18 Aug, 2024
· Biology

Which hormone stimulates the breakdown of polymerized glucose

  • Insulin
  • Plant starch
  • Glucagon
  • Glycogen
Short Answer
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Long Explanation

Explanation

Hormone Stimulating Breakdown of Polymerized Glucose

The hormone responsible for stimulating the breakdown of polymerized glucose is glucagon. Glucagon plays a crucial role in glucose metabolism by promoting the degradation of glycogen into glucose.

Glycogenolysis Process

Glucagon triggers a biochemical pathway known as glycogenolysis, which involves the conversion of glycogen stored in the liver into glucose. The key reactions involved can be represented as:

Glycogen→Glucose-1-Phosphate→\text{Glycogen} \rightarrow \text{Glucose-1-Phosphate} \rightarrow →Glucose-6-Phosphate→Glucose\rightarrow \text{Glucose-6-Phosphate} \rightarrow \text{Glucose}

Where:

  • Glycogen is the polymerized form of glucose.
  • Glucose-1-Phosphate and Glucose-6-Phosphate are intermediates in this pathway.
  • Glucose is the final product released into the bloodstream to maintain blood sugar levels.

Role of Glucagon

  • Glucagon binds to specific receptors on liver cells, initiating a signaling cascade that activates the enzyme glycogen phosphorylase.
  • Glycogen Phosphorylase catalyzes the cleavage of α-1,4-glycosidic bonds in glycogen.
  • This enzymatic action results in the production of glucose-1-phosphate, which is subsequently converted into glucose-6-phosphate.

Importance in Homeostasis

Glucagon ensures homeostasis by:

  • Increasing blood glucose levels during fasting or low-carbohydrate intake.
  • Supporting energy availability when immediate demands arise.

By performing these functions, glucagon is essential in regulating energy supply and balancing metabolic activities within the body.

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Rebecca Green

Biology and Health Content Writer at Math AI

Rebecca Green, who recently completed her Master's in Biology from the University of Cape Town, works as a university lab teaching assistant and a part-time contract writer. She enjoys making biology fun and accessible through engaging content.

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Concept

Glucagon

Overview of Glucagon

Glucagon is a peptide hormone, produced by the alpha cells of the pancreas, which plays a crucial role in maintaining glucose homeostasis in the body. It works in opposition to insulin, another important hormone produced by beta cells of the pancreas.

Function of Glucagon

The primary function of glucagon is to increase blood glucose levels when they are too low. This is achieved through several key processes:

  1. Glycogenolysis: Glucagon stimulates the liver to break down glycogen into glucose.
  2. Gluconeogenesis: It promotes the production of glucose from non-carbohydrate sources, such as amino acids and fatty acids.
  3. Lipolysis: Glucagon also aids in the breakdown of fats into free fatty acids and glycerol, which can be used for energy.

Mechanism of Action

Glucagon binds to receptors on liver cells, initiating a cascade of reactions. This involves the activation of adenylate cyclase, which increases the levels of cyclic AMP (cAMP) and activates protein kinase A (PKA). As a result, enzymes involved in glycogenolysis and gluconeogenesis are activated.

Clinical Significance

Glucagon's role is vital in conditions such as diabetes mellitus. In Type 1 diabetes, the lack of insulin leads to an unregulated effect of glucagon, causing elevated blood glucose levels. Glucagon is also used therapeutically in emergencies to treat severe hypoglycemia.

By understanding its function, health professionals can better manage metabolic disorders and ensure proper glucose regulation.

Concept

Glycogenolysis

Explanation

Glycogenolysis is the biochemical process of breaking down glycogen into glucose, which occurs primarily in the liver and muscle cells. This process is critical for maintaining blood sugar levels and supplying energy during periods of fasting or intense physical activity.

Key Steps

  1. Phosphorylation of Glycogen: Glycogen phosphorylase catalyzes the cleavage of α-1,4 glycosidic bonds in glycogen, adding a phosphate group to produce glucose-1-phosphate.
(C6H10O5)n+H3PO4→\mathrm{(C_6H_{10}O_5)}_{n} + H_3PO_4 \rightarrow →(C6H10O5)n−1+C6H11O9P\rightarrow \mathrm{(C_6H_{10}O_5)}_{n-1} + \mathrm{C_6H_{11}O_9P}

  1. Conversion of Glucose-1-Phosphate to Glucose-6-Phosphate: Glucose-1-phosphate is converted into glucose-6-phosphate by the enzyme phosphoglucomutase.

    C6H11O9P→C6H13O9P\mathrm{C_6H_{11}O_9P} \rightarrow \mathrm{C_6H_{13}O_9P}

  2. Formation of Free Glucose: In the liver, glucose-6-phosphate can be dephosphorylated by glucose-6-phosphatase to release free glucose into the bloodstream.

    C6H13O9P+H2O→C6H12O6+H3PO4\mathrm{C_6H_{13}O_9P} + H_{2}O \rightarrow \mathrm{C_6H_{12}O_6} + \mathrm{H_{3}PO_{4}}

Importance

  • Energy Supply: During intense physical activity, muscle glycogen is broken down to provide an immediate energy source.
  • Blood Sugar Regulation: The liver uses glycogenolysis to maintain adequate glucose levels in the blood, especially during fasting.

Regulation

Glycogenolysis is tightly regulated by hormonal signals:

  • Glucagon and epinephrine stimulate glycogenolysis to release glucose into the blood.
  • Insulin inhibits glycogenolysis to promote glycogen synthesis and storage.