metabolism Flashcards
what are metabolites?
chemical intermediates in metabolic pathways
True or False: all pathways share the same functional chemical and thermodynamic principles
TRUE
what are the 2 major purposes of metabolism?
1) obtain usable chemcial energy from the environment
2) make molecules that cells need to survive
what is an anabolic pathway? what characteristics does it have?
processes that USE energy to build larger molecules
-reductive
-bonds are made using electrons
what is a catabolic pathway? what characteristics does it have?
processes that RELEASE energy in breaking down molecules
-oxidative
-electrons are removed as bonds are broken
what is an amphibolic pathway?
a process that operates in catabolic and anabolic ways
-depends on the condition
in what metabolic process are co-factors reduced?
catabolism
in what metabolic process are cofactors oxidized?
anabolic
how are excess carbs stored?
stored as glycogen in the liver and skeletal muscle
how are excess FA stored?
stored as fat (triacylglycerols) in adipocytes (fat cells)
what is typically the end product for oxidation of carbon molecules?
CO2
what is the difference between standard free energy and actual free energy?
standard free energy is a thermodynamic term indicating the reaction is proceeding at standard conditions
Actual free energy change depends on the [substances] in the system
if the change in free energy for a rxn is ~0, what does this indicate?
the reaction is reversible
-system is close to equilibrium
if the change in free energy for a rxn is «<0, what does this indicate?
the rxn is irreversible
how does changes in [product] vs [reactant] change the direction of the rxn?
increases in [product] will favour the reverse
increases in [reactant] will favour forward rxn
are reversible or irreversible steps usually regulated?
irreversible
-E1/ E4 are regulated
what is the rate-limiting step in a reaction?
the irreversible regulated reaction that determines the overall rate of the pathway
what are 2 examples of inhibition in metabolic pathways?
1) product inhibition
-enzyme inhibited by the product formed from that rxn
2) feedback inhibition
-enzyme inhibited by a metabolite further down the pathway
what is feed-forward activation?
activation of an enzyme upstream due to a metabolite being produced
what is reciprocal regulation? why is it important?
regulation where opposing pathways catalyze the revers of another pathway
-pathways are regulated in order to ensure that both do not operate at the same time
what is considered to be a high energy molecule?
compounds that have usable chemical energy
- rxn associated with a large delta G
what are three maojor types of high energy intermediates?
1) electron carriers
-NADH, NADPH,FADH2
2) nucleoside triphosphate
-ATP,UTP,GTP
3) thioesters
what are 3 characteristics of oxidative rxn’s?
1) metabolites oxidized
2) cofactors are reduced (typically NAD+ or FAD)
3) catabolic rxn
what are 3 characteristics of reductive rxn’s?
1) metabolites reduced
2) cofactors are oxidized (typically NADPH)
3) anabolic rxn
