Galactose formation from glucose

However, in the lactating mammary gland this enzyme associates with milk protein, a-lactalbumin, forming a complex, denoted lactose synthetase, which instead catalyzes the formation of lactose from glucose and UDP-galactose. 

The pentose phosphate pathway is an alternative route for the metabolism of glucose. It does not generate ATP but has two major functions (1) The formation of NADPH for synthesis of fatty acids and steroids and (2) the synthesis of ribose for nucleotide and nucleic acid formation. Glucose, fructose, and galactose are the main hexoses absorbed from the gastrointestinal tract, derived principally from dietary starch, sucrose, and lactose, respectively. Fructose and galactose are converted to glucose, mainly in the liver. 

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