The elctron tansport chain; the hydrogen atoms carried by reduced NAD+FAD
molecules generated in the krebs cycle are the source of electrons that are
passed along a series of electron carriers which form the elctron transport chain
Reduced NAD or FAD from Krebs
H+
2e-
2e-
H2O
2H+
1/2 O2
Electrons at
low energy level
Electrons at high
energy levels
The site of the electron transport chains and AP production; the redox reactions
take place on the inner memebranes of mitrochondria in which the electron
carriers are embedded. The inner membrane is highly folded into structures
called cistrae which increase the surface area on which the reations take place
According to the chemisomotic theory each individual
redox reaction releases energy, but not enough to make
ATP. Instead, the energy is used to pump protons (H+)
from the mitrochondrial matrix into a compartment
between the inner and outer mitrochondrial membranes
The protons accumilate so that a steep concentraion gradient
develops between the compartment and the mitochondrial
matrix. The inner membrane is generally impermeable to the
protons except at special structures called stalked particles
which function as chemiosmotic channels. Therefore, the
protons can only diffuse back into the matrix through the stalked
particles. The energy associated with the flood of protons
through the chemiosmotic channels drives the synthesis of ATP.
The photophorylation of ADP is catalysed by an enzyme called
ATPase loacted in the bulbous end of the stalked particle