Ch 17.3 Text

·         The Citric acid cycle also provides __ for biosynthesis. For example, most of the carbon atoms in __ come from __. Many of the amino acids are derived from __ and __
·         Citric acid cycle intermediates must be __if any are __
o   The CAC will operate to a reduced extent unless new __is formed, because acetyl CoA cannot enter the cycle unless it __; a minimal level mst be maintained to allow the cycle to function 

·         How is oxaloacetate replenished? 

·         __ plays a crucial role in __. It is active only in the presence of __, which signifies __
o   If the energy charge is high, oxaloacetate is __. If the energy charge is low, oxaloacetate __

§  The synthesis of oxaloacetate by the carboxylation of pyruvate is an __, a reaction that leads to the net synthesis, or replenishment of pathway components

·         __, a neurologic and cardiovascular disorder, is caused by a __
o   It is partly ameliorated if the __; some of the thiamine in the husk then leaches into the rice kernel
o   The problem is exacerbated if the rice is __, because ony the outer layer contains significant amounts of thiamine

o   Characterized by __ and __ 
§  Damage to the peripheral nervous system is expressed as __(3)__; the heart may be enlarged and the cardiac output inadequate

·         thiamine is the precursor of the __.
o   This cofactor is the prosthetic group of three important enzymes: __(3)__
§  __functions in the pentose phosphate pathway

o   The common feature of enzymatic reactions utilizing TPP is the __
§  In beriberi, the levels of __ and __ in the blood are higher than normal
·         The increase in the level of __in the blood is especially pronounced after the ingestion of glucose

·         The nervous system relies on __as its only fuel. The product of glycolysis, __, can enter the CAC only through the __
o   With that enzyme deactivated, the NS has no source of fuel; other tissues can use __as a source of fuels for the CAC

·         Symptoms similar to those of beriberi appear in organisms exposed to __ or __. Both materials have a high affinity for neighboring __, such as those in the reduced __ of the __

o   The binding of mercury or arsenite to the dihydrolipoyl groups does what?

·         Treatment for these poisons is the __
o   The reagent-metal complex is excreted in the urine
§  2,3-dimercaptopropanol was developed for it

·         The CAC was most likely assembled from preexisting reaction pathways. Many of the intermediates formed in the citric acid cycle are used in __
o   Thus, compounds like __ were present early in evolution for biosynthetic purposes

§  The __ of these __ is favorable thermodynamically and can be used to drive the synthesis of both acyl CoA derivatives and NADH
·         These reactions almost certainly formed the core of processes that preceded the CAC evolutionarily

o   Interestingly, __ can be directly converted into __by __ of the respective amino acids by __, another key biosynthetic enzyme
Thus, cycles comprising smaller numbers of intermediates used for a variety of biochemical purposes could have existed before the present form evolved.