Biochem Chapter 13 Gluconeogenesis Glycogen Synthesis Pentose Pathway

gluconeogenesis

pathway that converts pyruvate and related 3 and 4 carbon compounds to glucose

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bypassed reactions of gluconeogenesis

pyruvate carboxylase

First bypass 1: mitochondrial enzyme that converts pyruvate to oxaloacetate, requires coenzyme biotin and ATP

phosphoenolpyruvate carboxykinase (PEPCK)

First bypass 2: converts oxaloacetate to PEP, requires Mg2+ and GTP

fructose 1,6-bisphosphate

Second bypass: converts fructose 1,6-bisphosphate to fructose 6-phosphate by hydrolysis of the C-1 phosphate, requires Mg2+, irreversible

glucose 6-phosphate

Third bypass: catalyzes the simple hydrolysis of glucose 6-phosphate to glucose, found in the ER

4 ATP 2 GTP 2 NADH

cost of gluconeogenesis

regulated

gluconeogenesis is ____ at the fructose bisphosphate step, activate gluconeogenesis turns off glycolysis

glycogenolysis

the breakdown of cellular glycogen to glucose 1-phosphate

glycogenesis

the synthesis of glycogen

phosphoglucomutase

converts glucose 6-phosphate to glucose 1-phosphate

linear

glycogen synthase adds glucose to extend the glycogen polymer

glycogen branching enzyme

catalyzes the formation of the bonds found at the branch points of glycogen (cut and paste)

glycogen phosphorylase

cleaves, breakdown bonds of glycogen chain

debranching enzyme

transfers branches onto main chains and releases the residue at the branch as free glucose

liver

tissue containing glucose 6 phosphatase

ribose-5-phosphate NADPH

products of pentose phosphate pathway

fatty acid synthesis

NADPH in pentose phosphate pathway is used as

rapidly divide cells

ribose-5-phosphate in pentose phosphate pathway is used in nucleotide synthesis to