oxidative phosphorylation

What is the oxidation part of ox phos?

reduced electron carriers (NADH, FADH2) are re-oxidized and the electrons are passed to O2, generating H2O

What is the phosphorylation part of ox phos?

some of the free energy released during the oxidation is harnessed to drive the phosphorylation of ADP, making ATP

Where does ox phos occur?

inner mitochondrial membrane

Is the inner mitochondrial membrane permeable?

no

Which membrane has many porins?

outer mitochondrial membrane

Is ATP synthase a part of the ETC?

no

What pH levels does ox phos cause?

pumps protons out, so high pH in mitochondrial matrix

What are the components of the ETC?

coenzyme Q, complex I-IV, cytochrome c

What is cytochrome c?

peripheral membrane protein

What prosthetic groups /cofactors are involved in the ETC?

Fe-S clusters, Cu2+, cytochrome heme groups, FMN/FAD

What cosubstrate is involved in the ETC?

coenzyme Q

What are iron-sulfur clusters?

-prosthetic group
-can only carry one electron at a time
-no hydrogen involved
-Fe3+ + e -> Fe2+

What is cytochromes?

-hemoproteins that carry out electron transport
-Fe3+ + e -> Fe2+

Is hemoglobin a cytochrome?

no, because Fe2+ is never oxidized

In what forms can FAD accept electrons?

2H+ + 2e-
one H
two H

What is the first prosthetic group of complex II?

FAD

In what forms can FMN accept electrons?

2H+ + 2e-
one H
two H

What is the first prosthetic group of complex I?

FMN

What makes coenzyme Q membrane soluble?

50 carbon tail

What is the most flexible electron carrier?

coenzyme Q

In what forms can Q accept electrons?

one H
two H

Electrons move __ through the electron chain via a series of linked reactions.

spontaneously; redox

Electrons move from molecules with reduction potential to molecules with a _ reduction potential.

lower; higher

has the highest reduction potential.

O2

What is the path of electrons from NADH through the ETC?

enter via complex 1 (4 H+ pumped). Q is reduced to QH2, passes the electrons to complex III (4 H+ pumped). 2 Cyt c pass electrons to complex IV (2 H+ pumped). electrons passed to O2

How does complex I process electrons?

contains FMN, which receives electrons from NADG, and passes them to FeS clusters

What is unique about FMN as an electron carrier?

it can accept or give away one or two electrons at a time

Q has a ___ reduction potential than complex I and II.

higher

What does a large + ΔE°' correspond to?

a large - ΔG°'

Each NADH is association with the pumping of protons across the , from the _ to the ____.

10; inner mitochondrial membrane; matrix; intermembrane space

What is the proton electrochemical gradient?

pumping of H+ across membrane causes the matrix to have high pH (low [H+]) and inter membrane space to have low pH (high [H+])

Electron transport causes a which allows complexes to pump H+ ions.

conformational change

Movement of electrons through the ETC is linked to movement of across the ___.

H+; inner mitochondrial membrane

Can you move electrons if you are not able to pump protons?

no

Approximately are needed per ATP synthesized via ATP synthase?

3H+

Where is the catalytic domain of ATP synthase located?

in matrix

What is the Fₒ ATP synthase domain?

-transmembrane portion
-protons pass through
-triggers conformational change in F₁

What is the F₁ ATP synthase domain?

-catalytic portion
-synthesis of ATP from ADP and Pi

The _ of the H+ gradient is converted to and then to ___ in the phosphoanhydride bonds of ATP.

potential energy; mechanical energy; chemical energy

What determines the rate of oxygen consumption?

speed of electron transport

What is the path of electrons from FADH2?

enter via complex II. Q is reduced to QH2, passes the electrons to complex III (4 H+ pumped). 2 Cyt c pass electrons to complex IV (2 H+ pumped). electrons passed to O2

Why can electrons never go backwards in the ETC?

complex II has a higher reduction potential than complex I

Can FAD ever move from complex II?

no, it is a prosthetic group

Why are 2 cyt c required?

only have one heme group that can carry one electron, but two electrons are donated per NADH or FADH2

What is complex II also called?

succinate dehydrogenase

How does complex II take part in the CAC and ETC?

oxidizes C-C bond in succinate to C=C bond in fumarate, then passes electrons to FAD to be reduced to FADH2, then passed to Fe-S and Q

Where do most electrons in the ETC come from?

NADH

Why does complex II not pump any protons?

it does not generate enough energy

Each FADH2 is associated with the pumping of protons across the IMM.

6

What is the reaction that ATP synthase catalyzes?

H+ + ADP + Pi -> ATP + H2O

_ creates H+ gradient, uses H+ gradient

oxidation; phosphorylation

What is the adenine nucleotide translocase?

-antiporter in IMM
-ATP produced in matrix is sent to inter membrane space, ADP is brought into matrix

What is the Pi H+ symporter?

moves Pi and H+ across IMM into matrix

The rates of electron transport and of oxygen consumption are coupled to the rate of ATP synthesis through the of the H+ electrochemical gradient.

magnitude

A large H+ gradient ___ electron transport.

slows down

What occurs when there is a low concentration of ADP in the matrix?

decrease ATP synthase activity -> increased H+ gradient across IMM -> decreased rate of electron transport/O2 consumption -> decreased oxidation of NADH and FADH2 -> increased concentrations of NADH and FADH2

What occurs when there is a high concentration of ADP in the matrix?

increased ATP synthase activity -> decreased H+ gradient across IMM -> increased rate of electron transport/O2 consumption -> increased oxidation of NADH and FADH2 -> decreased concentrations of NADH and FADH2

What is the Fo portion of ATP synthase?

-transmembrane portion
-protons pass through
-triggers conformational change in F1

What is the F1 portion of ATP synthase?

-catalytic portion
-synthesis of ATP from ADP and Pi

It is the __ that determines proton movement and ultimately oxygen consumption.

rate of ATP synthesis

The P/O ratio relates the number of synthesized to the amount of ___ consumed.

ATP; oxygen

What is the P/O ratio for NADH?

-2.5
-2 electrons from NADH generates a H+ gradient of 10
-4 H+ needed for each ATP synthesis (3 via ATP synthase and 1 via the phosphate symporter)

What is the P/O ratio for succinate (FADH2)?

-1.5
-2 electrons from FADH2 generates a H+ gradient of 6
-4 H+ needed for each ATP synthesis (3 via ATP synthase and 2 via the phosphate symporter)

mitochondria in brown fat produces __.

uncoupled; heat

What do uncoupling proteins do?

create proton leak on the inner mitochondrial membrane; uncoupling the proton gradient without ATP synthesis

Why will animals purposely uncouple oxidative phosphorylation?

need brown adipose tissue to generate heat

Does white fat or brown fat have more mitochondria?

brown fat

Why does uncoupling oxy phos produce heat?

the potential energy stored in the gradient has to be released somehow, so it is released as heat

How does 2,4-dintrophenol work?

-dissapates proton electrochemical gradient
-tricks the body into thinking there is no ATP, so breaks down stores to create ATP
-leads to heat generation and dehydration