Biology
Chapter 4
Chapter 4
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Flashcards
reactions become more spontaneous how
if their activation energy is lowered
when reactions activation energy is lowered it is called...
catalysis
catalyzed reactions proceed faster or slower than non-catalyzed reactions?
faster
reactions rates are in balance when?
at chemical equilibrium
2 things aobut chemical equilibrium
rates of product and reactant formation are equal ///// does not mean the amounts of products and reactants are equal; the rates of formation are equal
linked oxidation and reduction reactions form what?
election transport chains
what reactions transfer energized electrons from 1 molecule to another?
oxidation-reduction reactions (redox reactions)
2 characteristics of oxidation
loss of electrons and releases energy
2 characteristics of reduction
gains electrons and requires energy
what drives reactions forward?
high reactant concentration
when are forward and reverse reactions occuring at the same rate
equilibrium
what drives reactions in reverse
high product concentration
what is cellular energy currency of life
ATP (adenosine triphosphate)
2 characteristics of ATP
its a type of nucleotide and mitochondria produce ATP
what is an energy carrier in cells?
ATP
all cells depend on what?
the potential energy in ATP
ATP links what?
endergonic to exergonic reactions
coupled reactions do what?
release and store energy in ATP
what completes the energy transaction?
a transfer of phosphate
what two effects happen when the transfer of phosphate completes the energy transaction
1. may energize target molecule (more likely to bond with another molecule)
2. change in shape of target molecule
what happens when target molecule is energized?
it fuels the endergonic reaction
what happens when a change in shape of a target molecule happens during the transfer of phosphate?
it is used to move substances-muscle contraction results
ATP represents what?
short-term energy storage
2 billion/minute
ATP short term energy storage
organisms recycle ATP how fast?
at a furious pace
Do cells stockpile ATP?
no
when cells do not stockpile ATP - phosphate bonds are what?
unstable
cells store what energy-rich molecules
fats, starch and glycogen
what speeds up biochemical reactions
enzymes
organic molecule that catalyzes a chemical reaction without being consumes
enzyme
most enzymes are....
proteins
do enzymes higher or lower the energy of activation
lower
how many enzymes per cell?
thousands
3 characteristics of enzymes
lower the energy of activation, there are thousands per cell and they recognize, alter, and bind specific reactants
where do substrates bind?
at the active site
what are enzyme partners
cofactors-atoms/molecules other than proteins
characteristics of cofactors-atoms/molecules other than proteins
must be present for enzyme to work
often oxidized or reduced
not consumed
vitamins - coenzyme - organic cofactor
reaction rates are controlled by
cells
reaction inhibits enzyme that controls its formation is a characteristic of what?
negative feedback/feedback inhibition
two types of inhibition
competitive
noncompetitive
