describe the structure of glycogen, and its importance as a carbohydrate reserve.

The monomer of glycogen is:Group of answer choicesA glycerolAn amino acidA glucoseA fatty acid

arbohydrates are stored in plants and animals in which of the following forms respectively?Glycogen, starchGlycogen, glycogenStarch, starchStarch, glycogen

Glycogen molecules are stored in liver and --------------

explain carbohydrates

Dietary carbohydrates are used to synthesize liver glycogen, which exists as particles of various sizes.  During the synthesis of a new glycogen particle, a glucose molecule is linked to the protein glycogenin, after which additional glucose molecules are linked to the first glucose and to each other to form regions that are successively farther from glycogenin.  Glycogen synthesis is catalyzed by the enzyme glycogen synthase, whose activity is inhibited by phosphorylation of three carboxy-terminal serine residues.  During the postabsorptive state (ie, after carbohydrate absorption from a meal is finished), hormone-stimulated release of glucose residues from liver glycogen stores help maintain adequate glucose levels in the blood.Although the important role of liver glycogen in whole-body glucose metabolism has long been appreciated, much remains unknown about the regulation of liver glycogen synthesis and breakdown.  Based on previous studies suggesting a relationship between glycogen particle size and the rate of glycogenolysis, a team of researchers measured the average sizes of liver α and β glycogen particles in wild-type (WT) mice (Table 1).Table 1  Dimensions of Liver Glycogen ParticlesTo better understand the role of the protein glycogenin in glycogen synthesis, the researchers also mated male and female mice that were heterozygous for glycogenin expression (GN +/−) to produce heterozygous offspring as well as mice with WT and knockout (GN −/−) genotypes.  Relative glycogenin gene expression (ie, mRNA levels) was measured in liver and heart samples from the mice (Table 2).  Glycogenin was undetectable in western blots of tissue samples from knockout mice.Table 2  Gene Expression (mRNA Levels Relative to WT) in Liver and Heart Samples.The researchers also measured glycogen concentrations in liver and heart samples from the mice.  The results are presented in Figure 1.Figure 1  Liver and heart glycogen concentrations Question 12The glucagon-induced entry of glucose derived from liver glycogen into the bloodstream for transport to other tissues involves close interaction among which enzymes?A.Glycogen phosphorylase, debranching enzyme, glycogen synthaseB.Glycogen phosphorylase, debranching enzyme, phosphoglucomutase, glucose 6-phosphataseC.Debranching enzyme, phosphoglucomutase, glycogen synthaseD.Debranching enzyme, phosphoglucomutase, phosphofructokinase, glucose 6-phosphatase