Chapter 11: Thermodynamics and General Metabolism Flashcards
what is metabolism?
the mechanism of living cells to extract, convert and store energy from nutrients.
what is a metabolic pathway?
a series of enzyme-mediated reactions where the product of one reaction is used as the substrate in the next
what is Bioenergetics the study of?
study of how cells transform energy, often by producing, storing or consuming adenosine triphosphate (ATP)
what does ‘exergonic’ mean?
spontaneous
what does ‘endergonic’ mean?
non-spontaneous (the reverse/opposite rxn/interaction is spontaneous
does a negative delta H value mean that a rxn/interaction is favorable or UNfavorable?
favorable
is a positive delta S value mean that a rxn/interaction is favorable or UNfavorable?
favorable
if a rxn/interaction has a negative delta H value and a a postive delta S value, is the rxn/interaction favorable or UN favorable?
favorable
what 2 things does a negative delta G value mean?
- rxn/interaction is spontaneous
2. products have lower energy than substrates (equilibrium leans forward/towards products)
are metabolic processes usually spontaneous or NON spontaneous?
They’re usually NON spontaneous (but the non-sponteneity is overcome through coupling rxns)
what does it mean to ‘couple’ are rxn?
it means you combine a spontaneous rxn with a non-spontaneous rxn in order to drive the non-spontaneous rxn
the net energy of these couple rxns is negative?
why do living organisms use coupled rxns?
to drive otherwise non-spontaneous rxn (that are critical for viability)
is the first step of glycolysis an example of a coupled reaction?
yes
what is glycolysis?
metabolic process involving the break down of glucose
why it ATP so often used as part of coupled rxns?
there are 2 reasons
it is a very high energy molecule
release of each phosphate group is highly energetically favorable
what do you call the bond between the phosphate groups in ATP?
phosphoanhydride bond
what are 2 ways ATP is used in metabolism?
- cleaving its phosphate groups (energetically favorable) is coupled with/used to drive non-spontaneous rxns
- Phosphate groups are used as phosphate sources for phosphorylation rxns
what are 4 reasons it’s so energetically favorable to cleave phosphate groups off of ATP?
- ATP has localized negative charges whose charge-charge repulsion is reduced when phosphate groups are cleaved
- ADP and AMP have more resonance structures/more delocalization of charges than ATP
- Breaking ATP into multiple pieces increases entropy
- Breaking ATP into pieces results in better (favorable) solvation of each piece
when you hydrolyze an ATP, are the products lower in energy than the substrate?
yes
where do living organism get ATP?
they make it.
they break down larger molecules into smaller molecules to make ATP
what are 2 larger molecules whose breakdown can be coupled with ATP synthesis in order to offset the unfavorability of ATP synthesis?
phosphoenolpyruvate
1,3-Bisphosphoglycerate
why do we care about thioesters?
they have bonds that release energy similar to when you break the bonds in ATP
what is meant by ‘ATP production potential’?
describes the ability to produce ATP
are catabolic rxns oxidative or reducing?
oxidatitve
generally: oxidizing carbons
are anabolic rxns oxidative or reducing?
reducing
generally: oxidizing carbons
what is the significance of reduced NADH?
it has/stores extra electrons that can be used in ATP production
what is the difference between catabolic and anobolic metabolism?
catabolic breaks molecules down
anobolic builds molecules up
If a rxn’s enthaply is negative and entropy is positive (- +), at what temperatures is it spontaneous?
all temperatures
If a rxn’s enthaply is negative and entropy is negative (- -), at what temperatures is it spontaneous?
temperatures lower than T = delta H/delta S
If a rxn’s enthaply is positive and entropy is positive (+ +), at what temperatures is it spontaneous?
temperatures ABOVE T = delta H/delta S
If a rxn’s enthaply is positive and entropy is negative (+ -), at what temperatures is it spontaneous?
Never.
It is un-spontaneous at all temperatures
