Metabolism Flashcards
Energetic efficiency definition
Ratio of protons translocated for every electrion/oxygen molecule
o2 pulse technique
Right side vesicles produced from bacteria to measure efficiency of certain part of transport chain
Known volume of o2 added
Measure pH produced - can work out ratio
Right side out vesicle
Vesicle produced from bacterial inner membrane
Lacks cell wall and outer membrane
Trap chemicals inside e.g. NADH
Anaplerotic reaction
Anaplerotic reactions are biochemical processes that replenish the intermediates of the citric acid cycle (also known as the Krebs cycle or TCA cycle). These reactions help to maintain the cycle’s activity and ensure the availability of energy substrates for cellular processes.
Paracoccus denitrificans
Ubiquinol
Ubiquinol, is the reduced form of coenzyme Q10.
CoQH2
Ubiquinone
Quinone + hydorphobic tail
The oxidized form of coenzyme Q10.
Complex 1
NADH dehydrogenase + FMN + Fe-S
4H+ passed through
Electrons released from oxidation of NADH
Complex 2
Succinate dehydrogenase + FAD + Fe-S
No H+ pumped through
Succinate oxidised to Fumarate
Alternative pathway into ETC
Cytochrome
A cytochrome is a protein involved in electron transfer that contains a heme group.
Standard reduction potential
Standard reduction potential measures the tendency for a given chemical species to be reduced
How does e-coli respond to changes in oxygen levels?
Change cytochrome composition i.e. ETC composition
E.coli response in high o2
Cytochrome bo3 oxidase
Arc Regulon
Anoxic Redox Control system
Arc system is a two-component system found in some bacteria that regulates gene expression in faculatative anaerobes such as Escheria coli.
ArcA and ArcB
Two-component system
System consisting of a sensor molecule and a response regulator.
ArcA
DNA binding protein
Response regulator
Represses aerobic genes
Activates cyd genes e.g. cyt bd oxidase
ArcB
Membrane bound histidine kinase
Senses QH2 levels -> higher = lower oxygen due to electrons not being passed on
Fnr system
fumarate and nitrate reductase
Switches from aerobic to anaerobic respiration if oxygen or nitrate unavailable
What operon does arc system control?
sdh operon encoding succinate dehydrogenase
ArcB inactivation
Quinones oxidise cys180 residues in ArcB
Disulphide bonds form = changes ArcB conformation
2 disulphide bonds = complete silencing of kinase activity
Succinate dehydrogenase
Complex 2 in ETC
Repressed in anaerobic conditions
MK
Menaquinone
