Carbohydrate Metabolism

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Carbohydrates are the cells’ primary source of energy and are considered essential for each metabolic process. Other than that, certain carbohydrates serve as a structural component of tissues, while others formulate the prosthetic group of hormones, blood group substances, immunoglobulin, etc. 

Deoxyribose and ribose come in handy in synthesising nucleic acids and nucleotides. Furthermore, in anaerobic condition, glucose can be used as energy. 

In diet, carbohydrates are mostly polysaccharides in the form of cellulose, glycogen, starch, etc. 

Besides that, disaccharides and monosaccharides are found in one’s diet. The molecular formula of a simple monosaccharide or sugar is expressed as C6H12O6C6H12O6C6H12O6. 

Keeping this in mind, let’s now focus our emphasis on carbohydrate metabolism and its role in general. 

What is Carbohydrate Metabolism?

It can be described as the primary biochemical process which is responsible for the formation, breakdown and conversion of carbohydrates in all living beings. Through the process, energy is supplied to all living cells.

Arguably, glucose is an essential carbohydrate which is broken down through glycolysis. Subsequently, the Krebs cycle sets in motion and enters the oxidative phosphorylation to release ATP. 

Notably, other vital pathways involved in carbohydrate metabolism include the pentose phosphate pathway, wherein hexose sugars are converted into pentose. Likewise, glycogenolysis is responsible for converting excess glucose into glycogen when stimulated by insulin. 

Further, glycogenolysis converts glycogen polymers to glucose when stimulated by glucagon. Take a look at this image below to gain an idea about the carbohydrate metabolism steps.

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Test Your Knowledge

 __________ is the site of gluconeogenesis.

  1. Liver b) Brain c) Blood d) Muscles.


Glycolysis is a metabolic pathway that breaks hexose monosaccharides like glucose, fructose and galactose into pyruvate molecules, water, energy and ions.  

Typically, there are 10 steps in glycolysis which are mediated closely by enzymes. Nonetheless, they can be categorised under two broad phases – phosphorylation and production of energy.

Glucose is the most readily available energy source in the human body. Once polysaccharides are broken down into monosaccharides through the digestive process, the monosaccharides are carried to the circulatory system.

Subsequently, it gets transported to the liver, where the hepatocytes either store the excess glucose in the form of glycogen or pass it on through the circulatory system. Also, glycolysis is a series of reactions which aid glucose absorption by the cells as a reaction to insulin. 

In turn, the energy present in glucose is transferred to ADP to produce ATP, which further produces pyruvate as a by-product. 

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Test Your Knowledge

Which enzyme is responsible for converting pyruvate into phosphoenolpyruvate?

  1. Glucose 6-phosphatase.

  2. Pyruvate carboxylase.

  3. Phosphofructokinase.

  4. Pyruvate carboxykinase.

Disorders of Carbohydrate Metabolism

Improper carbohydrate metabolism can cause numerous diseases. Following are some of the most common ones –

  • Diabetes Mellitus: It occurs due to the lack of insulin or resistance to it, which further leads to either hyper or hypoglycemia.

  • Lactose Intolerance: Fundamentally, it is an allergy that is common in adults. It mostly occurs due to the deficiency of the enzyme lactase. This enzyme is responsible for the conversion of lactose disaccharides into glucose monosaccharides. 

  • Galactosemia: This particular disorder is quite rare. It is caused due to congenital mutations in enzymes which are a part of glucose metabolic pathways. 

DIY: Gierke’s disease is another carbohydrate metabolism disease. Look it up and find out its causes and effect on human beings. 

Do you want to find out about the role of carbohydrates in metabolism? Join our live online classes and find out about it from the subject experts. Also, you can access chapter-wise study solutions to gain clarity over the topic and other associated concepts.

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FAQ (Frequently Asked Questions)

1. What is Carbohydrate Metabolism?

Ans. It is a biochemical process which supplies energy to the living cells. To elaborate, it is responsible for the formation, breakdown and conversion of carbohydrates in all living organisms. 

2. What is Glycolysis?

Ans. Glycolysis is a process of breaking down glucose molecules into pyruvate molecules. It is also responsible for storing energy like ATP and NADH.

What is Carbohydrate Metabolic Disorders?

Ans. They are metabolic disorders which arise due to improper carbohydrate metabolism because of improper functioning of enzymes. Some of the most common diseases include – diabetes mellitus, lactose intolerance, fructose malabsorption and galactosemia.