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Glucose - Meaning, Definition, History, Properties, FAQs

Glucose - Meaning, Definition, History, Properties, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:34 PM IST

What is Glucose?

Glucose Definition: Glucose formula is C6H12O6 chemical name is glucose. One of the most abundant monosaccharides, glucose belongs to the carbohydrate subcategory. The most abundant carbohydrate in the world, glucose is made by plants and most algae using sunlight to make it from water and carbon dioxide, which is used to make cellulose in their cell walls.

This Story also Contains
  1. What is Glucose?
  2. History of Glucose
  3. Chemical properties
  4. An overview of the nomenclature and structure
  5. Properties of Glucose

All organisms derive most of their energy from glucose in the process of metabolism. In plants, glucose is stored as starch and amylopectin, while in animals it is stored as glycogen. Animals have blood sugar that is made up of glucose.

It is the naturally occurring form of glucose, d-glucose, which is of lesser importance than the synthetic form l-glucose. There are six carbon atoms in glucose and therefore it is an aldohexose, not a monosaccharide. There are two types of glucose molecules: open-chain (acyclic) and ring (cyclic). Fruits and other parts of plants naturally contain glucose, and most plants store it in their free state. Glycogenolysis occurs in animals when glycogen is broken down. Among the safest and most effective medicines needed in a health system, glucose is a member of the World Health Organization's List of Essential Medicines. Combining it with sodium chloride also makes the list.

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History of Glucose

The German chemist Andreas Margraves isolated glucose from raisins for the first time in 1747. The distinction between grape sugar and cane sugar (sucrose) was made by Johann Tobias Levitz in 1792. Chemical literature has used the term glucose, which was coined in 1838 by Jean Baptiste Dumas. Aqueous solutions of glucose are polarized in the right direction in an aqueous solution of dextrose (from Latin dexter = right). In contrast, linearly polarized light is turned to the right by d-fructose (a ketohexose) and l-glucose. Chemical name of glucose is D-glucose.

A correct understanding of glucose provided a significant advance in the understanding of organic chemistry since glucose is a basic necessity for many organisms. As a result of Emil Fischer's investigations, who received the 1902 Nobel Prize in Chemistry for his findings, these notions were understood largely. Using Can't Hoff's theory of asymmetrical carbon atoms, Fischer correctly predicted all the possible isomers of sugars between 1891 and 1894. These compounds were originally used to name natural substances. Due to systematic nomenclatures, which take into account absolute stereochemistry (such as the Fischer nomenclature and D/L nomenclature), the two enantiomers have been given the same name.

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Chemical properties

Water and acetic acid display high solubility for glucose solids, but methanol and ethanol exhibit poor solubility. Hexose, with its six carbons, is one of the monosaccharides, a subgroup of sugars. Among the sixteen stereoisomers of aldohexose, d-glucose is one. Nature has both d-glucose and l-glucose, but the l-isomer, l-glucose, does not occur. The chemical process of hydrolysis is used to obtain glucose from carbohydrates like milk sugar (lactose), cane sugar (sucrose), maltose, cellulose, glycogen, etc.

Commercially, dextrose is manufactured from corn starch in the US and Japan, from potato and wheat starch in Europe, and from tapioca starch in tropical areas. During the manufacturing process, pressurized steam is used in a jet that hydrolyses the material at a controlled pH, followed by further enzymatic depolymerization. Honey is primarily composed of unbonded glucose. The glucose molecules are colourless and easily soluble in water, acetic acid, and several other solvents. Methanol and ethanol are only sparingly soluble in these compounds.

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An overview of the nomenclature and structure

A monohydrate of glucose with a closed pyran ring (dextrose hydrate) is usually present in solid form. It is present in aqueous solution as an open-chain to a small extent which interconverts primarily (see mutation). Crystallization of the three known forms: 5-glucopyranose, 5-glucopyranose, and 5-glucopyranose hydrate is possible from aqueous solutions. A building block for complex polysaccharides such as starch, amylopectin, glycogen, and cellulose, glucose is a disaccharide found in lactose and sucrose (cane or beet sugar). It has been determined that glucose has a glass transition temperature of 31 °C and the Gordon-Taylor constant (a constant set up through experiment to predict a mixture's glass transition temperature for different mass fractions of two substances) is 0.92.

Glucose

NCERT Chemistry Notes:

Glucose

Properties of Glucose

C6H12O6

Glucose

Molecular Weight/ Molar Mass

180.16 g/mol

Density

1.54 g/cm³

Simple sugar

Monosaccharide

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Frequently Asked Questions (FAQs)

1. 1. What are the Different Forms of Glucose Structure?

  1. The formula for open-chain transactions

  2. Arrangement

  3. An example of a cyclic structure

  4. HAWTHORNE REPRESENTATION

2. 2. How does the empirical formula for glucose work?

This formula is defined as the ratio of subscripts of the smallest whole number of elements present in the compound and is the simplest possible formula for the compound. The simplest formula also goes by that name.

a)  A compound’s empirical formula is its formula written with the smallest integer subscript.

3. 3. What is the molar mass of glucose? What is the molecular formula of glucose?



C = 12

     


       H = 1



            O = 16



∴ The molar mass of the glucose is



⇒ 12 x 6 + 1 x 12 + 16 x 6



⇒ 72 + 12 + 96



= 180



The molecular formula of glucose is C6H12O6.

4. 4. What are uses of glucose?

There is only one type of monosaccharide in it. Almost all carbohydrates, like starch and table sugar, glucose contains this. In addition to blood sugar, grape sugar is also known. Having six members, it is a pyranose ring structure is formed. Aldohexose is what it is. The body uses it as its primary and preferred energy source. Glucose is found in starch.

5. 5. Fructose: what is it?

There is only one type of monosaccharide in it. It can be found in vegetables and fruits. The glycemic index of fructose is lower than that of glucose. Glucose is seven times faster at binding to cellular proteins than fructose. D-Fructose and fructose are both terms for fructose. The ketone group makes it functional. Liver enzymes metabolize it mainly. It cannot be found in starch.

6. How does glucose contribute to the structure and function of nucleic acids?
Glucose plays an indirect role in nucleic acid structure and function. Through the pentose phosphate pathway, glucose can be converted to ribose-5-phosphate, which is a precursor for the synthesis of nucleotides. These nucleotides are the building blocks of DNA and RNA, crucial for genetic information storage and protein synthesis.
7. How does glucose concentration affect enzyme activity in biological systems?
Glucose concentration can affect enzyme activity in several ways. Some enzymes, like hexokinase, which catalyzes the first step of glycolysis, are regulated by glucose levels. High glucose concentrations can also lead to non-enzymatic glycation of proteins, potentially altering their structure and function. Additionally, extreme glucose concentrations can affect the osmotic environment, indirectly impacting enzyme activity.
8. How does glucose cross cell membranes?
Glucose crosses cell membranes through facilitated diffusion using specific transport proteins called glucose transporters (GLUTs). These proteins allow glucose to move down its concentration gradient without using energy. In some tissues, like the small intestine and kidneys, glucose can also be transported against its concentration gradient using sodium-glucose cotransporters (SGLTs), which require energy.
9. What is the role of glucose in the production of ATP through oxidative phosphorylation?
Glucose is the starting point for ATP production through oxidative phosphorylation. It's first broken down through glycolysis and the citric acid cycle, producing electron carriers (NADH and FADH2). These carriers donate electrons to the electron transport chain in the mitochondria, creating a proton gradient. This gradient drives ATP synthase to produce ATP, the cell's energy currency, through a process called chemiosmosis.
10. What is the significance of glucose in the production of vitamin C in animals?
Most animals can synthesize vitamin C (ascorbic acid) from glucose through a series of enzyme-catalyzed steps. However, humans and some other primates lack the enzyme L-gulonolactone oxidase, which is necessary for the final step in this pathway. As a result, humans must obtain vitamin C from their diet, while most other animals can produce it internally from glucose.
11. What is the difference between reducing and non-reducing sugars, and where does glucose fit in?
Reducing sugars have a free aldehyde or ketone group that can act as a reducing agent in certain chemical reactions. Glucose is a reducing sugar because it has a free aldehyde group when in its open-chain form. Non-reducing sugars, like sucrose, don't have this free group. This property is important in various chemical tests and reactions, including the formation of AGEs.
12. How do plants produce glucose?
Plants produce glucose through photosynthesis, a process that uses sunlight, carbon dioxide, and water. In the chloroplasts of plant cells, light energy is captured and used to convert CO2 and H2O into glucose and oxygen. This process is crucial for life on Earth, as it provides energy for plants and produces oxygen as a byproduct.
13. How does glucose contribute to the Maillard reaction in cooking?
The Maillard reaction is a chemical reaction between amino acids and reducing sugars, like glucose, that occurs when food is heated. This reaction produces brown colors and complex flavors in cooked foods. It's responsible for the browning of bread when toasted, the flavor of roasted coffee, and the crust on seared meats.
14. How does the body store excess glucose?
Excess glucose is stored in two main forms: glycogen and fat. In the liver and muscles, glucose is converted to glycogen through a process called glycogenesis. When glycogen storage is full, excess glucose is converted to fat (triglycerides) in a process called lipogenesis, which occurs mainly in the liver and adipose tissue.
15. What is the role of glucose in fermentation?
In fermentation, glucose serves as the primary substrate for microorganisms like yeast. These organisms break down glucose in the absence of oxygen to produce energy, along with byproducts like ethanol (in alcoholic fermentation) or lactic acid (in lactic acid fermentation). This process is crucial in the production of bread, beer, wine, and many other fermented foods.
16. What is the difference between α-glucose and β-glucose?
α-glucose and β-glucose are structural isomers that differ in the orientation of the hydroxyl group on carbon-1. In α-glucose, the -OH group is below the plane of the ring, while in β-glucose, it's above the plane. This small difference affects how glucose molecules link together to form larger carbohydrates like starch (α-linkages) or cellulose (β-linkages).
17. What is the role of glucose in cellular respiration?
Glucose is the primary substrate for cellular respiration, a process that breaks down glucose to produce ATP (adenosine triphosphate), the energy currency of cells. This process occurs in three main stages: glycolysis, the citric acid cycle, and the electron transport chain, ultimately converting the chemical energy in glucose into a usable form for cellular functions.
18. What is the difference between glucose and fructose?
Glucose and fructose are both monosaccharides with the same chemical formula (C6H12O6), but they have different structures. Glucose has a six-membered ring structure, while fructose has a five-membered ring. Fructose is sweeter than glucose and is metabolized differently in the body, primarily in the liver.
19. How does glucose contribute to the formation of advanced glycation end-products (AGEs)?
Glucose can react non-enzymatically with proteins in a process called glycation. Over time, these glycated proteins can form advanced glycation end-products (AGEs). AGEs accumulate in tissues as we age and are associated with various age-related diseases and complications of diabetes, such as cardiovascular disease and kidney problems.
20. How does the structure of glucose contribute to its function?
Glucose has a ring structure with multiple hydroxyl (-OH) groups. This structure allows glucose to form hydrogen bonds with water, making it soluble and easily transportable in the bloodstream. The arrangement of atoms also enables glucose to be quickly broken down for energy or linked together to form larger molecules like starch or cellulose.
21. What is glucose and why is it important?
Glucose is a simple sugar (monosaccharide) with the chemical formula C6H12O6. It's important because it's the primary source of energy for living organisms, serving as fuel for cellular respiration. Glucose is also a building block for more complex carbohydrates and plays a crucial role in various metabolic processes.
22. What is the relationship between glucose and diabetes?
Diabetes is a metabolic disorder characterized by high blood glucose levels. In Type 1 diabetes, the body doesn't produce enough insulin to regulate glucose. In Type 2 diabetes, cells become resistant to insulin's effects. Both types result in elevated blood glucose, which can lead to various health complications if not managed properly.
23. What is gluconeogenesis and why is it important?
Gluconeogenesis is the metabolic pathway that produces glucose from non-carbohydrate precursors like amino acids, lactate, and glycerol. This process is crucial for maintaining blood glucose levels during fasting or prolonged exercise when glucose stores are depleted. It primarily occurs in the liver and, to a lesser extent, in the kidneys.
24. How is blood glucose level regulated in the human body?
Blood glucose levels are primarily regulated by two hormones: insulin and glucagon. Insulin, produced by the pancreas, lowers blood glucose by promoting its uptake and storage in cells. Glucagon, also produced by the pancreas, raises blood glucose by stimulating the breakdown of stored glycogen in the liver. This balance helps maintain stable blood sugar levels.
25. What is the significance of the glycemic index?
The glycemic index (GI) is a measure of how quickly a food containing carbohydrates raises blood glucose levels. Foods with a high GI cause a rapid spike in blood sugar, while low GI foods result in a more gradual increase. Understanding the GI can help in managing blood sugar levels, particularly for people with diabetes or those trying to control their weight.
26. How does glucose concentration affect the growth of microorganisms?
Glucose concentration significantly influences microbial growth. Most microorganisms prefer glucose as an energy source due to its easy metabolization. At optimal concentrations, glucose promotes rapid growth. However, very high glucose concentrations can inhibit growth through osmotic stress or catabolite repression, where the presence of glucose suppresses the expression of enzymes needed to metabolize other sugars. Conversely, low glucose levels can limit growth and trigger stress responses in microorganisms.
27. How does glucose concentration affect osmosis in cells?
Glucose concentration plays a significant role in osmosis, the movement of water across cell membranes. If the glucose concentration outside a cell is higher than inside (hypertonic solution), water will move out of the cell, causing it to shrink. Conversely, if the external glucose concentration is lower (hypotonic solution), water will move into the cell, potentially causing it to burst if not regulated.
28. How does the body maintain glucose homeostasis during fasting?
During fasting, the body maintains glucose homeostasis through several mechanisms. Initially, it breaks down stored glycogen (glycogenolysis). As fasting continues, the body shifts to gluconeogenesis to produce glucose from non-carbohydrate sources. Hormones like glucagon and cortisol increase to promote these processes, while insulin levels decrease. The body also starts using alternative fuel sources like ketones to spare glucose for essential organs like the brain.
29. What is the role of glucose in the production of other monosaccharides?
Glucose serves as a precursor for the synthesis of other monosaccharides through various metabolic pathways. For example, glucose can be converted to fructose through the polyol pathway, and to galactose through the Leloir pathway. These conversions are important for producing sugars needed for specific cellular functions or for incorporation into more complex carbohydrates.
30. How does glucose contribute to the formation of glycoproteins and proteoglycans?
Glucose is a key component in the synthesis of glycoproteins and proteoglycans. It can be converted to other sugars like mannose, fucose, and N-acetylglucosamine, which are then used to form the carbohydrate chains attached to proteins in glycoproteins. Similarly, glucose derivatives are used in the formation of glycosaminoglycans, the carbohydrate components of proteoglycans. These molecules play crucial roles in cell signaling, immune function, and structural support in tissues.
31. What is the relationship between glucose and insulin resistance?
Insulin resistance occurs when cells in the body become less responsive to insulin, the hormone that facilitates glucose uptake. As a result, more insulin is needed to maintain normal blood glucose levels. Chronic high blood glucose levels can contribute to insulin resistance by causing cells to reduce the number of insulin receptors on their surface. This creates a vicious cycle where higher insulin levels are needed to manage blood glucose, potentially leading to Type 2 diabetes if not addressed.
32. How does glucose affect gene expression?
Glucose can influence gene expression through various mechanisms. High glucose levels can activate transcription factors like ChREBP (Carbohydrate-responsive element-binding protein), which regulates genes involved in glucose metabolism and lipogenesis. Glucose also affects the expression of genes related to insulin signaling and glucose transport. Additionally, glucose-derived metabolites can modify histones and DNA, leading to epigenetic changes that alter gene expression patterns.
33. What is the role of glucose in the production of dental plaque?
Glucose plays a significant role in the formation of dental plaque. Oral bacteria, particularly Streptococcus mutans, metabolize glucose and other sugars to produce acid as a byproduct. This acid lowers the pH in the mouth, promoting tooth demineralization. Additionally, some bacteria use glucose to produce sticky extracellular polysaccharides that help them adhere to teeth and form plaque, contributing to tooth decay and gum disease.
34. How does glucose contribute to the browning of fruits and vegetables?
Glucose contributes to the browning of fruits and vegetables through enzymatic browning. When fruits or vegetables are cut or bruised, cellular compartments are disrupted, allowing polyphenol oxidase enzymes to come into contact with phenolic compounds and oxygen. This reaction produces melanin pigments, causing browning. While glucose itself isn't directly involved in this reaction, it can contribute to non-enzymatic browning (Maillard reaction) during cooking or long-term storage.
35. What is the significance of glucose in cancer metabolism?
Glucose plays a crucial role in cancer metabolism. Many cancer cells exhibit increased glucose uptake and fermentation of glucose to lactate, even in the presence of oxygen, a phenomenon known as the Warburg effect. This altered metabolism supports rapid proliferation and survival in the tumor microenvironment. Understanding this unique glucose metabolism in cancer cells has led to diagnostic tools like PET scans and potential therapeutic targets for cancer treatment.
36. How does glucose affect wound healing?
Glucose is essential for wound healing as it provides energy for cellular processes involved in tissue repair. However, both high and low glucose levels can impair wound healing. Hyperglycemia (high blood glucose) can lead to impaired immune function, increased inflammation, and delayed wound closure. Conversely, hypoglycemia (low blood glucose) can slow healing by depriving cells of necessary energy. Maintaining optimal glucose levels is crucial for efficient wound healing.
37. What is the role of glucose in the production of neurotransmitters?
Glucose serves as a precursor for the synthesis of several neurotransmitters. It's particularly important for the production of acetylcholine, as glucose metabolism provides the acetyl-CoA needed for its synthesis. Glucose also indirectly supports the production of other neurotransmitters by providing energy for their synthesis and the maintenance of neuron function. Additionally, glucose levels can influence the release and reuptake of certain neurotransmitters, affecting neural signaling.
38. How does glucose contribute to the formation of glycated hemoglobin (HbA1c)?
Glycated hemoglobin (HbA1c) forms when glucose in the bloodstream attaches to hemoglobin molecules in red blood cells. This non-enzymatic glycation occurs continuously over the lifespan of the red blood cell (about 120 days). The amount of HbA1c formed is proportional to the average blood glucose concentration over this period, making it a useful marker for long-term blood glucose control in diabetes management.
39. What is the relationship between glucose and the production of reactive oxygen species (ROS)?
Glucose metabolism can lead to the production of reactive oxygen species (ROS) through several pathways. In the electron transport chain, high glucose flux can increase electron leak, leading to superoxide formation. Additionally, glucose can auto-oxidize in the presence of transition metals, directly producing ROS. Chronic high glucose levels can also lead to increased ROS production through the polyol pathway and advanced glycation end-product (AGE) formation, contributing to oxidative stress and cellular damage.
40. How does glucose affect osmolality in body fluids?
Glucose significantly contributes to the osmolality of body fluids, particularly blood plasma. As a solute, glucose affects the concentration of dissolved particles in the fluid, influencing osmotic pressure. In conditions like diabetes, where blood glucose levels are elevated, the increased osmolality can lead to symptoms like excessive thirst and frequent urination as the body attempts to dilute the blood and excrete excess glucose.
41. What is the role of glucose in the production of milk in mammals?
Glucose plays a crucial role in milk production in mammals. It serves as the primary precursor for lactose, the main carbohydrate in milk. In the mammary glands, glucose is converted to galactose, which then combines with another glucose molecule to form lactose. Glucose is also important for providing energy to the mammary gland cells for milk synthesis and as a precursor for other milk components like fatty acids.
42. What is the significance of glucose in the production of biofuels?
Glucose is a key component in the production of many biofuels. In ethanol production, glucose derived from corn starch or cellulose is fermented by yeast to produce ethanol. For biodiesel, glucose can be used to cultivate algae or other microorganisms that produce oils suitable for biodiesel production. Additionally, research is ongoing into converting glucose directly into hydrocarbon fuels through metabolic engineering of microorganisms.
43. How does glucose affect protein glycation in aging?
Glucose contributes to protein glycation, a process where glucose molecules attach to proteins without enzymatic control. This leads to the formation of advanced glycation end-products (AGEs). As we age, AGEs accumulate in tissues, contributing to the stiffening of collagen, decreased elasticity of blood vessels, and other age-related changes. Chronic high blood glucose levels, as seen in diabetes, accelerate this process, potentially speeding up certain aspects of aging.
44. What is the role of glucose in maintaining the blood-brain barrier?
Glucose plays a crucial role in maintaining the blood-brain barrier (BBB). The endothelial cells that form the BB

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Question : The first step in the process of nutrition is the breakdown of glucose into a three-carbon molecule called ______.

Option 1: pyruvate

Option 2: propanol

Option 3: propane

Option 4: methanol

Correct Answer: pyruvate


Solution : The correct option is pyruvate.

Glycolysis is the process of breaking glucose molecules to generate energy. In this process, the glucose is broken down to create pyruvate in a cell's cytoplasm. The breakdown of one glucose molecule into two pyruvate molecules results in the production of additional energy in one of two ways. In the presence of oxygen (aerobic respiration), pyruvic acid provides energy to living cells through the citric acid cycle, also referred to as the Krebs cycle. In the absence of oxygen, it ferments to form lactic acid.

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Question : Which one of the following is commonly used for pulp bleaching in the paper industry?

Option 1: Mild sulphuric acid

Option 2: Glucose isomerase

Option 3: Hydrogen peroxide

Option 4: Iodine and water

Correct Answer: Hydrogen peroxide


Solution : The correct option is Hydrogen peroxide.

In the paper industry, hydrogen peroxide (H2O2) is often used for pulp bleaching. It is a non-toxic bleaching chemical that aids in the removal of colour, and residual lignin from the wood pulp during the papermaking process. In comparison to other chemical agents, hydrogen peroxide degrades into water, and oxygen, making it a safer and more sustainable alternative for pulp bleaching.

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