unit 3 (topics 1-4) Flashcards
metabolism
all of the chemical reactions in an organism
metabolic pathways
series of chemical reactions that either build up (anabolic)/break down (catabolic) complex molecules
catabolic pathway
pathways that release energy by breaking down complex molecules into simpler ones
anabolic pathway
pathways that consume energy to build complicated molecules from simpler ones
energy
ability to do work
kinetic energy
energy associated with motion (thermal energy)
potential energy
stored energy (chemical energy)
law of thermodynamics
the study of energy transformations in matter; two laws
1st law of thermodynamics
-energy cant be created or destroyed
-energy can be transferred or transformed
2nd law of thermodynamics
-energy transformation increases the entropy (disorder) of the universe
-during energy transfers/transformations, some energy is unusable and often lost as heat
free energy
used to determine the likelihood of reactions in an organism (if they’re spontaneous or not), or if the reactions are energetically favorable
change in free energy = change in total energy-change in entropy
🔺G = 🔺H - T🔺S
exergonic reaction
- reactions that release energy (cellular respiration)
-🔺G<0 (negative G) - spontaneous
- drive endergonic reactions
endergonic reaction
- reactions that absorb energy (photosynthesis)
- 🔺G>0 (positive G)
- not spontaneous
ATP
- molecules use this as a source of energy to preform work
- couples exer/endergonic reactions to power cellular work
- organisms obtain energy by breaking the bond between the 2nd and 3rd phosphate in a hydrolysis reaction (phosphorylation: released phosphate moves to another molecule to give energy)
cells three kinds of work
MECHANICAL: movement (contraction of muscle cell, beating cilia, etc.)
TRANSPORT: pumping substances across membranes against spontaneous movement
CHEMICAL: synthesis of molecules (building polymers from monomers)
enzymes
- macromolecules (type of protein) that catalyze reactions by lowering the activation energy
- are not consumed by the reaction
enzyme structure/function
active site
allosteric site
induced fit
enzyme catabolism
enzyme anabolism
cofactors
coenzymes
inhibitors (permanent and reversable)
ACTIVE SITE: where enzyme binds to substrate
ALLOSTERIC SITE: where non-competitive enzymes go
INDUCED FIT: enzymes will change shape of active site to make substrates bind better
ENZYME CATABOLISM: enzyme helps break down complex molecules
ENZYME ANABOLISM: enzyme helps build complex molecules
COFACTORS: non-protein molecules that assist enzyme function (holoenzyme)
COENZYMES: organic cofactors
INHIBITORS: reduce activity of specific enzymes
–>PERMANENT: inhibitor binds with covalent bonds
–> REVERSIBLE: inhibitor binds with weak interactions
allosteric activator
substrate binds to the allosteric site and stabilizes the shape of the enzyme so that the active sites remain open
allosteric inhibitor
substrate binds to allosteric site and stabilizes the enzyme shape so the active sites are closed (inactive form)
cooperativity
substrate binds to one active site (on an enzyme with more than one active site) which stabilizes the active form
feedback inhibition
sometimes, the end product of a metabolic pathway can act as an inhibitor to an early enzyme in the same pathway
