cell bio, exam 1 - free energy, biosynthesis, electron carriers

entropy

measure of a system’s disorder

• the universe will always tend towards disorder (spontaneous)

• systems need energy to decrease entropy and reverse it

cells maintain order but obey the second law of thermodynamics by

coupling energy-releasing, spontaneous, and favorable catabolic reactions with anabolic/biosynthetic pathways that require energy input; the net result of coupled reactions is more disordered

the standard free energy change (Delta G knot) is

the amount of disorder created in the universe that results from a reaction

• favorable reactions → negative

• unfavorable reactions → positive

cells obtain energy by [?] organic molecules

oxidizing

after an energetically favorable reaction occurs, energy is harnessed in chemical bonds of

an carrier; becomes active once energy is stored; able to store/bring energy to an anabolic reaction later

the reaction of ATP breaking into ADP and Pi

• is energetically favorable (negative delta G)

• hydrolysis reaction, involves water as a reactant

• releases energy

• ADP can be used again to make more ATP

the reaction of ADP and Pi being synthesized into ATP

• is energetically unfavorable (positive delta G)

• condensation reaction, involves water forming as a product

• consumes energy

• ATP is able to release energy again by breaking off the third phosphate

phosphorylation

the transfer of a phosphate group from one molecule like ATP to another

• these are all condensation reactions where water is formed as a product

• phosphate transfers are energetically favorable

enzymes catalyze reactions by

lowering activation energy/reducing energy input requirements

NADH and NADPH are activated electron carriers that carry energy in the form of

two high-energe e- and a proton H+ (creating a hydride ion, H-)

NAD+/NADP+ are the [?] form, NADH and NADPH are the [?] form

oxidized; reduced

conversion between the two forms allows the oxidation/reduction of target molecules

NADH and NADPH are structurally different, which does not change their electron-transfer properties, but changes their

ability to bind to specific enzymes and deliver e- to different molecules