Electron transport chain and chemiosmosis

based on the notes from in class students

exergonic

cellular respiration is:

steps

When glucose is oxidized and energy is released in

cellular respiration, in order to do useful work, it

must be done in ____ rather than all at once.

oxidizing

Cellular respiration is the process of _____

glucose or stripping glucose of its electrons

gradually (in steps) and harnessing the energy

released for work. The ETC is the last of these

steps.

inner mitochondrial membrane

Final step of cellular respiration

In eukaryotes, it takes place in the:

cristae

___ increase the inner membrane’s

surface area; provides space for more

copies of the components of the ETC.

fall of electrons

The ETC doesn’t produce ATP itself; it eases

the ____ from glucose to oxygen,

while creating a H+ ion concentration to

power ATP synthesis (chemiosmosis)

oxidative phosphorylation

The ETC and chemiosmosis together make

up ________, which

produces ATP

input

ATP Synthesis requires an _____ of energy (endergonic)

intermediate

This energy can come directly from a high-energy phosphorylated

_______ or from an Electron Transport Chain

substrate level

___ phosphorylation: uses an enzyme to directly transfer a

phosphate group from a high- energy phosphorylated intermediate to

ADP

oxidative

___ phosphorylation: uses an electron transport chain and

chemiosmosis to create a proton gradient which powers ATP synthase

less to more

Electrons move from ________

electronegative carriers

free energy

As electrons move down the chain,

they move from a higher-energy to

lower-energy state and release ______ as they go

oxidized

Electron carriers are reduced and then

____ as electrons pass through

them

Protein complex I

a multi-protein complex

immobile/permanent

Protein complex I

Receives 2 electrons from NADH (becomes NAD+

and H+)

contains the prosthetic group FMN and an Fe-S

protein

Protein complex I

Acts as a proton pump when electrons pass

through it, pumping H+ ions from the

mitochondrial matrix to the intermembrane

space (active transport)

prosthetic group

a permanent non-protein, non-

amino acid group which helps enzymes catalyze

reactions

protein complex 2

immobile/permanent

Receives 2 electrons from FADH2 (becomes FAD

and H+)

protein complex 2

Only protein complex which does NOT pump

protons across the membrane due to

insufficient energy from FADH2

FADH2

Although they both donate 2 electrons, ______

donates less energy/makes less ATP than NADH

because the electrons are donated at a later

point in the chain, and therefore:

Enter at a lower energy state

Pass through/power fewer proton pumps

conenzyme q

also known as CoEnzyme Q

small lipid

Not residential in one protein complex; mobile

Collection point and shuttle for electrons from

Protein Complexes I and II, transports them to

Complex III

mobile

conezyme q is mobile or immobile?

immobile

*Cytochrome: electron carriers with a heme prosthetic

group (Fe atoms accept electrons). Usually _____;

however, Cyt C is the exception

protein complex 3

Receives only 2 electrons at a time from ubiquinone

Pumps H+ ions into inter-membrane space

Cytochrome C (the next carrier in the chain) can only

recieve 1 electron at a time

q cycle

splits up the 2 electrons so that 1

continues along the chain and the other is recycled

to form another ubiquinol (the oxidized form of

ubiquinone)

complex 3

___ transfers 2 electrons (one at a time) to

two separate cytochrome c molecules, which then

take 2 electrons to Complex IV

complex 4

Immobile/permanent

Receives 2 electrons (one at a time) from 2 Cyt C

molecules

Pumps H+ ions into inter-membrane space

complex 4

Electrons pass through cytochrome a and copper

centers to cytochrome a3 in ____

a3

Cytochrome _____ transfers electrons to oxygen, the

final electron acceptor

oxygen

__ requires 4 electrons and one H+ to become

water; therefore, electrons need to be transferred to

oxygen in multiple steps

chemiosmosis

allows for ATP synthesis

membrane

Protein Complexes I, III, and IV pump H+ ions across the _____ (into the

intermembrane space)

electrochemical

H+ pumping creates an ___ gradient

chemical gradient

caused by a difference in H+ concentration

electrical gradient

the intermembrane space becomes more positively charged, and

the matrix more negative; H+ ions are then attracted to the matrix

transport protein

The H+ ions want to diffuse down the electrochemical gradient (into the matrix), but

cannot pass the membrane without the help of a _____

proton motive force

As H+ ions are pumped to the intermembrane space, the energy from the

electrons is being converted into the potential energy of the proton

gradient - this is called the ______

synthase

This potential energy is harnessed by ATP _____ to synthesize ATP

ATP synthase

an enzyme (-ase) that catalyzes the reaction

forming ATP from ADP and an inorganic

phosphate molecule

ATP synthase

made of two main components: F0 and F1

F0

embedded in the membrane

stator

in F0:

the _____ provides a channel for protons to diffuse across the

membrane (following their electrochemical gradient)

rotor

in F0:

protons enter a ___, where they bind to specific sites and

change the shape at those sites; this causes the rotor to spin

f1

located in the matrix

f1

the rotor of F0 is connected to a rod/shaft which rotates within _____

this rotation causes the active sites of the ____ component to change

shape

shape change

this _____ allows ATP synthase to bind ADP and the

phosphate, create ATP, and then release the new molecule

in chemiosmosis

26-28

For each molecule of glucose, ATP synthase produces_____

ATP molecules.

NADH

creates about 25 ATP

FADH2

creates about 3 ATP

10

NADH+ created:

2

FAD created:

6

water created:

10 NADH, 2 FADH2, 6O2

inputs of ETC: