Glycogen production

In addition, there are numerous effects of insulin, generally anabolic, not mediated through its well-known effects on glucose transport. For example, in muscle, insulin decreases glycogenolysis and proteolysis. Lipolysis is inhibited by insulin in adipocytes. The effect of insulin on hepatic tissue is to promote increased glycogen production and protein synthesis and to inhibit glycogenolysis, proteolysis, lipolysis, and gluconeogenesis (Fig. 10-1). 

After mention of feedback inhibition and activation, as well as feedforward inhibition, it will be evident that there is a fourth possibility—feedforward activation. This is also rare, but, significantly, when it does occur it is sometimes in pathways that are not demand-driven. We shall meet an example of this shortly when we consider glycogen production in the liver. 

A -Pregnene-3( 8),21-diol-3-one, effect on glycogen production in rat diaphragm, X, 364, 365 A -Pregnene-3 (/3) 2 l-diol-20-one (21-hydroxypregnenolone) adrenocortical origin of urinary, X, 286... 

There is, however, one major disadvantage to the continued combustion of CHO and specifically when the source is muscle glycogen. The capacity for energy production from CHO is finite and much less than from fat (Table 1). Continued... 

When an organism is in steady state, the rates of production and consumption of biomolecules are equal, and there is no net addition to the body on a time scale longer than a few hours (e.g., temporary storage of glucose as glycogen or FAs as fat globules). This is an adequate description of a mature... 

Nucleophilic attack by water generally results in the cleavage of the amide, glycoside, or ester bonds that hold biopolymers together. This process is termed hydrolysis. Conversely, when monomer units are joined together to form biopolymers such as proteins or glycogen, water is a product, as shown below for the formation of a peptide bond between two amino acids. 

Polysaccharides formed from a-glucose are called starches. A starch stores sugar until it is needed for energy production. Three important starches are glycogen, which animals produce in their livers, and amylose and amylopectin, produced by plants through photosynthesis. On average, plant starch is about 20% amylose and 80% amylopectin. Each of these polysaccharides contains glucose as its monomer, but they differ in how the monosaccharide units are linked. 

---