Electron Transport Chain

The electron transport chain

The electron transport chain is located on the inner mitochondrial membranes. The chains use energy from electrons to pump H+ ions into the intermembrane space. A proton gradient is established which enables chemiosmosis to occur through ATP synthasae. The sequence of events is as follows:

Most of the ATP generated  in respiration is produced via oxidative phosphorylation. The reduced coenzymes  FADH2 and NADH produced during the earlier stages of respiration such as glycolysis donate H+ ions and electrons to an electron transport chain and ATP is synthesised.

There are 5 complex called :

Complex 1-NADH Dehydrogenase

Complex 2-Succinate Dehydrogenase

Complex 3-Cytochrome C reudctase

Complex 4-Cytochrome C oxidase (a-a3 Complex)

Complex 5-F0-F1

Mobile carriers:

Q= Ubiquinone

Cyt C=Cytochrome C 

Let's talk about NADH the first product made from  glycolysis. It transfers h+ and E- electrons into Complex 1 to Q a mobile carrier and then to complex 3 to Cyt C another mobile carrier to complex 4 where the electron is accepted by oxygen with hydrogen to make water. All this movement from the electron carriers complexes have created energy this energy is used to pump hydrogen ions into the intermembrane space which create a proton gradient this then means that H+ ions can enter back into the matrix this is done by complex 5 and this then causes ADP to hydrolysis with Phosphate to create ATP.

For every 2H+ion 1 ATP is created

altogether the 6 H+ ions creates 3 ATP

Now let's talk about the second product used from glycolysis called FADH2, it takes a slightly different pathway. FADH2 is oxidised to FAD+ in complex 2 and enter Q mobile carrier where electrons travel to complex 3 and then to Cyt C mobile carrier and then to complex 4 where electrons get accepted to oxygen and hydrogen to produce water, H+ ions pump from complex 3 and complex 4 and this creates a proton gradient where H+ ions enter back via complex 5 which creates ATP.

-4H+ ions can produce 2 ATP

Overall this how much energy is created from oxidative phospohorylation:

	ATP	NADH/FADH2	ECT ATP produced
Glycolysis	4	2 NADH	6
Link Reaction	------	2 NADH	6
TCA Cycle	2	6 NADH 2 FADH	18 4
Total:	6		34

Total: 6+34=40 ATP

*Net gain ATP: 40-2=38

*Hint: 2 ATP was used in the beginning of glycolysis.*

**REMEMBER TO STAY POSITIVE LIKE A PROTON**