Carbohydrate metabolism

Carbohydrate Metabolism

Carbohydrate metabolism (pronunciation: /ˌkɑːrboʊˈhaɪdreɪt mɪˈtæbəlɪzəm/) is the whole of the biochemical processes responsible for the metabolic formation, breakdown, and interconversion of carbohydrates in living organisms.

Etymology

The term "carbohydrate metabolism" is derived from the Greek words "carbo" which means "carbon" and "hydrate" which means "water". "Metabolism" comes from the Greek word "metabole" which means "change".

Overview

Carbohydrates are central to many essential metabolic pathways. Plants synthesize carbohydrates from carbon dioxide and water through the process of photosynthesis, allowing them to store energy absorbed from the sunlight internally. When animals and fungi consume plants, they use cellular respiration to break down these carbohydrates to release the energy they contain.

Processes

Carbohydrate metabolism involves several processes:

• Glycolysis: The process of converting glucose into pyruvate and generating small amounts of ATP (energy) and NADH (reducing power). It is a central pathway that produces important precursor metabolites: six-carbon compounds of glucose-6P and fructose-6P and three-carbon compounds of glycerone-P, glyceraldehyde-3P, glycerate-3P, phosphoenolpyruvate, and pyruvate.

• Gluconeogenesis: The generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and glucogenic amino acids.

• Pentose phosphate pathway: A metabolic pathway parallel to glycolysis which generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-phosphate, the latter a precursor for the synthesis of nucleotides.

• Glycogenesis: The process of glycogen synthesis, in which glucose molecules are added to chains of glycogen for storage.

• Glycogenolysis: The breakdown of glycogen (n) to glucose-6-phosphate and glycogen (n-1). Its two primary functions are to make glucose available for muscle contraction and to maintain steady levels of glucose in the blood.

• Citric acid cycle: Also known as the Krebs cycle, it is a series of chemical reactions used by all aerobic organisms to release stored energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins into ATP and carbon dioxide.

Related Terms

• Glucose
• Fructose
• Galactose
• Glycogen
• Insulin
• Glucagon
• Pyruvate
• Lactate
• Glycerol
• Amino acids
• ATP
• NADH
• NADPH
• Carbon dioxide
• Water
• Photosynthesis
• Cellular respiration

External links

• Medical encyclopedia article on Carbohydrate metabolism
• Wikipedia's article - Carbohydrate metabolism

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