Page 323 - Biology_F5

Biology for Advanced Level Secondary Schools

Pyruvic acid
NAD +
Pyruvate NADH + H +
dehydrogenase
complex CO 2
CoA
Acetyl CoA
(2C)
FOR ONLINE READING ONLY
CoA
Citrate
Oxaloacetate (4C) H O synthetase Citrate (6C)
NADH + H + 2
Aconitase
Malate Fe 2+ H O
2
NAD + dehydrogenase
Malate (4C) Cis-aconitate H O
Aconitase 2
Fe 2+
H O Fumarase Isocitrate (6C)
2
Fumarate (4C) NAD +
Isocitrate
FADH Succinate dehydrogenase NADH + H +
2 dehydrogenase Mn 2-
FAD + Oxalo-succinate (6C)
Succinate (4C)
Oxalosuccinate
ATP/GTR Succinly CoA decarboxylase CO
ADP/GDP CoA synthetase α-Ketoglutarate (5C) 2
Succinly CoA (4C)
CoA NAD +
α-Ketoglutarate
dehydrogenase +
CO 2 complex NADH + H

(a)

Acetyl CoA
CoA CoA
Six carbon
Carbon acceptor molecule formed
molecule from acetyl Co A
(regenerated in NADH + oxaloacetate
each cycle) Oxaloacetate Citrate
NAD +

Malate (4C) NAD +
NADH + CO
2 One carbon
Alpha ketoglutarate molecule lost
Fumarate (4C) NAD + as CO 2

FADH 2 Succinate (4c) NADH + CO 2 Second
carbon
FAD + molecule lost
as CO
2
ATP ADP +Pi
+
(b)
Figure 6.10 Kreb’s cycle (a) detailed diagram and (b) simplified diagram

Form Five Student’s Book
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