Gluconeogenesis Glucose

The amino acids are required for protein synthesis. Some must be supplied in the diet (the essential amino acids) since they cannot be synthesized in the body. The remainder are nonessential amino acids that are supplied in the diet but can be formed from metabolic intermediates by transamination, using the amino nitrogen from other amino acids. After deamination, amino nitrogen is excreted as urea, and the carbon skeletons that remain after transamination (1) are oxidized to CO2 via the citric acid cycle, (2) form glucose (gluconeogenesis), or (3) form ketone bodies. 

Key PEP-CK = PEP carboxykinase this enzyme begins the re-cycling of carbon atoms derived from amino acids (via pyruvate, 2-OG or OAA) or lactate (via pyruvate) to glucose (gluconeogenesis). 

Liver ATP used in synthesis of glucose (gluconeogenesis) during recovery. 

Low Blood Glucose —> (+) gluconeogenesis (decreasing "C" supply for lipogenesis). 

Lactate released from cells undergoing anaerobic glycolysis is taken up by other tissues (primarily the liver, heart, and skeletal muscle) and oxidized back to pyruvate. In the liver, the pymvate is used to synthesize glucose (gluconeogenesis), which is returned to the blood. The cycling of lactate and glucose between peripheral tissues and liver is called the Cori cycle (Fig. 22.10). 

Glucose-6-phosphate can be converted to glucose (gluconeogenesis), glycogen, pentose phosphates (pentose phosphate pathway), or pyruvate (glycolysis). 

The synthesis of glucose (gluconeogenesis), which is then stored as starch (a mixture of a-glucose polymers, vide infra) and/or cellulose (a mixture of P-glucose polymers, vide infra), occurs by condensation of 3-phosphoglyceraldehyde (glycer-aldehyde 3-phosphate) with dihydroxyacetone monophosphate (Scheme 11.13). 

---