Lecture 11 Flashcards
Proton motive force equation
ΔG= [concentration across membrane] or ΔpH ) + Zf ΔΨ(voltage across membrane)
Concentration differences provides energy for protons to move back down and contribute to the free energy
Source of energy on ETC
proton gradient creates an electrochemical potential- it literally has voltage, energy stored here used to make ATP
ATP synthase, F0 and F1 function
ATP synthase: allows H+ back into matrix coupling mechanism
F0: protons move through this mechanism and the energy shapes F1 into diff confirmations
F1: has 3 α, β that can bind ATP or ADP & Pi, conformations of these cause a rotary motion and drive ATP synthesis.
weak acid uncouplers effect on:
ATP synthesis
O2 consumption
proton gradient
ATP synth: drops drastically
O2 consumption: continues
proton gradient: breaks it down by passive diffusion. the protonated form of acid is hydrophobic enough (& neutral) to cross the IM and carry protons
ATP synthesis and O2 consumption were uncoupled
ATP synthase inhibition
leads to no gradient==no ATP produced O2 production also stops
why so many transporters in the mitochondrial inner membrane?
Because it is very impermeable, so in order to get different things in, we need transporters
ATP synthase, F0 and F1 location
F0: embedded in membrane
F1: in the matrix
ATP synthase inhibitors effect on:
ATP synthesis
O2 production
proton gradient
ATP: stops ATP synthesis
O2 consumpt: stops this aswell because they are coupled
Proton gradient: no flow, enzyme rxn, no gradient
Inhibition of individual complexes effect on:
ATP synthesis
O2 consumption
Proton gradient
Stops and inhibits all, because all the reactions are coupled
Proton gradient is product of ___ and drives ___
ETC —> PH+ —> Ox phosphorylation
adding adp then succinate leads to O2 consumption and ATP synthesis
Shows coupling
Adding succinate first leads to no O2 consumption.
If you have e- source but no ADP, you will get no flow—reinforces the coupling idea
Weak acid uncouples O2 consumpt & ATP synth. there is still great e- flow but there is no longer a need for ATP synthesis.
Glycerol 3-Phosphate shuttle
*NOT G3P from glyclysis
Transport e- from cytosol to matrix
takes NADH (that was from glycolysis) dumps e- into DHAP to make Glycerol-3P→ gets converted back to DHAP and e- go to another enzyme that dumps them to Q.
So this enters at complex II level
Malate-Aspartate shuttle
Characters: Amino Acids or Ketones
- 2 cotransporters
- Malate in αKG out
green arrow, transfer of nitrogen from amino acid to ketone
Overall: e- carrying process w/ set of transaminations between OAA, Asp, αKG/ Glutamate
α keto acids have
cognate α amino acids
ex: pyruvate & alanine
basically the same except for the ketone part is replaced by the amino group
thermogenins
uncoupling proteins (uncouple ATP synthesis & e- transport) that sit on the membrane and allow e- back into the membrane, skewing the gradient. Thus generating HEAT
Allow to burn energy without doing anabolism
could also be an answer to obesity problems
thermogenins
brown adipose tissue
loaded with mitochondria which is uncoupled with UCP1 (uncoupling protein) and tremendously involved in generating heat
Found in babies and infants to keep them warm
which shuttle mechanism produces 3 ATP?
Which produces 5 ATPs?
3: Glycerol-2 phosphate
5: Malate-aspartate
Why are shuttles important to continue glycolysis
they transport e- back into the membrane, in other words NADH produced from glycolysis has to get back inside the matrix in order to be used up by the Krebs cycle, otherwise it is useless
Acceptor Control
Pathways (glycolysis, Krebs, oxid-phosph) controlled by the availability of ADP.
because when ADP runs out, there is a build-up of products that activate allosteric regulation and adjusts proceses to how much ADP is available
