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61 Cards in this Set

  • Front
  • Back
sum total of all the chemical concersions in a cell
link simple molecules to make complex ones - energy-storing reactions
anabolic reactions
break down complex molecules into csimpler ones - some provide the energy for anabolic reactions
catabolic reactions
cells must aquire this from their environment b/c they can't make it
can only be transformed molecular momvement and changes in chemical bonds - the ability to do work
energy of position - everything has it - stored energy
potential energy
energy of action - alters state or motion of matter
kinetic energy
energy is neither created nor destroyed - can be converted from one form to another - applies to open and closed systems
first law of thermodynamics
not all energy can be used & disorder tends in increase
second law of thermodynamics
usable energy + unusable energy =
total energy
G + TS =
unusable energy
usable energy
If ^G is + valence electrons, the reaction requires
an input of energy (anabolic reactions)
if ^G is - valence electrons, energy is
efficiency of energy used is dependant on
the system
some biological systems are very efficient but never
If products are more disordered than reactants, entropy has
capture, transfer and storage form of energy of cells - may be converted to other uses - building blocks for RNA and DNA
ADP + Pi + free energy -->
ATP + H2O -->
ADP+Pi (short for HPO42-)an inorganic phosphate ion
energy to make ATP comes from
the energy released from feul molecule ex: glucose
shuttles energy from exergonic reactions to drive endergonic reactionc
for a spontaneous reactions: the direction can be predicted, but not the likelihood or the rate of the reaction
energy barrier
energy needed to initiate a reaction
activation energy
lower the energy required of activation - don't cause a reaction to take place that couldn't take place w/o them
biological catalysts - mostly proteins (except ribozymes)
enzymes bind specific reactant molecules called
Enzyme + Substrate ---> enzyme-substrate complex --->
enzyme + products
the names of substrates reflect the _______ of their functions and often end w/ the suffix "______"
specificity, "-ase"
This enzyme catalyzes formation of RNA but not DNA
RNA polymerase
the site where substrates bind to the enzyme and catalysis takes place there - is only a small region of the whole protein
active site
bind specific substrates and catalyze particular reactions under certain conditions
active site
specificity for substrates comes from
3D shape, a.a. sequence, temp.,& othersolution or anvironmental conditions
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
effects rate of the reaction - rate of an uncatalyzed reaction is directly proportional to the conc. of the rectants
substrate concentration
the higher the _____ the more collisions & reactions per unit time - for catalysis reactions, this is true to a point
substrate concentration
when all enzyme active sites sre occupied
inorganic ions ex: copper, zinc, iron - bind temporarily to certain enzymes - essential to their function
permanently bound to enzymes ex: heme groups bound to the hemoglobin
prothetic groups
Carbon-containing molecules - some are vitamines - must react w/ an enzyme separate & then participate in in other reactions
examples of coenzymes
ATP & ADP, also substrates of the reactions
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
bind reversibly to an enzyme's active site - natural - compete w/ the substrate for binding site
competitive inhibitors
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
non-competitive inhibitors
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
irreversible inhibitors
have interacting subunits that change in shape and function and modulate their catalytic activity - controlled by effector/regulator molecules
Allosteric Enzymes
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
Allosteric Enzymes
has an acitve site that binds to the enzyme's substrate
catalytic subunit
has one or more allosteric sites that bind specific effector molecules
regulatory subunit
allosteric sites have 2 forms:
active site and inactive site
active sites can bind substrate
active state
allosteric sites can accept inhibitor
inactive state
switching off of a metabolic pathway by its end-product due to acess of the product
feedback inhibition
acts as an inhibitor of an enzyme within the pathway - prevents the waste of chemical resources
feedback inhibition
all enzymes have an optimal temp. for acitvity - the charges of COOH in neutral or basic solutions & NH2 in neutral or acidic solutions
an increase in _____ increases the rate of an enzyme-catalyzed reaction to a point
temp. can negatively influence shape by
breaking H bonds, interfering with ionic & hydrophobic interactions
if heat destroys enzyme it________
groups of enzymes that can catalyze the same reaction but have diff. chemical compositions & physical properties
______ is an example where most human enzymes are stable at higher temperatures then those of bacteria