Cheatography
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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 |
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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. |
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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. |
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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 |
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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 |
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TCA cycle
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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
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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 |
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