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metabolism Cheat Sheet (DRAFT) by

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This is a draft cheat sheet. It is a work in progress and is not finished yet.

enzyme­-driven reactions

break down food to produce energy (catab­olism), stored as ATP & electron carriers: NADH, NADPH2, FADH2
build up from biomol­ecules (anabo­lism), requiring energy in form of phosphoryl group transfer from ATP & reducing power of NADH & NADPH
eliminate waste
grow & reproduce, maintain structures & respond to enviro­nment
drive desirable energy­-re­quiring reactions by coupling them to sponta­neous energy­-re­leasing reactions

glycolysis

cytoplasm
1. phosphate group transf­erred from ATP to glucos­e-6­-ph­osp­hate. Catalysed by hexoki­nase. 1 molecule of ATP used
2. Glucos­e-6­-ph­osphate converted to isomer fructo­se-­6-p­hos­phate by phosph­ogl­ucose isomerase enzyme
3. second ATP molecule used to phosph­orylate fructo­se-­6-p­hos­phate to produce fructo­se-­1,6­-bi­sph­osp­hate. catalysed by phosph­ofr­uct­oki­nase.
4. fructose 1,6-bi­sph­osphate is split into 2x 3C sugars by adolase. these are glycer­ald­ehy­de-­3-p­hos­phate & dihydr­oxy­acetone phosphate
5. DHAP converted to GAP by triose phosphate isomerase
6. G3P dehydr­ogenase enzyme catalyses two processes: it oxidises GAP, & at the same time NAD+ is reduced to NADH + H+. overall reaction releases energy that is used to phosph­orylate GAP, creating 2 x 1,3-bi­sph­osp­hog­lyc­erate molecules.
7. each of the two BPG molecules donate a phosphate group to an ADP, forming 2 x ATP & two molecules of 3-phos­pho­gly­cerate. catalysed by phosph­ogl­ycerate kinase.
8. phosph­ogl­yce­rom­utase converts two 3 PGA into 2 molecules of 2-phos­pho­gly­cerate (isomers)
9. enolase removes a water molecule from each of 2PGA, creating two molecules of phosph­oen­olp­yruvate
10. phosphate group transf­erred from PEP to ADP, creating 2 x ATP & 2x pyruvate. catalysed by pyruvate kinase.

glycosis notes

1. 6th c is phosph­ory­lated as it is the most exposed. neg charge addition of phosphate prevents g6p from leaving cytosol. Delta g negative & irreve­rsible.
2. isomer­isation rearranges atoms to present another C for phosph­ory­lation. delta g 0, revers­ible.
3. delta g negative & irreve­rsible.
4. lysis. previous phosphates added makes fructose easier to break due to charge redist­rib­ution. products used up quickly, pushing equil to right. delta g positive & irreve­rsible.
5. isomer­isation moves carbonyl to generate g3p which is more reactive. delta g positive & revers­ible.
6. redox generates highly reactive acyl phosphate interm­ediate & NADH. enzyme is dehydr­ogenase because it takes H off first C. Delta g 0, revers­ible.
7. sub-level phosph­ory­lation. delta g large, neg & irreve­rsible.
8. isomer­isation moves phosphate from 3rd to 2nd position to make molecule more reactive, delta g 0, revers­ible.
9. dehydr­ation. delta g 0, revers­ible.
10. sub-level phosph­ory­lation. delta g negative & irreve­rsible.

anaerobic reduction of pyruvate to lactate

during vigorous exercise, pyuvate production > pyruvate oxidation (by citric acid cycle)
red blood cells lack mitoch­ondria, produce lactate
the 2x NADH are oxidised to 2x NAD+ by lactate dehydr­ogenase to regenerate NAD+ & maintain redox balance

Gibbs free energy

amount of free energy available is related to the difference in energy levels between products & reactions
if +/- 10 kj/mol = at equil
if over 10 kj/mol = favours substrate, little product
if under - 10 kj/mol = favours product, little substrate

TCA cycle

Can Intell­igent Karen Solve Some Foreign Mafia Operat­ions?
Link: pyruvate from glycolysis is decarb­oxy­lated to form acetyl-CoA by pyruvate dehydr­oge­nase.
1. (conde­nsa­tion), acetyl-CoA (2C) joins oxaloc­etate (4C) to form citrate (6c) + CoA. catalysed by citrate synthase. delta G neg & irr.
2. citrate converted to isocitrate isomer. catalysed by aconitase. dehydr­ation & hydration step alter position of H/OH. delta G positive & irr.
3. isocitrate oxidised to alpha-­ket­ogl­utarate (5C) resulting in release of CO2. 1 x NADH2 molecule formed. catalysed by isocitrate dehydr­oge­nase.
4. alpha-­ket­ogl­utarate oxidised to form 4C molecule succinate that binds to CoA forming succinal CoA. catalysed by alpha-­ket­ogl­utarate dehydr­ogenase complex. 2nd NADH produced & 2nd O2. delta G = neg & irr.
5. succinyl coA to succinate (4C) & one GTP produced. catalysed by succin­ylc­hlo­rin­e-CoA synthe­tase. delta g = 0 & rev
6. succinate to fumerate (4C) & molecule of FADH2 produced. delta G = 0 & rev. catalysed by succinate dehydr­oge­nase.
7. fumarate to malate (4C). hydration, catalysed by fumerase. delta G =0, revers­ible.
8. malate to oxaloa­cetate, 3rd NADH produced. dehydr­oge­nation to make oxaloa­cetate to keep cycle going. catalysed by malate dehydr­oge­nase. delta G = pos & irr.
cycle occurs twice - one for each pyruvate

oxidative phosph­ory­lation: e- transport chain

NADH, FADH2 have electrons in high energy states that move from NADH, FADH2, reducing O2 to H2O & energy is transf­erred to protein complexes
Energy from oxidising NADH, FADH2 used to pump H+s into interm­embrane space
Interm­embrane space more acidic than matrix – creates electr­och­emical gradient
Flow of H+s down electr­och­emical gradient used to generate ATP
electron transfer with transfer of H+ protons across inner mitoch­ondria membrane used to create electr­och­emical gradient & generate ATP
 

end products