Electron Transport And Oxidative Phosphorylation Flashcards
(39 cards)
. ATP functions
. Perform mechanical work
. Transport molecules and ions across membranes
. Drives rxns that would be unfavorable by coupling rxn w/ hydrolysis of ATP
Sources of ATP
. Glycolysis (substrate level phosphorylation)
. ETC/oxidative phosphorylation
Most important pathways for tissues using aerobic energy
. TCA, ETC, oxidative phosphorylation
most catabolic pathways are associated w/ what location?
Mitochondria
Most molecules enter aerobic pathway as ___
Acetyl CoA
Oxidative phosphorylation
Process where ATP is formed from ADP and P as result of energy obtained from electron transport
Electron transport
. Transfer of electrons from NADH or FADH2 to O2 through series of electron carriers
Mitochondria in aerobic energy generation
. Outer membrane very permeable
. Inner membrane very impermeable and rich in membrane proteins
. Cristae: convolutions of inner membrane, which inc. surface area
. Contains many catabolic enzymes (TCA, fatty acid oxidation, amino acid degradation)
. ATP exits matrix, ADP enters matrix
Flow of NADH in ETC
NADH -> I -> Q -> III -> C -> IV -> O2 (total 10 protons pumped making 2.5 ATP)
Flow of FADH2 in ETC
FADH2 -> II -> Q -> III -> C -> IV -> O2 (6 protons pumped for 1.5 ATP)
Complex I in ETC
. NADH dehydrogenase
. Accepts reducing equivalents from NADH and passes them to CoQ
. Multiple H+ are pumped out as electrons pass through complex I
. Embedded in inner. Mitochondria Membrane
. Fe-S centers
. Electrons flow from NADH to FMN to FeS to CoQ
CoQ/Ubiquinone in ETC
. This is nonpolar, lipophilic carrier (not protein) which diffuses w/in the membrane
. Does NOT pump H
. Accepts reducing equivalents from either complex I or II and passses them to complex III
. Reversibly reduced and oxidized in ETC
Complex II in ETC
. Succincate dehydrogenase
. Also in TCA
. Reducing equivalents from this step in TCA pass their electrons directly onto the ETC here
. Embedded in inner mitochondria membrane
. Tightly bound FAD and FeS centers
. Electrons flor from succinctness to FAD to FeS to CoQ
. Accepts reducing equivalents from succinctness and passes them to CoQ
. Does NOT pump H
Cytochromes
. Contain iron in heme-like structure
Complex III in ETC
. Cytochrome bc1
. Contains 2 hemes, FeS groups, cytochromes b and c
. Multiple H ions pumped out as electrons pass through complex III
. Accepts reducing equivalents from ubiquinone and passes them to cytochrome c
Cytochrome c
. Heme-like group
. Water soluble protein loosely assoc. w/ membrane
. Released in apoptosis
. Accepts reducing equivalents from complex III and passes them to complex IV
. Does NOT pump H
Complex IV in ETC
. Cytochrome a+a3/ cytochrome oxidase
. Contains heme-like group
. Protein interacts w/ oxygen
. Multiple H+ pumped out as electrons pass through complex
. Cyanide and CO inhibit this step
. Tightly assoc. w/ inner membrane
. Accepts reducing equivalents from cyt. C passing them to O2 fo generate water
Result of ETC
. Proton gradient made across inner mitochondrial membrane
Chemiosmotic hypothesis
. ETC and ATP synthesis coupled by proton gradient across inner mitochondrial membrane (High H+ outside matrix)
. Proton-motive force drives ATP synthesis
. Change in pH about 1 across inner membrane
Complex V in oxidative phosphorylation
. ATP synthase
. 2 parts
. ETC generates proton gradient used to power conversion of ADP and P to ATP and mechanical rotation of F1 subunit
T/F ETC and oxidative phosphorylation are coupled
T, one can’t happened w/o the other
Natural uncoupling of EC and oxidative phosphorylation
. ETC produces heat instead of ATP
. Occurs in brown fat
White adipose
. 50% cutaneous, 50% around organs
. Unilocular
. Large cytoplasmic drops of triglycerides w/ few organelles
Brown adipose
. Expresses UCP-1
. Generates heat
. Most prominent in infants in neck, upper chest, and upper back
. Multilocular
. Many small cytoplasmic drops of triacylglycerol, many mitochondria, more vascularized
