Chapter 6 (Metabolism: Energy and Enzymes)

This set deals with words from Chapter 6 (Metabolism: Energy and Enzymes)
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active site
region of the surface of an enzyme where the substrate binds and where the reaction occurs
ADP (adenosine diphsosphate)
nucleotide with two phosphate groups that can accept another phosphate group and become ATP
ATP (adenosine triphosphate)
nucleotide with three phosphate groups; the breakdown of ATP into ATP + P makes energy available for energy-requiring processes in cells
chemical energy
energy associated with the interaction of atoms in a molecule
chemiosmosis
ability of certain membranes to use a hydrogen ion gradient to drive ATP formation
coenzyme
nonprotein organic molecule that aids the action of the enzyme to which it is loosely bound
cofactor
nonprotein adjunct required by an enzyme in order to function; many are metal ions, others are coenzymes
competitive inhibition
form of enzyme inhibition where the substrate and inhibitor are both able to bind to the enzyme's active site; each complexes with the enzyme; only when the substrate is at the active site will product form
coupled reactions
reactions that occur simultaneously; one is an exergonic reaction that releases energy, and the other is an endergonic reaction that requires an input of energy in order to occur
denatured
loss of an enzyme's normal shape so that is no longer functions; caused by a less than optimal pH and temperature
electron transport chain
passage of electrons along a series of membrane-bound electron carrier molecules from a higher to lower energy level; the energy released is used for the synthesis of ATP
endergonic reaction
products have more free energy than reactants
energy
capacity of do work and bring about change; occurs in a variety of forms
energy of activation
minimum amount of energy that must be added into a reaction in order for molecules to react with one another and start a reaction
entropy
energy lost from doing useful work; a measure of disorder or randomness; ex energy lost to heat
enzyme
organic catalyst, usually a protein, that speeds a reaction in cells due to its particular shape
enzyme inhibition
means by which cells regulate enzyme activity; may be competitive or noncompetitive inhibition
exergonic reaction
products have less free energy than reactants
feedback inhibition
mechanism for regulating metabolic pathways in which the concentration of the product is kept within a certain range until binding at an allosteric site shuts down the pathway, and no more product is produced
free energy
the amount of energy available to perform work; also called Gibbs free energy (DG)
heat
type of kinetic energy; captured solar energy eventually dissipates as heat in the environment
induced fit model
change in the shape of an enzyme's active site that enhances the fit between the active site and its substrate(s)
kinetic energy
energy that is actually doing work
law of conservation
energy cannot be created or destroyed but can only be changed from one form to another
mechanical energy
a type of kinetic energy, such as walking or running
metabolic pathway
series of linked reactions, beginning with a particular reactant and terminating with an end product
metabolism
all of the chemical reactions that occur in a cell during growth and repair
NAD+ (nicotinamide adenine dinucleotide)
coenzyme of oxidation-reduction that accpets electrons and hydrogen ions to become NADH + H+ as oxidation of substrates occurs; during cellular respiration, it carrie electrons to the electron transport chain in mitochondria
NADP+ (nicotinamide adenine dinucleotide phosphate)
coenzyme of oxidation-reduction that accepts electrons and hydrogen ions to become NADPH + H+; during photosynthesis it participates in the reduction of carbon dioxide to glucose
noncompetitive inhibition
form of enzyme inhibition where the inhibitor binds to an enzyme at a location other than the active site; while at this site, the enzyme shape changes, the inhibitor is unable to bind to its substrate, and no product forms
oxidation
loss of one or more electrons from an atom of molecule; in biological systems, generally the loss of hydrogen atoms
phosphorylation
in metabolic processes, a way to activate an enzyme in which the enzyme either attaches an inorganic phosphate to a molecule or mediates the transfer of a phosphate group from one molecule to another
chemical potential energy
stored energy
product
substance that forms as a result of a reaciton
reactant
substance that participates in a reaction
reduction
gain of electrons by an atom or molecule with a concurrent storage of energy; in biological systems, the electrons are accompanied by hydrogen ions
substrate
reactant in a reaction controlled by an enzyme
vitamin
essential requirement in the diet, needed in small amounts; often part of enzymes as a cofactor
Second law of thermodynamics
energy cannot be changed from one form to another without a loss of usable energy
membrane
sites where chemical reactions can occur in an orderly matter
Adenosine triphosphate
high energy compound used to drive metabolic reactions
Adenosine diphosphate
ATP is constantly being generated from
Adenosine + ribose =
adenosine
in ADP, how many phosphate groups are there?
three
During a coupled reaction, the bond joining a phosphate group is broken by
hydrolysis
in the ATP cycle, the energy from exergonic reactions can be summed up by
respiration
in the ATP cycle, the energy for endergonic reactions goes to do
cellular work
chemical work
energy needed to synthesize macromolecules
transport work
energy needed to pump substances across plasma membrane
mechanical work
energy needed to contract molecules, beat flagella, etc
lowering energy barriers
enzymes speed up the cell's chemical reactions by
1 substrate and 2 products
In a hydrolysis type of reaction there are....
2 substrates and 1 product
In a dehydration synthesis type of reaction there are....
substrate concentration
enzyme activity increases with this; more collision between substrate molecules and the enzyme
temperature
enzyme activity increases with this; too much can destroy them
pH
most enzymes are optimized for a particular type of this
reversible enzyme inhibition
when a substance known as an inhibitor binds to an enzyme and decreases its activity
competitive inhibitor
takes the place of a substrate in the active site
noncompetitive inhibitor
alters an enzyme's function by changing its shape
irreversible inhibition
materials irreversibly inhibit an enzyme (known as poisons)
cyanides
inhibit enzymes resulting in all ATP production
heavy metals
irreversibly bind with many enzymes
nerve gas
irreversibly inhibits enzymes required by nervous system
certain pesticides
too toxic to insects because they inhibit key enzymes in the nervous system
many antibodies
inhibit enzymes that are essential to the survival of disease-causing bacteria
penicillin
inhibits an enzyme that bacteria use in making cell walls
transition state
a temporary energy level of a chemical reaction's reactants where bonds have reached their breaking points and new bonds are ready to form
catabolic pathway
a metabolic pathway in which energy is released and complex molecules are broken down into simpler molecules
anabolic pathway
a metabolic pathway in which energy is supplied so simple molecules are formed into complex molecules