Lesson 9: Introduction to Metabolism Flashcards
some types of metabilism
- glycolysis, TCA, fermentation
- transcription, translation, purine recycling
linear pathways
A <> B <> C <> D
branched pathways
A <> B <> C <> D –> E and –> F
catabolism
- breakdown pathways. high energy molecules –> low energy molecules (ex: glucose -> CO2)
- oxidative, produce energy, strip H+ and e- away from reduced “fuels”
anabolism
- biosoyntheic pathways. Low energy molecules –> high energy molecules
- reductive, consume energy, utilize H+ and e- from catabolism
more on catabolism
- produces energy
- generates monomers
- produces reduced coenzymes
- (e-)
OVERALL: net oxidative
more on anabolism
- uses energy
- uses monomers
- uses reduced coenzymes
- (e-)
OVERALL: net reductive
are many biomolecules and primary metabolites shared
YES
near equilibrium rxn
easily reversible under cellular conditions
far from equilibrium rxn
essentially irreversible under cellular conditions
— big delta G
what could be the advantage of having both near and far from equilibrium rxns in the cell
sharing enzymes –> minimizing # of enzymes that the cell needs to have
if delta H is negative (favorable) and delta S is positive (favorable) then
delta G will be negative/exergonic and will be spontaneous because its negative at all temperatures
if delta H is positive (unfavorable) and delta S is negative (unfavorable) then
delta G will be positive/endergonic and will not be spontaneous because delta G is positive for temperatures
if delta H is negative (favorable) and delta S is negative (unfavorable) then
delta G will be negative when T is low (T< DeltaH/DeltaS) and positive when T is high (T > deltaH/DeltaS)
– spontaneous when delta G is negative
if delta H is positive (unfavorable) and delta S is positive (favorable) then
delta G will be negative when T is high and positive when T is low
- spontaneous only when delta G is negative (when T > delta H/delta S
K’eq far
10^2 and up
10^-2, 10^-3 (keep getting neg) and so on…..
K’eq near
between 10^1 and 10^-1
kJ/mol near
around -6 to 6 Kj
unfavorable rxns (endergonic) occur in cells by
coupling them to favorable reactions
source of Gibbs free energy in terms of molecular structure
- repulsive forces between negatively charged phosphate groups (more stable: negative charges allowed to get further away)
- resonance stabilixation of phosphate = having good leaving group resulting in low E of products compared to reactants
high energy compounds
adenosine triphosphate (ATP; thioesters, acyl-phosphates, GTP
hydrolysis
- relieves electrostatic repulsion between negative charges between B and Y phosphoryl group
- the hydrolysis products are better resonance stabilized and therefore lower in energy
free energy of hydrolysis for thioesters and oxygen esters:
another ay to visualize the concept of “high energy” compounds
– add H2O across bond — increases stability
electron carrying compounds
NAD+ and FAD
— electrons have to go somewhere when they are being stripped away => they go to these reducing agents
NAD+ reducing
NAD+ (ox) + 2 e- + 2 H+ –> NADH )red_ + H+
FAD reducing
FAD (ox) + 2e- + 2H+ –>? FADH2 (red)
