oxidative phosphorylation

oxidative phosphorylation

the process through which ATP is synthesized by the respiratory apparatus

what is used to generate ATP

reduced NADH and FADH2

around how much ATP is made in both NADH and FADH2

NADH: 2.5 ATP (round to 3)

FADH2: 1.5 ATP (round to 2)

where does oxidative phosphorylation occur

located on the inner membrane of the mitochondria

relationship between TCA cycle and electron transport chain

electron transport chain (ETC) has direct access to products produced by the TCA cycle

TCA cycle produces products in the mitochondria where they are directly used by the ETC

the electrons lost by NADH or FADH2 go where

they are transferred to coenzyme Q then to complex III then to cytochrome c then to complex IV then to O2 to generate H2O

oxidation

loss of electrons (losing an H)

ex: NADH ——> NAD+

FADH2 ———> FAD+

paired with reduction ——> redox reaction

reduction

gain of electrons (gaining an H)

ex: NAD+ ———> NADH

FAD ———> FADH2

paired with oxidation ——> redox reaction

how is oxidative phosphorylation a redox reaction

oxidation: NADH to NAD+, FADH2 to FAD+

reduction: O2 to H2O

cytochrome c

contains a heme and Fe atom which alternates between its reduced form Fe2+ and oxidized form Fe3+

catalyzes the reduction of molecular oxygen

takes the proton from complex III and passes it to complex IV

initial donor

NADH and FADH2

final acceptor

O2

relationship between electron transfer and free energy

transfer of electrons is accompanied by changes in the free energy of the system

loss of energy is used to pump out the proton across the membrane (creates a gradient)

where does the energy go in ETC

in the proton gradient and into the oxygen

is the intramembrane space high or low in concentration of protons

high

is the matrix of the mitochondria high or low in concentration of protons

low

ATP synthase

enzyme that synthesizes ATP

the energy in the proton gradient is used to power ATP synthase

the protons coming down their gradient causes the enzyme to rotate, during this ADP is tuned into ATP

how much ATP is produced in per 1 molecule of glucose in total

36 (or 38)

% efficiency

(amount of energy harvested/amount of energy available) x 100

list the steps of ETC

• NADH or FADH2 is oxidized which released releases a proton into the matrix

• coenzyme Q takes the proton formed by NADH or FADH2 and gives it to complex III

• cytochrome c takes the proton from complex III and gives it to complex IV

• the protons from complex IV is given to oxygen to make water

• the energy created during oxidizing NADH and FADH2 pumps protons across the membrane into the intramembrane space (pumped against concentration gradient)

• this makes sure that there would be a proton gradient that will be used for ATP synthase

• the proton gradient comes through ATP synthase. The energy from the proton going down its gradient, spins ATP synthase. ATP is then produced by the ATP synthase.