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61 Cards in this Set
- Front
- Back
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sum total of all the chemical concersions in a cell
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metabolism
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link simple molecules to make complex ones - energy-storing reactions
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anabolic reactions
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break down complex molecules into csimpler ones - some provide the energy for anabolic reactions
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catabolic reactions
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cells must aquire this from their environment b/c they can't make it
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energy
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can only be transformed molecular momvement and changes in chemical bonds - the ability to do work
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energy
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energy of position - everything has it - stored energy
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potential energy
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energy of action - alters state or motion of matter
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kinetic energy
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energy is neither created nor destroyed - can be converted from one form to another - applies to open and closed systems
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first law of thermodynamics
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not all energy can be used & disorder tends in increase
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second law of thermodynamics
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usable energy + unusable energy =
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total energy
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G + TS =
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H=
(enthalpy) |
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TS
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unusable energy
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G
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usable energy
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If ^G is + valence electrons, the reaction requires
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an input of energy (anabolic reactions)
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if ^G is - valence electrons, energy is
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released
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efficiency of energy used is dependant on
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the system
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some biological systems are very efficient but never
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100%
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If products are more disordered than reactants, entropy has
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increased
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capture, transfer and storage form of energy of cells - may be converted to other uses - building blocks for RNA and DNA
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ATP
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ADP + Pi + free energy -->
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ATP + H2O
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ATP + H2O -->
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ADP+Pi (short for HPO42-)an inorganic phosphate ion
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energy to make ATP comes from
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the energy released from feul molecule ex: glucose
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shuttles energy from exergonic reactions to drive endergonic reactionc
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ATP
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for a spontaneous reactions: the direction can be predicted, but not the likelihood or the rate of the reaction
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energy barrier
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energy needed to initiate a reaction
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activation energy
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lower the energy required of activation - don't cause a reaction to take place that couldn't take place w/o them
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catalysts
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biological catalysts - mostly proteins (except ribozymes)
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enzymes
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enzymes bind specific reactant molecules called
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substrates
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Enzyme + Substrate ---> enzyme-substrate complex --->
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enzyme + products
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the names of substrates reflect the _______ of their functions and often end w/ the suffix "______"
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specificity, "-ase"
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This enzyme catalyzes formation of RNA but not DNA
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RNA polymerase
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the site where substrates bind to the enzyme and catalysis takes place there - is only a small region of the whole protein
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active site
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bind specific substrates and catalyze particular reactions under certain conditions
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active site
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specificity for substrates comes from
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3D shape, a.a. sequence, temp.,& othersolution or anvironmental conditions
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lower activation energy requirements but do not affect equilibrium - do not alter the difference in free energy between the reactants and products - only alter the rate of the reaction
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catalysts
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effects rate of the reaction - rate of an uncatalyzed reaction is directly proportional to the conc. of the rectants
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substrate concentration
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the higher the _____ the more collisions & reactions per unit time - for catalysis reactions, this is true to a point
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substrate concentration
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when all enzyme active sites sre occupied
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saturated
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inorganic ions ex: copper, zinc, iron - bind temporarily to certain enzymes - essential to their function
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cofactors
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permanently bound to enzymes ex: heme groups bound to the hemoglobin
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prothetic groups
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Carbon-containing molecules - some are vitamines - must react w/ an enzyme separate & then participate in in other reactions
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coenzymes
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examples of coenzymes
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ATP & ADP, also substrates of the reactions
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can bind to enzymes, slowing down the rates of enzyme-catalyzed reactions - naturally occurring regulate metabolism - artificial ones can be used to treat disease, kill pests, or in the lab to study how enzymes work
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inhibitors
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bind reversibly to an enzyme's active site - natural - compete w/ the substrate for binding site
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competitive inhibitors
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bind reversibly to a site other than active site - artificial - change he shape of enzyme such that the active site no longer binds to the substrate
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non-competitive inhibitors
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destroy the enzyme's ability to interact w/ it's normal sunbstrate(s) ex: DIPF reacts w/ the OH group of the serines in the active site - eliminates the activity of acetylcholinesterase
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irreversible inhibitors
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have interacting subunits that change in shape and function and modulate their catalytic activity - controlled by effector/regulator molecules
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Allosteric Enzymes
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The binding of these changes the structure and function of the enzyme - may enhance or diminish reactions at the active site - some have more than one subunit
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Allosteric Enzymes
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has an acitve site that binds to the enzyme's substrate
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catalytic subunit
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has one or more allosteric sites that bind specific effector molecules
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regulatory subunit
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allosteric sites have 2 forms:
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active site and inactive site
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active sites can bind substrate
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active state
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allosteric sites can accept inhibitor
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inactive state
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switching off of a metabolic pathway by its end-product due to acess of the product
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feedback inhibition
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acts as an inhibitor of an enzyme within the pathway - prevents the waste of chemical resources
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feedback inhibition
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all enzymes have an optimal temp. for acitvity - the charges of COOH in neutral or basic solutions & NH2 in neutral or acidic solutions
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pH
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an increase in _____ increases the rate of an enzyme-catalyzed reaction to a point
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temperature
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temp. can negatively influence shape by
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breaking H bonds, interfering with ionic & hydrophobic interactions
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if heat destroys enzyme it________
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denatures
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groups of enzymes that can catalyze the same reaction but have diff. chemical compositions & physical properties
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Isozymes
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______ is an example where most human enzymes are stable at higher temperatures then those of bacteria
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fever
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