Difference Between Glycolysis and Glycogenolysis

The key difference between Glycolysis and Glycogenolysis is that Glycolysis is the process of breaking down a glucose molecule into pyruvate, ATP and NADH while Glycogenolysis is the process of breaking down glycogen into glucose.

Glucose is the main energy-producing molecule in our body. It is synthesized and broken down into energy molecules by different metabolic pathways. Glycolysis is the initial stage of energy production or the respiration. Therefore, when glucose is in excess, glucose converts into glycogen and stores in muscle and liver tissues. On the other hand, glycogenolysis is the process of breaking glycogen back to glucose during the low energy and low glucose levels.

CONTENTS

1. Overview and Key Difference
2. What is Glycolysis
3. What is Glycogenolysis
4. Similarities Between Glycolysis and Glycogenolysis
5. Side by Side Comparison – Glycolysis vs Glycogenolysis in Tabular Form
6. Summary

What is Glycolysis?

Glucose is the prime source that uses to produce energy for most biochemical reactions. However, the level of glucose in our body should be maintained at a proper level. Glycolysis and gluconeogenesis are two such processes. Gluconeogenesis synthesizes new glucose molecules while glycolysis breaks down glucose into pyruvate, ATP and NADH. Therefore, glycolysis is one of the three main processes of cellular respiration.  Moreover, the other two processes are the Krebs cycle and electron transport chain.

Glycolysis takes place in the cytoplasm of the cells. Thus, it can occur either in the presence or the absence of oxygen. There are two main phases of glycolysis; energy requiring phase and energy releasing phase. Furthermore, glycolysis has ten steps that catalyze by different enzymes. One glucose molecules convert into two pyruvate molecules via Glucose 6-phosphate, Fructose 6-phosphate, Fructose 1,6-bisphosphate, Glyceraldehyde 3-phosphate, 1,3-Bisphosphoglycerate, 3-Phosphoglycerate, 2-Phosphoglycerate and Phosphoenolpyruvate.

What is Glycogenolysis?

Glycogen is the storage form of glucose. It is a large polymer of glucose mainly stored in the liver and skeletal muscle. During the times of low glucose and low energy, glycogen can be readily broken down to glucose via the process called glycogenolysis. Hence, glycogenolysis is the mechanism that converts glycogen into glucose molecules.

Moreover, it occurs in the cells of the muscle and liver tissues. This process yields products such as Glycogen_{(n-1 residues)}  and Glucose-1-phosphate. Glycogenolysis is important for maintaining the blood glucose level.

What are the Similarities Between Glycolysis and Glycogenolysis?

• Both processes are related to Glucose molecule.
• Enzymes catalyze both of them.
• Both are important to maintain the proper levels of glucose in the body.

What is the Difference Between Glycolysis and Glycogenolysis?

Glucose converts into pyruvate by glycolysis. On the other hand, glycogen which is the storage form of glucose converts into glucose by glycogenolysis. This is the key difference between glycolysis and glycogenolysis. Moreover, glycolysis occurs in the cytoplasm of the cells while glycogenolysis occurs in the muscle and liver tissue cells. Both processes contribute to the energy production and maintenance of glucose level in our body.

Summary – Glycolysis vs Glycogenolysis

Glycolysis and glycogenolysis are two processes which break glucose into pyruvate and glycogen into glucose respectively. Glycolysis is the initial step of cellular respiration, and it occurs in the cytosol of the cells. Glycogenolysis, on the contrary, occurs in the cells of muscle and liver tissues. Both processes are important since they help to regulate the glucose level in the body. This is the difference between glycolysis and glycogenolysis.

Reference:

1.“Glycolysis.” Khan Academy, Khan Academy. Available here
2.Britannica, The Editors of Encyclopaedia. “Glycogenolysis.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 22 Nov. 2016. Available here

Image Courtesy:

1.’Glycolysis-2’By Glycolysis.svg: WYassineMrabetTalk (CC BY-SA 3.0) via Commons Wikimedia  
2.’Glycogenolysis 1st step’By Mertmetin96 – Own work, (CC BY-SA 4.0) via Commons Wikimedia