Q) Discuss the significance of NAD in cellular respiration
Main points | |
Key idea: | What is NAD |
· Coenzyme, exists in oxidized (NAD+) or reduced state (NADH) | |
Key idea: | Reduced NAD (NADH) |
· NAD - reduced during glycolysis, link reaction and Krebs cycle via dehydrogenation rx · NADH stores energized e + protons (H+); transfers them to ETC at inner mitoch membr, for oxidative phosphorylation | |
Key idea: | Mechanism for the synthesis of ATP |
· Flow of e down energy gradient, energy rel during flow used to pump H+ into thylakoid space (chloroplast) or intermembrane space (mitoch) - forms H+ gradient a/x membrane · Facilitated diffusion of H+ back to mitoch matrix or chloroplast stroma is coupled to synthesis of ATP (phosphorylation of ADP) | |
Key idea: | Quantity of products |
· 1NADH gives rise to 3 ATP · No. of NADH produced by glycolysis, link reaction and Krebs cycle are 2, 2 and 6 per glucose, respectively · 10 NADH contributes to 30 (out of 38) ATP/glucose | |
Key idea: | Role of oxidized NAD (NAD+) |
· Regeneration of NAD+ required for continuation of previous stages of respiration · For continual syn of ATP via substrate-level phosphorylation + oxidative phosphorylation. | |
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) Don’t forget the last point: after NADH and FADH2 donate e to ETC, they return to previous stages | |
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