Q) Describe the Krebs cycle during cellular respiration
Main points | |
Key idea: | Composition + location w/n cell |
· Cyclical series of enz-catalyzed rxs, in mitoch matrix | |
Key idea: | Substrates + intermediate molecules of cycle |
· Acetyl CoA (fr link rx) donates its acetyl gp to oxaloacetate, form citrate, then becomes isocitrate, then isocitrate, then α-ketoglutarate, then succinyl CoA, then succinate, then fumarate, then malate and finally regenerate oxaloacetate | |
Key idea: | Products |
· 1 ATP (via substrate-level phosphorylation) + 3 NADH + 1 FADH2 made per rotation of cycle (rotates x2 / glucose mol) · CO2 as byproduct · Ref to: through decarboxylation + dehydrogenation rx | |
Key idea: | Significance of products |
· Reduced coenz (NADH and FADH2) travel to ETC, at inner mitoch membr, for ATP syn (oxidative phosphorylation) · Regeneration of oxaloacetate for cycle to continue, in O2 | |
Comments: (i) Visualize the answer with the aid of a labelled diagram. (ii) Verbalize the answer + write down the main points w/o referring to the answer (use abbreviations) (iii) Read again within the next 24h & once more within 72h (do not spend more than 10min) (iv) Syllabus only requires an ‘overview’ of the proces, while we included the specific intermediate molecules of the cycle, I personally think only the following are needed for the A level exam – oxaloacetate accepts acetyl group fr acetyl CoA to form citrate and throu a sequential series of rx, oxaloacetate is regenerated | |
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