The main difference between blood sugar and glucose is that blood sugar refers to the glucose carried to all of the cells in the body through the bloodstream, but glucose is a simple sugar, being the most abundant monosaccharide. Furthermore, blood sugar is the most important molecule in energy production through cellular respiration. Meanwhile, photosynthesis in plants is the biochemical reaction that synthesizes glucose, which is then stored in the form of starch in plants and glycogen in animals.
Blood sugar and glucose are two forms of one of the simplest and most important types of monosaccharides in both animals and plants. Also, their main function is to serve as the main source of energy in cellular respiration.
Key Areas Covered
1. What is Blood Sugar
– Definition, Features, Importance
2. What is Glucose
– Definition, Features, Importance
3. What are the Similarities Between Blood Sugar and Glucose
– Outline of Common Features
4. What is the Difference Between Blood Sugar and Glucose
– Comparison of Key Differences
Key Terms
Blood Sugar, Cellular Respiration, Glucagon, Glucose, Photosynthesis, Starch
What is Blood Sugar
Blood sugar or blood glucose is the glucose present in the bloodstream of animals. Its primary function is to enter the metabolizing cells of the body to be used as a source of energy. That is; glucose takes part in the cellular respiration, producing approximately 38 ATPs per molecule. However, animals are typically heterotrophs, and hence, they do not produce glucose inside their body. Therefore, dietary carbohydrates serve as the main source of glucose in the animal body. In this process, the digestive system is responsible for the breakdown of the carbohydrates in the diet into glucose and other minor types of monosaccharides.
Figure 1: Idealized Curves of Human Blood Glucose and Insulin Concentrations During the Course of a Day Containing Three Meals
Furthermore, the blood sugar level is the concentration of glucose in the blood at a particular moment. Approximately, 4 g of glucose is present in the blood of 70 kg human. However, in order to maintain the metabolic homeostasis, blood sugar level is highly regulated by the action of two hormones; the insulin and glucagon. Here, insulin reduces the high levels of glucose into normal by storing glucose in the form of glycogen in liver cells and skeletal cells. Conversely, glucagon increases the low levels of glucose into normal at the expense of glucagon stores in skeletal muscles and liver cells. Importantly, higher levels of glucose in the blood cause hyperglycemia, and persistent hyperglycemia results in diabetes Mellitus.
What is Glucose
Glucose is the simplest and the most common form of monosaccharide in both plants and animals. Furthermore, all living organisms use glucose as the main fuel of their cellular respiration. However, plants, being autotrophs, undergo photosynthesis to synthesize glucose. And, they store excess glucose in the form of starch and amylopectin. Also, plants produce one of the major structural polysaccharides, cellulose by using glucose as the monomer. But, heterotrophs, such as animals use the glucose produced by plants.
Figure 2: Isomeric Forms of Glucose
Moreover, glucose in nature occurs in two forms of stereoisomers; D-glucose and L-glucose, which are enantiomers of each other. Importantly, D-glucose or dextrose is the major form in nature, while L-glucose occurs desultory. Also, glucose occurs in two forms of structural isomers; open-chain form and cyclic form. Here, the latter is the result of an intramolecular reaction between the aldehyde C atom and C-5 hydroxyl group to form an intramolecular hemiacetal. Generally, in a solution, the cyclic form is the predominant structure of the glucose.
Similarities Between Blood Sugar and Glucose
- Blood sugar and glucose are two forms of one of the simplest and most important types of carbohydrates in both animals and plants.
- Their molecular formula is C6H12O6, which is a monosaccharide synthesized by photosynthesis in plants.
- Their main function is to serve as the main source of energy in the process of cellular respiration.
- Other than that, they serve as a storage molecule; starch in plants and glucagon in animals.
What is the Difference Between Blood Sugar and Glucose
Definition
Blood sugar refers to the main sugar found in the blood of humans and other animals, coming through the diet and serving as the main source of energy. Glucose refers to a simple sugar important as the main energy source in living organisms and is a component of many carbohydrates.
Occurrence
Blood sugar only occurs in the blood of animals. But glucose, in animals, occurs in the blood and inside cells, and in plants, it occurs inside the cells.
Significance
Blood sugar is the transport form of glucose in the body through the bloodstream, while glucose is a simple sugar, being the most abundant monosaccharide.
Roles
Blood sugar is important in energy production through cellular respiration. But, glucose, produced by photosynthesis in plants, is stored in the form of starch in plants and glycogen in animals.
Effect of them in Higher Levels
High levels of blood sugar levels result in hyperglycemia as well as diabetes mellitus, which is the persistent hyperglycemia. On the other hand, high levels of glucose, by serving as a monomer, lead to the synthesis of the common forms of polymers, such as cellulose and starch in plants and glucagon in animals.
Conclusion
Glucose is the simplest and the most common monosaccharide in both plants and animals. In general, plants synthesize glucose through photosynthesis and store them in the form of starch, which is then used in cellular respiration. Blood sugar is a form of glucose, circulating in the bloodstream of animals. Its main function is to supply glucose for the cells in metabolizing tissues of the body. Thereby, glucose serves as the main source of energy for cellular respiration. Furthermore, excess glucose is stored in the form of glycogen in animals. Apart from that, glucose serves as the precursor for cellulose and many other carbohydrates. Hence, the main difference between blood sugar and glucose is their occurrence and importance.
References:
1. DerSarkissian, Carol. “Blood Glucose (Blood Sugar): How It’s Made, How It’s Used, Healthy Levels.” WebMD, WebMD, 9 Aug. 2018, Available Here.
Image Courtesy:
1. “Suckale08 fig3 glucose insulin day” By Jakob Suckale, Michele Solimena – Solimena Lab and Review Suckale Solimena 2008 Frontiers in Bioscience, preprint PDF from Nature Precedings, original data: Daly et al. 1998 PMID:18508724 (CC BY 3.0) via Commons Wikimedia
2. “DL-Glucose” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
Leave a Reply