41 - the most crucial regulators of the citric acid cycle are its substrates , acetyl co A and oxaloacetate , and its product , NADH .
the above statement is true .
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42 - which enzyme of the citric acid cycle is very similar structurally and mechanistically to lactate dehydrogenase and alcohol dehydrogenase ?
a- alpha ketoglutarate dehydrogenase
b- succinate dehydrogenase
c- NAD + dependent isocitrate dehydrogenase
d- malate dehydrogenase
answer is d .
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43 - the thiamine pyrophosphate ( TPP ) a cofactor is bound to E1 and decarboxylates pyruvate , yielding a hydroxyethyl TPP carbon ion .
the above statement is true .
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44 - several biosynthetic pathways use citric acid cycle intermediates as starting material for anabolic reactions .
the above statement is true .
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45 - lipoamide consists of lipoic acid covalently joined to the epsilon - amino group of a lysine residue via an amide bond .
the above statement is true .
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46 - how is flux through out the citric acid controlled ?
a- primarily by control of citrate synthase
b- primarily by control of isocitrate dehydrogenase
c- primarily by control of alpha ketoglutarate dehydrogenase
d- at many points , including all the above
answer is d .
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47 - alpha ketoglutarate dehydrogenase is a multienzyme complex containing alpha ketoglutarate dehydrogenase ( E 1 ) , dihydro lipoyl trans succinylase ( E2 ) and dihydro lipoyl dehydrogenase .
the above statement is true .
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48 - in pyruvate dehydrogenase which cofactor is used to decarboxylate pyruvate?
a- TPP
b- lipoic acid
c- co A
d- FAD
the answer is a .
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49 - describe the regulatio of the conversion of isocitrate to alpha keto glutarate ?
a- calcium and ADP stimulate , NADH AND ATP inhibit .
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50 - Isocitrate lyase and malate sythase occur in both plants and animals .
the above statement is false . these enzymes occur only in plants .
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51 - acetyl co A is formed from pyruvate through oxidative decarboxylation by a multienzyme complex named ?
answer is pyruvate dehydrogenase .
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52 - which three compounds associated with the citric acid cycle inhibit their own synthesis ?
answer is acetyl co A , citrate and succinyl co A .
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53 - the tight coupling of oxygen consumption , NADH reoxidation and ATP production in the citric acid cycle requires regulation by feedback mechanisms that coordinate NADH Production with energy expenditure .
true.
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