Mitochondria and Oxidative Phosphorylation Flashcards Preview

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Flashcards in Mitochondria and Oxidative Phosphorylation Deck (28):


lipid unique to the mitochondrial inner membrane


mitochondrial myopathy

abnormal mitochondria with a disorganizedappearance and crystal structures within


voltate-dependent anion channels (VDACs

large non-selective pores on the outer membrane that allow meovement of anions such as phosphate, chloride, pyruvate, citrate, and adenine nucleotides

beta barrel structure hints a bacterial origins of mitochondria


mitochondrial genes

mitochondria contain their own DNA and tRNAs

proteins need to bew synthesized in the cytoplasm and then transported into mitochondria

only 13 subunits of the ETC are expressed in the mitochondrial genome


import of proteins into the mitochondrion

must have amphipathic

recognized by protein complexes TOM and TIM (transport outer and transport inner membrane

proteins transported as a linear peptide


oxidative phosphorylation

the process of using the energy from the electrochemical potential gradient generated by oxidation in the ETC to create ATP from ADP


Describe the electron flow through the ETC.

oxygen is the best electron receptor and has the largest positive reduction potential

more energy is released from the oxidation of NADH by O2 than the oxidation of FADH2 by O2 because NADH has a more negative reduction potential than FADH2


Complex I

accepts a free proton plus the hydride ion carried by NADH, has an Fe-S center


Complex II

does not span the membrane, contains succinate dehydrogenase

takes electrons from FADH2 and passes it onto CoQ


Coenzyme Q or ubiquinone

mobile carrier that accepts electrons from complexes I and II and donates them to complex III

linked to a 50 carbon lipid that allows it to diffuse through the membrane


complex III

cytochrome proteins have bound heme with an iron atom

electrons are transfered to cytochrome c


Complex IV

cytochrome c oxidase

complex passes electrons from cytochrome c to final electron acceptor O2


heme a, b, and c

heme a - long isoprenoid tail that can bind to proteins

heme b - more loosely bound

heme c - covalently attached to alpha helices

iron int he middle important for electron transport because can be oxidized from ferric to ferrous state and back


ATP synthase

a protein that acts like a motor to add phosphates onto ADP to make ATP, uses the proton motive force

couples energy of proton movement with conformational changes to carry out the reaction


adenine nucleotide translocase (ANT)

exchanges ATP and ADP in a 1:1 exchange


Name the five major mitochondrial inner membrant transporters.

ATP-ADP translocase, dicarboxylate carrier, tricarboxylate carrier, pyruvate carrier, phosphate carrier


What are the two methods of transporting electrons into the mitochondria?

glycerol 3-phosphate shuttle and malate-aspartate shuttle


Describe the glycerol 3-phosphate shuttle.

major shuttle in most tissues


Describe the malate-aspartate shuttle

cytosolic NADH is necessary for shuttle function


Describe the creatine phosphate shuttle.

muscle needs high ATP, needs a way to keep cytosolic ATP low but also store energy for action

prevents ATP from being used up by other processes


mitochondrial permeability transition pore

mitochondria become more permeable to small molecules, leads to mitochondrial swelling and cell death through apoptosis or necrosis


uncoupling proteins (UCP)

found in the inner mitochondrial membrane, creating a proton leak without generation of ATP

energy is released as heat, up to 20% of adult resting metabolic rate is due to energy expended to restore proton gradients lost to UCPs

babies have brown fat that have UCPs to generate heat



compound that can uncouple OXPHOS because it transfers protons across the inner membrane down their concentration gradient


How do the following inhibitors affect the ETC? - cyanide, carbon monoxide, hydrogen sulfide, and sodium azide

bind to the iron in the heme of the cytochrome aa3 component of cytochrome oxidase, preventing electron transfer to O2


How does antimycin affect the ETC?

it binds to cytochrome c reductase in complex II, inhibiting the oxidation of CoQ in the electron transport chain of oxidative phosphorylation


Howe do barbituates such as Amytal and Rotenone affect the ETC?

inhibit the transfer of electrons from iron-sulfur centers in Complex I to CoQ


How does atractyloside affect the ETC?

inhibits the ADP-ATP transporter in the inner membrane


How does oligomycin affect the ETC?