lecture 5 - ATP synthesis: Oxidative phosphorylation and the electron transport chain Flashcards
what is ATP synthesis?
Oxidative phosphorylation – indirect way of producing ATP
Donates electrons – transported along the electron chain
when is substrate level phosphorylation important?
when we need energy rapidly w/o oxygen
when is NAD+ converted into NADH?
during high intensity exercise as energy demand is high in the cell
what does energy production via the ETC (electron transport chain) cycle rely on?
redox reactions - gaining electrons
where does this process occur?
inner mitochondrial membrane
how does the redox potential/electron affinity work?
goes through 4 complexes where Electron carries energy – more it carries the more binding it will undergo
Can still bind if it has less energy – can accept the enzyme more easily
Affinity increases across these 4 complexes and it starts to be accepted
what is complex 1 and 2?
first oxidation of NADH – NAD+ loses electrons which are accepted by complex 1
FADH donates their electrons to complex 2
what do the electrons do which are generated at the start of this chain?
move along the chain from complex to complex - this continues until complex 4 when the electrons are accepted by oxygen
- the hydrogen atoms are transported from inside the mitochondrial matrix
what is chemiosmosis?
the transfer of hydrogen atoms from the mitochondrial matrix to the intermembrane space
since there are little to no hydrogen atoms left how are the hydrogen atoms pumped back into the mitochondrial matrix?
by the ATP synthase
- Rota spins creating kinetic energy which is used and stored in the bonds between the phosphate groups and ADP to form ADP
what process results in the generation of ATP?
diffusion
how is the ETC regulated?
no allosteric control - depends on the energy status of the cell, ADP is a sign it has been used and needs to be recycled back into ATP so that energy can increase – energy status of the cell is low
Higher concs – cell tells us that we need more energy so the speed of the electron chain can increase – rate at which oxidation phosphylarte occurs can be reduced
generated in the TCA cycle, how many molecules of NADH generate of ATP molecules?
3
generated in the TCA cycle, how many molecules of FADH2 generate of ATP molecules?
2
if the process is efficient how many ATP molecules will be generated?
38 - wont be entirely efficient as some molecules will be pulled away from the krep cycle
why is the ETC not a major pathway for energy production during short duration, high intensity exercise?
its too slow and so relies on anaerobic exercise
what about fructose?
cant directly be metabolised, needs to be converted to glucose before we can use it – happens in the liver
