L9 Respiration and chemiosmosis hypothesis Flashcards
What is it called when bacteria like E.coli use nitrate to respire
dissimilatory nitrate reduction
what happens when we drink nitrate in water
bacteria in gut convert nitrate into nitrate which can oxidise our blood
under anaerobic conditions what does pyruvate get transformed into
formate
where do the electrons that are required to reduce nitrate come from
formate dehydrogenase (membrane-bound protein) reduces formate which produces CO2 and H+ and electrons
what is the oxidative complex within the nitrate reductase complex loop
formate dehydrogenase
where do the electrons from the reduction reaction of formate go
move down formate dehydrogenase to menaquinone
what does menaquinone do
takes the two electrons from formate reduction and 2 protons from cytoplasm to become menaquinol
what happens to the menaquinol
gets oxidised back to menaquinone passing the electrons to nitrate reductase and the protons go into the periplasm
what are the electrons that are passed to nitrate reductase used for
reduce nitrate into nitrite
how do bacteria generate a proton motor force during anaerobic respiration
using a redox loop
formate dehydrogenase and nitrate reductase are an example
what is the proton motor force
electrochemical gradient
what is a proton motor force used for
drive endothermic reactions in the cell
ATP synthase/lac permease
why is succinate dehydrogenase a unique enzyme
part of Kreb cycle and electron transport chain
who is sir peter Mitchell
pioneer of the chemiosmotic hypothesis
how did sir peter Mitchell prove his hypothesis? 2 experiments
fed succinate to intact cells then
- measured how much ATP is produced
- measured oxygen consumption
fed succinate to cells that had been broken with a sonicator
- measured ATP
- measure oxygen consumption
what happened to the succinate when Peter fed it to an intact cell
gets translocated by the major facilitator superfamily and then gets oxidised to fumarate in the Krebs cycle.
-because it is oxidised in the membrane it can create a proton motor force
why was it so important that peter Mitchell used succinate (a non-fermentable carbon source) as a substrate instead of glucose or alpha-ketoglutarate
succinate cannot be used to produce ATP whereas glucose can undergo glycolysis which produces ATP
-alpha-ketoglutarate can produce GTP which can be converted to ATP
what happened when Mitchell fed succinate to broken cells
- oxygen was still consumed because succinate diffused into the cell and was oxidised to fumarate
- ATP was not produced because no proton motor force could be formed with a broken membrane
what is the pH difference between the inside and outside of cells
- 5 outside
7. 5 inside
when the protons are translocated across the membrane what two gradients occur
pH gradient (Z delta pH)/ chemical gradient electrical gradient/membrane potential (delta sigh)
what is meant by an electrical gradient
the H+ on the outside of the cell makes the outside positive and the inside negative
