glucose

Examples of glucose in the following topics:

• Polysaccharide Biosynthesis

  • Polysaccharides are synthesized from two forms of activated glucose molecules: UDP-glucose and ADP-glucose.
  • There are two forms of activated glucose: UDP-glucose and ADP-glucose.
  • Uridine diphosphate glucose (uracil-diphosphate glucose, UDP-glucose) is a nucleotide sugar.
  • Components UDP-glucose consists of the pyrophosphate group, the pentose sugar ribose, glucose, and the nucleobase uracil .
  • UDP-Glucose consists of the pyrophosphate group, the pentose sugar ribose, glucose, and the nucleobase uracil.

• Glucosuria

  • Glycosuria or glucosuria is the excretion of glucose into the urine .
  • Ordinarily, urine contains no glucose because the kidneys are able to reclaim all of the filtered glucose back into the bloodstream.
  • When the blood glucose level exceeds about 160 – 180 mg/dl, the proximal tubule becomes overwhelmed and begins to excrete glucose in the urine.
  • This point is called the renal threshold of glucose (RTG).
  • With normal kidney (renal) function, glucose is excreted in the urine only when there are abnormally elevated levels of glucose in the blood.

• Hormonal Regulation of Metabolism

  • Insulin lowers blood glucose levels by enhancing the rate of glucose uptake and utilization by target cells, which use glucose for ATP production.
  • This prevents glucose from being absorbed by cells, causing high levels of blood glucose, or hyperglycemia (high sugar).
  • High blood glucose levels make it difficult for the kidneys to recover all the glucose from nascent urine, resulting in glucose being lost in urine.
  • As the levels of glucose in the blood rise, insulin stimulates the cells to take up more glucose and signals the liver to convert the excess glucose to glycogen, a form in which it can be stored for later use.
  • When the levels of glucose in the blood fall, glucagon responds by stimulating the breakdown of glycogen into glucose and signals the production of additional glucose from amino acids.

• Connecting Other Sugars to Glucose Metabolism

  • But living things consume more than glucose for food.
  • Glycogen, a polymer of glucose, is an energy-storage molecule in animals.
  • The glycogen is hydrolyzed into the glucose monomer, glucose-1-phosphate (G-1-P), if blood sugar levels drop.
  • The catabolism of sucrose breaks it down to monomers of glucose and fructose.
  • The entire globular granule may contain around 30,000 glucose units.

• Connecting Lipids to Glucose Metabolism

  • Lipids can be both made and broken down through parts of the glucose catabolism pathways.
  • Like sugars and amino acids, the catabolic pathways of lipids are also connected to the glucose catabolism pathways.
  • The lipids that are connected to the glucose pathways are cholesterol and triglycerides.
  • Thus, synthesis of cholesterol requires an intermediate of glucose metabolism.
  • Triglycerides can be both made and broken down through parts of the glucose catabolism pathways.

• Carbohydrate Molecules

  • Plants synthesize glucose using carbon dioxide and water, and glucose, in turn, is used for energy requirements for the plant.
  • Plants are able to synthesize glucose, and the excess glucose is stored as starch in different plant parts, including roots and seeds.
  • The cells can then absorb the glucose.
  • It is made up of monomers of glucose.
  • Whenever blood glucose levels decrease, glycogen is broken down to release glucose in a process known as glycogenolysis.

• Connecting Proteins to Glucose Metabolism

  • Excess amino acids are converted into molecules that can enter the pathways of glucose catabolism.
  • They can be broken down into their constituent amino acids and used at various steps of the pathway of glucose catabolism.
  • When deaminated, amino acids can enter the pathways of glucose metabolism as pyruvate, acetyl CoA, or several components of the citric acid cycle.
  • For example, deaminated asparagine and aspartate are converted into oxaloacetate and enter glucose catabolism in the citric acid cycle.
  • Several amino acids can enter glucose catabolism at multiple locations.

• Importance of Glycolysis

  • Glycolysis is the first step in the breakdown of glucose to extract energy for cellular metabolism.
  • Glucose enters heterotrophic cells in two ways.
  • These transporters assist in the facilitated diffusion of glucose.
  • Glycolysis is the first pathway used in the breakdown of glucose to extract energy.
  • Glycolysis is the first pathway of cellular respiration that oxidizes glucose molecules.

• Interactions of Hormones at Target Cells

  • Liver and muscle cells convert glucose to glycogen, for short term storage, and adipose cells convert glucose to fat.
  • In response, glucose concentration decreases in the blood, and insulin secretion discontinues through negative feedback from declining levels of glucose.
  • Glucagon stimulates the liver to release glucose .
  • The glucose in the liver originates from the breakdown of glycogen.
  • Glucagon is a pancreatic peptide hormone that, as a counterregulatory hormone for insulin, stimulates glucose release by the liver and maintains glucose homeostasis.

• Pancreatic Islet Disorders: Diabetes and Hyperinsulinism

  • Normal insulin secretion and blood levels are closely related to the level of glucose in the blood, so that a given level of insulin can be normal for one blood glucose level but low or high for another.
  • Also known as Hyperglycæmia, or high blood sugar, this is a condition in which an excessive amount of glucose circulates in the blood plasma.
  • This is generally a glucose level higher than (200 mg/dl).
  • Hypoglycemia, or low blood sugar (not to be confused with hyperglycemia) is an abnormally-diminished content of glucose in the blood.
  • Most healthy adults maintain fasting glucose levels above 4.0 mmol/L (72 mg/dl), and develop symptoms of hypoglycemia when the glucose falls below 4 mmol/L.