Glucose glycogen, storage

Starch and glycogen are storage polymers of glucose in plants and animals, respectively. Starch is the major source of energy in the diet. 

Increase in glycogenesis (formation of glycogen, the storage form of glucose)... 

Promotes glucose storage as glycogen (induces glucokinase and glycogen synthase, inhibits phosphorylase)... 

Carbohydrates, like glucose, are not synthesized de novo by parasitic flatworms, and gluconeogenesis has never been demonstrated except from intermediates at the level of triose phosphates (Bryant and Behm, 1989). Simple carbohydrates are obtained from the host and are then used by the parasite to synthesize complex ones, for instance, production of the glycocalyx glycoproteins or the synthesis of glycogen, the storage carbohydrate used by all parasitic flatworms. 

Growth factor receptors (These receptors fall into two main groups receptor tyrosine kinases and receptors that associate with cytoplasmic tyrosine Insulin1 Insulin Lower blood glucose promote glucose storage as glycogen in liver and skeletal muscle and as fat in fat cells... 

Conversion of excess glucose into glycogen for storage (this can later be converted back to glucose for energy). 

The catalytic activity of enzymes is controlled in several ways. Reversible allosteric control is especially important. For example, the first reaction in many biosynthetic pathways is allosterically inhibited by the ultimate product of the pathway. The inhibition of aspartate trans carbamoyl as e by cytidine triphosphate (Section 10.1) is a well-understood example offeedback inhibition. This type of control can be almost instantaneous. Another recurring mechanism is reversible covalent modification. For example, glycogen phosphorylase, the enzyme catalyzing the breakdovm of glycogen, a storage form of sugar, is activated by phosphorylation of a particular serine residue when glucose is scarce (Section 21.2.1). 

Acetyl CoA is the fuel for the citric acid cycle. This important molecule is formed from the breakdown of glycogen (the storage form of glucose), fats, and many amino acids. Indeed, as we will see in Chapter 22. fats contain strings of reduced two-carbon units that are first oxidized to acetyl CoA and then completely oxidized to CO2 by the citric acid cycle. 

Glycogen The storage form of glucose in tissues. It is a large polysaccharide composed of glucose residues in primarily a(1 4) glycosidic linkages with some a(l—>6) branch points. 

Glucose is converted into glycogen, the storage form of glucose in mammals, in a process regulated by insulin and insulin-mediated activation of protein phosphatase 1 (PPl). 

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