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60 Cards in this Set

  • Front
  • Back
capacity to do work
first law of thermodynamics
any isolated system has a finite amount of energy that cannot be added or lost
second law of thermodynamics
entropy, or disorder of the universe always increases
energy in
energy release
adenosine triphosphate
gives up a phosphate group to other molecules and primes them to react
phosphate group transfers
adenosine diphosphate
forms when ATP gives up phosphate group, can reform to ATP when it binds to inorganic phosphate
Cycle which drives most metabolic reactions
starting substances in a metabolic reaction
substances found during a reaction sequence
substances left at the end of a reactions sequence
catalysts that speed specific reactions enormously
energy carriers
activate enzymes and other molecules by making phosphate group transfers
transport proteins
helps solutes across membranes
chemical equilibrium
reaction rate is about the same in both directions
oxidation-reduction reactions
"redox reactions" in which cells release energy efficiently by electron transfers
"redox" reactions
one molecule gives up electrons and another gains them
electron transfer chains
membrane-bound arrays of enzymes and other molecules that accept and give up electrons in sequence
metabolic pathways
enzyme-mediated sequences of reactions in cells
biosynthetic pathways
sequences that require energy inputs
degrative pathways
sequences that break down molecules into smaller, lower energy products
activation energy
the minimum amount of internal energy that molecules must have before a reaction gets going
reactants taht bind to a specific enzyme
active sites
pockets or crevices where substrates bind and where specific reactions are catalyzed
functional group transfers
one molecule gives up a functional group to another
electron transfers
one or more electrons stripped from one molecule are donated to another
juggling of internal bonds converts one molecule to another
two molecules are covalently bound together as a larger molecule
larger molecule splits into smaller ones
transition state
time in a reaction at which a bonds are at a breaking point and the reaction can run easily to product
induced-fit model
substrateis not quite complementary to an active site, so enzyme bends and optimizes fit, and so pulls the substrate to the transition state
a cofactor, a class of organic compounds that may or may not have a vitamin component
help neutralize free radical
help out at the active site of enzymes or taxi electrons,
specific metal ions or coenzymes
free radicals
atoms with unpaired electrons, reactive, unbound fragments left over from reactions
allosteric site
alternate site on enzyme where a molecule binds to the enzyme to act as an inhibitor or activator
feedback inhibition
a change that results from a specific activity shuts down the activity
selective permeability
molecular structure that allows some substances but not others to cross it in certain ways, at certain tiems
concentration gradient
difference in the number per unit volume of ions or molecules of a substance between adjoining regions
net movement of like molecules or ions down a concentration gradient
electric gradient
difference in electric charge between adjoining regions
pressure gradient
difference in exerted force per unit of area in two adjoining regions
passive transports
"facilitated diffusion", simply allowing a substance to follow its concentration gradient across a membrane
active transport
energy-driven protein motors help move a specific solute across membrane against the concentration gradient
fusion of the plasma membrane and a membrane-bound vesicle that formed inside the cytoplasm
inward sinking of a patch of plasma membrane, which seals back on itself to form a vesicle inside the cytoplasm
calcium pump
active transporter that helps keep the concentration of calcium in a cell at least a thousand times lower than the outside
sodium-potassium pump
active transporter that mediates teh movement of sodium ions from the cytoplasm into the open channel to bind to functional groups, so that the ATP can prompt the pump to change shape and release the sodium ions outside the cell
bulk flow
mass movement of one or more substances in response to pressure, gravity, or another external force
diffusion of water across a selectively permeable membrane
the relative solute concentrations of two fluids
hypotonic solution
when two fluids on opposing sides of a membrane differ in solute concentrations, the side with less solutes
hypertonic solution
when two fluids on opposing sides of a membrane differ in solute concentrations, the side with more solutes
isotonic solutions
no net osmotic movement
hydrostatic pressure
force that any volume of fluid exerts against a wall, a membrane, or some other structure enclosing it
osmotic pressure
amount of force preventing any further increase in volume
receptor-mediated endocytosis
receptors at the membrane bind to molecules of a hormone, vitamin, mineral, or another substance
phagocytosis endocytosis
common endocytic pathway in which phagocytes such as amoebas englulf the microbes, food particles, or cellular debris
bulk-phase endocytosis
not as selective, vesicle forms around a small volume of the extracellular fluid