L6 energ prod from carb 3

Question 1

LO1: expl key role PDH in gluc metab.

Answer 1

-pyruv to aCoa for TCA. forms NADH and co2. in mito ma. 5 enx complex req FAD, thiamine, pryroP, lipoic ac cofacs. vit B1. irrev key reg step. PDH defic= lactic acidosis pyruv build up through LDH.
-PDH activ by pyruv, coASH, NAD+, adp, insulin deP.
inhib by aCoa, NADH, atp, citrate. Plat.

Question 2

LO2: desc roles of TCA cyc in metab.

Answer 2

• mito. acetyl to 2co2. oxidative reqs FAD and NAD. prod some energ GTP S lev P. prods precurs for bios eg haem, fa, aa, gluc. intermeds rem for bios req repl- maj from pyruv carboxylase pyruv to oxaloac, some from breakd aa. 2 cyc for ev gluc. all RP trapped.
• prods 6NADH, 2FAD2H, 2GTP.
• cent path in catab sug, fa, ketone bods, aa, alc. strat-prod molecs eas lose co2 to prod interconv c4 ac. main func breakd acet c-c form co2 by oxid. prods RP. prods GTP. prods precurs. req O for ETC use of FAD2H and NADH. intermeds act catal, no net synth/deg TCA alone.

Question 3

LO3: expl how TCA reg.

Answer 3

-energ avail. 2 irrev steps.
isocitrate DH activ by adp, inhib by atp, nadh.
alpha KG DH, inhib by atp, NADH and succin coa.

Question 4

LO4: desc key feats ox phos.

Answer 4

-mito. ETC and atp synth. NADH and FAD2H re oxid. O2 req reduced to H2O, pick up e- from reduced carriers. lot atp prod from bond energ.
-uses of RP in atp synth:
carrier e- transf through carriers to O. rel energ in steps, contr and effic.
free energ rel used to drive atp synth, ox phos.

Question 5

LO5: expl procs of e- transp and atp synth and how coupled.

Answer 5

• mito OM leaky. inner imperm to H+.
  each proton transloc complex unique set prots eg flavop, iron-S prots, cytochromes.
  in ma e- passed from carriers through complexes, gives up energ, pushes 2H+ out ma into intermem sp. 6H+ per NADH. FADH2 lower energ yield than NADH so feeds in mid, get 4H+ out. e- prov bond energ to form h2O from O. 30% energ used to transloc H+. lot rel as heat. H+ grad =pmf. elec chem grad.
• proton transloc atpase- uses atp to pump H+ out mito ma to cytop. can be rev to use pmf to form atp.
  -e- in NADH more chem bind energ than FADH2 more pmf. so NADH uses 3PTCs, FADH2 2. NADH 35% capt, FADH2 31%. rest gen heat.
  oxid 2 moles NADH= 5 moles ATP per O (P/O=2.5)
  oxid 2 moles FADH2= 3 moles atp (P/O=1.5).
  -regul- low adp means no S for atpase, stops inw flow H+ so H+ incr in intermem sp. prev H+ pump stops ETC. energ in e- insuff to pump H+ out into grad. rev with low atp.
  -inhibitors- block e- transp eg CN- prevs acc of e- by O. CO and CN bind head on high affin. block O interac termin carr, ETC back up, decr pmf. irrev.

Question 5

LO6: desc how when why uncoup occs in some tiss.

Answer 5

-uncouplers eg dinitrophenol, dinitrocresol, FA. incr perm IM to H+, dissip pmf. ET contins! lot heat gen.
-ox phos dis- genet defec prots encod by mtDNA (some su of PTCs and ATP synthase).
-brown adip deg coup contr by FA, extra heat gen.
conts thermogenin/UCP1. stress resp to cold= noradren rel SNS activs- lipase rels FA from TAG fuel for oxid. beta oxid makes NADH and FADH2 ent ETC incr pmf. UCP1 activ transp H+ back in mito. pmf energ rel as heat. neonate lot. UCP2 wide distrib pss link T2DM, obes, metab synd, heart fail. UCP3 skel musc, brown adip and heart modif FA metab and protec ROS dam.

Question 6

LO7: comp ox phos to S lev P.

Answer 6

• OXID- req mem assoc complexes. energ coup indirec by gen and util pmf. not occ w/o O, need it to pick up e-. maj ATP synth in cells req lot energ.
• S lev- req sol enzs cytop and ma. direc coup by form high energ hydrol bonds (P transf). lim w/o O, glycolysis. minor ATP us when ox phos unavail if no mito or low O.