Glucose in glycogen

Spectrometer can measure the amount of glycogen from the content of C-labelled glucose in glycogen in Uver or muscle of a volunteer (for description of isotopes, see Appendix 2.2). This is a non-invasive technique, but it gives similar results to the biopsy method (Chapter 16) (Appendix 2.3). 

This is equivalent to an ATP production of about 3 pmol per s per g (one molecule of glucose-in-glycogen when converted to lactic acid generates three molecules of ATP) so the rate of ATP generation is (0.83 x 3.0) approximately 3 pmol per s per g fresh weight (Appendix 13.3). 

UTP is a also used to activate sugars for polysaccharide synthesis, such as the reaction below, which activated glucose in glycogen biosynthesis ... 

In addition to their important roles as the building blocks of macromolecules, the monomers perform other important functions. Certain coenzymes, e.g. NAD, FAD, coenzyme A (Section 5.2), contain nucleotide structures. The chemical form in which energy is carried and from which it is released in the cell is ATP, a nucleotide. Some nucleotides are involved in carbohydrate biosynthesis as glycosyl carriers, e.g. UDP-glucose in glycogen biosynthesis. Glucose and fatty acids serve as major sources of energy in many cells. Individual amino... 

The primary hormone responsible for conversion of glucose to glycogen is insulin (Figure 6.36). Insulin is secreted by special cells in the pancreas called the islets of Langerhans. Secretion of insulin is a response to increased glucose in the... 

The insulin receptor is a transmembrane receptor tyrosine kinase located in the plasma membrane of insulin-sensitive cells (e.g., adipocytes, myocytes, hepatocytes). It mediates the effect of insulin on specific cellular responses (e.g., glucose transport, glycogen synthesis, lipid synthesis, protein synthesis). 

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... 

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

Figure 18-7. Control of glycogen synthase in muscle (n = number of glucose residues). The sequence of reactions arranged in a cascade causes amplification at each step, allowing only nanomole quantities of hormone to cause major changes in glycogen concentration. (GSK, glycogen synthase kinase-3, -4, and -5 G6P, glucose 6-phosphate.)...

Glycogenolysis The process by which glycogen is broken down to glucose in body tissues. 

During the recovery period from exercise, ATP (newly produced by way of oxidative phosphorylation) is needed to replace the creatine phosphate reserves — a process that may be completed within a few minutes. Next, the lactic acid produced during glycolysis must be metabolized. In the muscle, lactic acid is converted into pyruvic acid, some of which is then used as a substrate in the oxidative phosphorylation pathway to produce ATP. The remainder of the pyruvic acid is converted into glucose in the liver that is then stored in the form of glycogen in the liver and skeletal muscles. These later metabolic processes require several hours for completion. 

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