546039691 | catabolic pathway | a metabolic process that breaks down complex molecules into simpler compounds; example = cellular respiration because it breaks glucose into carbon dioxide and water; the energy that is stored becomes available to do work within the cell | |
| 546039692 | anabolic pathway | a metabolic process that consumes energy to build complicated molecules from simpler molecules; example = synthesis of a protein from amino acids; energy comes from catabolic pathways | |
| 546039693 | bioenergetics | the study of how energy flows through living organisms | |
| 546039694 | energy | the capacity to cause change | |
| 546039695 | kinetic energy | the relative motion of an object | |
| 546039696 | heat energy | kinetic energy associated with random movement of atoms or molecules | |
| 546039697 | potential energy | the energy that matter possesses because of its location or structure when it is at rest; due to arrangement of atoms | |
| 546039698 | chemical energy | the type of energy that refers to the potential energy available for release in a chemical reaction; glucose, for example, has a high amount of this | |
| 546039699 | thermodynamics | the study of energy transformations that occur in a collection of matter | |
| 546039700 | first law of thermodynamics | a rule that states that the energy of the universe is constant; energy can be transferred and transformed, but it cannot be created or destroyed | |
| 546039701 | second law of thermodynamics | a rule that states that every energy transfer or transformation increases the entropy (disorder) of the universe; unstoppable trend toward randomization of the universe as a whole | |
| 546039702 | free energy | the portion of a system's energy that can perform work when temperature and pressure are uniform throughout the system, as in a living cell; this type of energy is a measure of a system's instability, meaning its tendency to change to a more stable state | |
| 546039703 | entropy | disorder of the universe | |
| 546039704 | enthalpy | order of the universe | |
| 546039705 | +G | the variable of free energy that represents a generally unstable system | |
| 546039706 | -G | the variable of free energy that represents a generally stable system | |
| 546039707 | exergonic | the type of reaction that proceeds with a net release of free energy; because the chemical mixture loses free energy, Gibbs free energy is negative; it is a spontaneous reaction | |
| 546039708 | endergonic | the type of reaction that absorbs free energy from surroundings; because energy is stored in molecules, Gibbs free energy is positive; the reaction is nonspontaneous | |
| 546039709 | chemical work | the type of cellular work that includes the pushing of endergonic reactions, which would not occur spontaneously, such as the synthesis of polymers from monomers | |
| 546039710 | transport work | the type of cellular work that includes the pumping of substances across membranes against the direction of spontaneous movement | |
| 546039711 | mechanical work | the type of cellular work that includes the beating of cilia, the contraction of muscle cells, and the movement of chromosomes during reproduction | |
| 546039712 | energy coupling | the use of an exergonic process to drive an endergonic one; ATP is responsible for mediating this, and it acts as an energy source | |
| 546039713 | ATP | this molecule is composed of ribose, adenine, and a chain of three phosphate groups | |
| 546039714 | phosphorylated | the state of a molecule when it receives a phosphate, such as in ATP hydrolysis, making it more reactive (less stable) than the original molecule | |
| 546039715 | enzyme | a macromolecule that acts as a catalyst; without this, pathways of metabolism would be congested because reactions would take so long | |
| 546039716 | catalyst | a chemical agent that speeds up a reaction without being consumed by the reaction; enzymes are examples of these | |
| 546039717 | activation energy | the initial investment of energy for starting a reaction; the energy required to destabilize the reactant molecules so their bonds can break; also, the amount of energy needed to push reactants over a "hill" so that the "downhill" part of the reaction can begin | |
| 546039718 | substrate | the reactant an enzyme acts on | |
| 546039719 | enzyme-substrate complex | the entity that forms when an enzyme bonds to a substrate, in which the enzyme's catalytic reaction converts the substrate to the product of the reaction | |
| 546039720 | active site | a pocket or groove on the surface of an enzyme where catalysis occurs; there is only one of these per enzyme; this is formed by a few amino acids while others construct a frame for it | |
| 546039721 | intermediate | a molecule in a metabolic pathway that is a product in one step and used as a reactant in another step; it can be crossed out from the overall equation | |
| 546039722 | ATP --> ADP + P(i) | the equation for the hydrolysis of ATP | |
| 546039723 | -7.3 kcal/mol | the amount of Gibbs free energy that results from the hydrolysis of ATP | |
| 546039724 | ADP + P(i) --> ATP + H2O | the equation for the synthesis of ATP | |
| 546039725 | +7.3 kcal/mol | the amount of Gibbs free energy that results from the synthesis of ATP | |
| 546039726 | C6H12O6 + 6O2 --> 6CO2 + 6H2O | the equation for aerobic cellular respiration | |
| 546039727 | -686 kcal/mol | the amount of Gibbs free energy that results from aerobic cellular respiration | |
| 546039728 | first step | in this step of catalysis, the substrate enters the active site; the enzyme changes shape so the active site can enfold the substrate | |
| 546039729 | second step | in this step of catalysis, the substrate and enzyme bond via weak bonds | |
| 546039730 | third step | in this step of catalysis, the active site lowers the activation energy for the reaction | |
| 546039731 | lower activation energy | doing these things: a) acting as a template for substrate orientation, b) stressing the substrates and stabilizing the transition state, c) providing a favorable microenvironment, and d) participating directly in catalytic reaction, are ways to do what in a reaction? | |
| 546039732 | saturated | the state that an enzyme is said to be in if as soon as the product of one reaction leaves, a new substrate enters the active site | |
| 546039733 | cofactors | nonprotein helpers for catalytic reactions; these may be bound tightly to an enzyme as a permanent resident, or may be bound loosely and reversibly along the substrate | |
| 546039734 | coenzyme | cofactors that are inorganic; examples of these are vitamins | |
| 546039735 | enzyme inhibitors | chemicals that selectively reduce or prevent the action of a specific enzyme | |
| 546039736 | competitive inhibitors | reversible inhibitors that resemble the normal substrate molecule and compete for admission into the active site; these reduce productivity by blocking substrates from entering active sites; these can be overcome by producing more substrates to outnumber them; poisons are an example of these with strong bonds | |
| 546039737 | competitive inhibition | this occurs when a molecule that resembles substrate bonds to the active site, thereby blocking the substrate; this occurs with weak bonds; the higher the concentration of the inhibitor, the slower the reaction; not used intentionally | |
| 546039738 | noncompetitive inhibitors | these molecules do not directly compete with substrates--instead, they bind to another part of the enzyme, causing it to change its shape so that the active site becomes less effective at conversion | |
| 546039739 | allosteric regulation | this occurs when a molecule bonds to some other location on an enzyme, causing a conformational change, which blocks the active site; after the molecule leaves, however, the enzyme returns to its original shape; may result in either inhibition or enhanced activity of an enzyme | |
| 546039740 | allosteric site | the alternate location on an enzyme where noncompetitive inhibitors bond | |
| 546039741 | encourages | a -G with the addition of a catalyst ________________ the reaction | |
| 546039742 | discourages | a -G with no addition of a catalyst ________________ the reaction | |
| 546039743 | encourages | a +G coupled with an exergonic reaction and with the addition of a catalyst ____________ the reaction | |
| 546039744 | discourages | a +G without a coupled reaction and without a catalyst ________________ the reaction | |
| 546039745 | -G | the change in G for an exergonic reaction (energy outward) | |
| 546039746 | +G | the change in G for an endergonic reaction (energy inward) | |
| 546039747 | transition state | the state of a reaction at which just enough energy is reached to break the bonds of reactants | |
| 546039748 | cooperativity | a mechanism that amplifies the response of an enzyme to a substrate by leading one substrate molecule to prime an enzyme's acceptance of additional substrate molecules; when one subunit of an enzyme has an induced fit, other subunits mimic that fit; example = hemoglobin: as soon as one oxygen bonds to a heme group within the polypeptide chain of hemoglobin, the other three polypeptide chains develop a greater affinity to oxygen | |
| 546039749 | feedback inhibition | an occurrence in which a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway; this prevents the cell from wasting chemical resources; when an end product stops or slows its own production | |
| 546039750 | mitochondria | where enzymes for cellular respiration are found within a cell | |
| 546039751 | lock-and-key | the model for enzymes that says that enzymes are highly specific, and as a result, there is only one substrate that fits in an enzyme's active site; criticism: because proteins can be denatured, it is somewhat unlikely that rigid guidelines can be followed exactly | |
| 546039752 | induced fit | the model for enzymes that says that as the substrate and active site approach each other, each influences the other's shape so they mold together; compared to a proper handshake: both entities conform to make a good grip in order to interact | |
| 546039753 | necessities for a reaction | 1) molecules must collide, 2) molecules must collide with sufficient energy, 3) molecules must collide with proper orientation | |
| 546039754 | 35-40 | optimal temperature range for enzymes in the human body (in degrees Celsius) | |
| 546039755 | 6-8 | optimal pH range for enzymes in the human body |
