Choose a site along the electron transport chain out of the following that is not coupled to ATP synthesis.
Choose a site along the electron transport chain out of the following that is not coupled to ATP synthesis.
The correct option is B Complex II
An electron transport chain (ETC) is a series of complexes that transfer electrons from a donors to a acceptors via redox reactions.
Coupled to this electron transfer is the transfer of protons across a membrane, which creates an electrochemical gradient that drives the synthesis of ATP.
In mitochondria, electron transfer occurs through complexes I to IV on the inner membrane of the organelle.
Complex I is composed of flavin mononucleotide (FMN) and an enzyme containing iron-sulfur. It receives electrons from NADH2 and pump four protons across the membrane.
Complex II receives electrons only from FADH2 and passes it on to ubiquinone.This complex is not coupled to a proton pump.
The third complex called cytochrome oxidoreductase receives electrons from ubiquinone and passes it on to cytochrome C.
Complex IV receives the electron from cytochrome C and reduces oxygen to water.
Both Complex III and complex IV are coupled to proton pumps that help creates the electrochemical gradient necessary for ATP synthesis.
As complex II is not coupled to a proton pump, ATP synthesis does not take place at this stage.
Complex II
An electron transport chain (ETC) is a series of complexes that transfer electrons from a donors to a acceptors via redox reactions.
Coupled to this electron transfer is the transfer of protons across a membrane, which creates an electrochemical gradient that drives the synthesis of ATP.
In mitochondria, electron transfer occurs through complexes I to IV on the inner membrane of the organelle.
Complex I is composed of flavin mononucleotide (FMN) and an enzyme containing iron-sulfur. It receives electrons from NADH2 and pump four protons across the membrane.
Complex II receives electrons only from FADH2 and passes it on to ubiquinone.This complex is not coupled to a proton pump.
The third complex called cytochrome oxidoreductase receives electrons from ubiquinone and passes it on to cytochrome C.
Complex IV receives the electron from cytochrome C and reduces oxygen to water.
Both Complex III and complex IV are coupled to proton pumps that help creates the electrochemical gradient necessary for ATP synthesis.
As complex II is not coupled to a proton pump, ATP synthesis does not take place at this stage.
