3.1 Flashcards
When does a chemical reaction occur?
when atoms have enough energy to combine or change bonding partners
metabolism
sum of all the chemical reactions in a cell or organism at a given time
metabolic reactions involve energy changes
energy
capacity to do work or capacity for change
potential energy
energy of position
energy stored in an object (chemical bonds, concentration gradient, electric charge imbalance)
kinetic energy
energy of motion
energy that a moving object has
First Law of Thermodynamics
when energy is converted from one form to another, the amount of energy before and after the conversion is the same
energy is neither created nor destroyed
Second Law of Thermodynamics
when energy is converted from one form to another, some of that energy becomes unavailable to do work
some energy is lost to disorder
disorder increases with energy transformations
entropy
measure of disorder in a system
high entropy: high disorder, less order
low entropy: low disorder, more order
living organisms must have a constant supply of energy to maintain order/structure
total energy
sum of the useable energy that can do work and unusable energy that is lost to disorder
H = G + TS
G = H - TS
change in free energy
free energy (products) - free energy (reactants)
if G > 0, the products have greater energy
if G < 0, the reactants have greater energy
exergonic reactions
G(products) < G(reactants)
delta G < 0
energy is released
endergonic reactions
G(products) > G(reactants)
delta G > 0
energy is consumed
factors of the change in free energy (Δ G)
ΔG = ΔH - TΔS
total energy is: added to the system (ΔH>0), released (ΔH<0)
disorder in products decreases (ΔS<0), increases (ΔS>0)
anabolic reactions
synthesize larger, more complex molecules from many smaller molecules
ΔG>0 - small molecules + free energy –> complex molecules
ΔS<0 - more disordered –> less disordered
catabolic reactions
break down large, complex molecules into smaller molecules
ΔG<0 - complex molecules –> smaller molecules + free energy
ΔS>0 less disordered –> more disordered
chemical equilibrium
balance between forward and reverse chemical reactions, a state of no net change
forward and reverse reactions proceed at the same rate
quantities of products and reactants remain constant (NOT equal)
relationship between ΔG and equilibrium
ΔG=0 at equilibrium
ΔG is near zero: readily reversible reaction
ΔG»0 or ΔG«0: fat from equilibrium, functionally irreversible
highly exergonic reactions favor products
highly endergonic reactions favor reactants
standard conditions: 25C. 1atm, 1M, pH 7
ATP
cells use adenosine triphosphate for the capture and transfer of free energy
ATP releases energy during hydrolysis
ATP can phosphorylate to other molecules, which gain some energy
hydrolysis of ATP
ATP + H2O –> ADP + Pi + free energy
highly exergonic
energy is stored in the P~O bonds
ADP and Pi are more stable than ATP
formation of ATP
ADP + Pi + free energy –> ATP + H2O
endergonic and consumes as much free energy as is released by the hydrolysis of ATP
ATP coupling
ADP picks up energy from exergonic reactions to become ATP, which then donates energy to endergonic reactions
relationship between endergonic and exergonic reactions
coupling of exergonic and endergonic reactions allows energy releases from exergonic reactions to drive endergonic reactions
