unit 12: oxidative phsophorylation

oxidative phosphorylation

the process in which ATP is formed as electrons are transferred from NADH or FADH2 to O2 by a series of electron carriers

inner mitochondrial membrane

where does oxidative phosphorylation occur?

impermeable

-access is only gained via a variety of transporters within the mitochondrial membrane

the inner mitochondrial membrane is very BLANK

dehydrogenase enzyme

what enzyme completes oxidative phosphorylation of NAD+ to NADH and FAD to FADH2?

1. direct transfer

2. transfer as a hydrogen atom

3. transfer as a hydride ion

electrons from NADH and FADH2 pass through membrane-bound carriers in one of three processes:

cytochromes

ubiquinone

iron-sulfur proteins

3 types of electron carriers:

ubiquinone (coenzyme Q or Q)

an electron carrier that can carry 2 electrons at a time

cytochromes

proteins that contain porphyrin rings bound to a central iron atom that can change oxidation states

-carries

iron-sulfur proteins

contain a cound iron atom that can change oxidation states, the iron is co-ordinated by multiple sulfhydryl groups

multi enzyme complexes

electron carriers of the respiratory chain

-hydride moved from NADH to ubiquinone

-4 protons are pumped across the inner membrane

Complex 1: NADH: ubiquinone oxidoreductase (or NADH dehydrogenase)

-succinate dehydrogenase is the ONLY membrane enzyme in CAC

-no protons are pumped across the membrane

complex 2: succinate to ubiquinone

no only 1 is used at a time

will both complex one and complex two be used together?

4 less protons get pumped across the membrane

if you start with complex 2 (start with FADH2) then,...

-one iron for every cytochromic

-electrons from ubiquinine are transferred to cytochrom c which reduces the iron atom

complex 3: ubiquinone: cytochrome c oxidoreductase

-electrons from cytochrome c are transferred to oxygen

complex 4: cytochrome oxidase

NADH + 11 protons (-) + 1/2 H2O = NAD+ + H2O + 10 protons (+)

overall transfer of electrons from NADH to O2:

Complex 1 is skipped, therefore only 6 H+ are pumped across the membrane

what is the major difference when the electrons come from FADH2?

proto-motive force

-inward flow of 3 H+

the synthesis of ATP is driven by...

ATP synthase

what enzyme is used to synthesize ATP?

F0 and F1

2 distinct domains of ATP synthase:

F0

a hydrophobic segment that spans the inner mitochondrial membrane and contains the protein channel for the complex

F1

protrudes into the mitochondrial matrix and contains the catalytic activity of the enzyme

1. newly released ATP, binding site is empty and waiting for substrates

2. a tightly bound ADP + Pi are waiting to be coupled

3. a newly synthesized ATP waiting for release

F1 subunits have 3 non-identical alpha/beta binding sites. each site has either:

inward movement of 3 H+

the BLANK back into the matrix triggers the next step at all three subunits of ATP synthase

-2 translocase enzymes

-phosphate source

-movement of an additional proton

what is required for ATP to exit the mitochondria?

the relatively low proton conc'n in the matrix favors the inward movement of an additional H+ (leaks in)

why is an extra proton needed for ATP to exit the mirochondria?

antiporter

2 compounds moving in opposite directions

symporter

2 compounds moving in same direction

inward movement of 3H+

in oxidative phosphorylation, the formation of 1 ATP molecule requires:

inward movement of 1 additional H+

in oxidative phosphorylation, the movement of ATP to the cytosol requires:

2.5 ATP

- 10 H+ in electromotive phase

- 4 H+/ATP in protomotive phase

in oxidative phosphorylation, each electron pair carried by NADH produces:

1.5 ATP

-pumps out 4 less protons

in oxidative phosphorylation, each electron pair carried by FADH2 produces:

shuttle systems

BLANK are required to move cytosolic NADH into the mitochondria

glycerol 3-phosphate shuttle

what shuttle system does skeletal muscle and the brain use?

-delivers electrons of NADH to ubiquinone through FAD

-bad currency exchange

-2 NADH enter and are converted to FADH2 and enter at complex 2

glycerol 3-phosphate shuttle:

32 ATP

if 2 NADH are able to enter at complex 1 then how many ATP molecules can be formed from a moelcule of glucose?

30 ATP

-8 protons are NOT pumped across membrane

-cell loses ability to make 2 ATP since 4 protones are required to synthesize/release ATP

if 2 NADH use the shuttle and enter at complex 2 how many ATP molecules can be formed from a molecule of glucose?

malate-aspartate shuttle

what shuttle system functions in the liver, kidney, and heart?

NADH is moved into the mitochondria as NADH

why is the malate-aspartate shuttle better?

two reversible reactions

the malate-aspartate shuttle is based on...

-oxaloacetate to malate

-NADH oxidized to NAD+

-dehydrogenase enzyme

what is reaction 1 of the malate-aspartate shuttle?

aminotransferase or transamination (transfers an amine)

-oxaloacetate to aspartate (keto acid to amino acid)

-glutamate to a-ketoglutarate (amino acid to keto acid)

what is reaction 2 of the malate-aspartate shuttle?

increased

when the concentration of substrate is increased, oxidative phosphorylation is...

acetyl coA

citrate

succinyl coA

what are the 3 product feedbacks in citric acid cycle?