Electron Transport and Oxidative Phosph

Complex I

NADH dehydrogenase

Complex I (NADH dehydrogenase)

Accepts electrons from NADH and pumps H⁺ into the intermembrane space.

complex II

succinate dehydorgenase

Complex II (Succinate dehydrogenase

: Accepts electrons from FADH₂ but does not pump H⁺.

Complex III (Cytochrome bc₁ complex)

Transfers electrons to cytochrome c and pumps H⁺.

Complex IV (Cytochrome c oxidase)

Transfers electrons to O₂ (forming H₂O) and pumps H⁺.

Complex III

Cytochrome bc₁ complex

Cytochrome c oxidase

complex IV

electrons flow into the ETC via

electron carriers

the electron carriers in the ETC are

NADH and FADH2

NADH is the electron carrier for

complex 1

FADH2 is the ecltron carrier for

complex 2

electrons flow from complex 1 and 2 to

conenzyme Q (ubiquinone)

Electrons flow from ubiqiouine to

complex III

complex iii hands electrons to

cytochrome C

cytochrome c hands electrons off to

complex IV which passes them to final electron acceptor 02

Energy released during electron transfer pumps H⁺ from the matrix to the intermembrane space at

Complexes I, III, and IV.

energy released during electron transfer makes a

proton gradient

Substrate-level phosphorylation

ATP is made by direct transfer of a phosphate from a substrate to ADP (occurs in glycolysis and the TCA cycle).

Oxidative phosphorylation

ATP is made using the proton gradient generated by the ETC, with ATP synthase producing ATP.

F₀F₁-ATPase (ATP Synthase) allows H+ to

 flow back into the mitochondrial matrix.

ATP Synthases uses the energy from

proton movement to convert ADP + Pi → ATP.

When ADP and Pi are abundant

there is high energy demand and ATP is produced

atp synthesis requires oxygen as the

final electron acceptor, without O2 atp production stops

ADP

stimulates ATP synthesis

when NADH/FADH2 are high

more atp is produced

inorganic phosphate (Pi) is

required for ATP formation

Concentration gradient (ΔpH)

Difference in H⁺ concentration across the membrane.

Electrical gradient (Δψ)

Difference in electrical charge across the membrane.

proton motive force (PMF)

provides the energy to drive ATP synthesis.

large proton gradient

more energy avaiaible for atp production