Relationship of gluconeogenesis to glycolysis

See also Calvin Cycle Reactions, C4 Cycle, Basic Processes of Photosynthesis, Relationship of Gluconeogenesis to Glycolysis (from Chapter 16), Pentose Phosphate Pathway (from Chapter 14)... 

See also Relationship of Gluconeogenesis to Glycolysis, Gluconeogenesis, Lactate Dehydrogenase, Pyruvate, Lactate, Oxaloacetate, L-Malate. 

The relationship of the pentose-phosphate pathway to glycolysis is shown in Figure 20-11. The steps involved in the pentose shunt are readily reversible, but there are several steps in glycolysis that are not. These are the phosphorylation steps (see Figure 20-9). Yet, there has to be a return route from pyruvate to glucose. This route is called gluconeogenesis and, in animals, takes place in... 

In Topic 26 we met the idea that liver and kidney have the enzyme machinery to convert lactate into glucose, the enzymes of gluconeogenesis. Some of these are just the enzymes of glycolysis used backwards. But some are not. In Topic 21, we met a different relationship between liver and kidney the liver has the enzymes to make and export ketone bodies the kidney and also the heart have the enzymes to use them. 

Gluconeogenesis is a process which occurs mainly in the liver and serves to maintain the glucose levels in blood, brain and muscle. The relationship of glycolysis in muscle to gluconeogenesis in liver is indicated in Figure 11.23. 

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