Why is glucose breakdown important

Carbohydrates are one of the major forms of energy for animals and plants. Plants build carbohydrates using light energy from the sun during the process of photosynthesis , while animals eat plants or other animals to obtain carbohydrates. Plants store carbohydrates in long polysaccharides chains called starch, while animals store carbohydrates as the molecule glycogen.

These large polysaccharides contain many chemical bonds and therefore store a lot of chemical energy. When these molecules are broken down during metabolism, the energy in the chemical bonds is released and can be harnessed for cellular processes. All living things use carbohydrates as a form of energy.

Both plants and animals like this squirrel use cellular respiration to derive energy from the organic molecules originally produced by plants. The metabolism of any monosaccharide simple sugar can produce energy for the cell to use. Excess carbohydrates are stored as starch in plants and as glycogen in animals, ready for metabolism if the energy demands of the organism suddenly increase.

When those energy demands increase, carbohydrates are broken down into constituent monosaccharides, which are then distributed to all the living cells of an organism. Glucose C 6 H 12 O 6 is a common example of the monosaccharides used for energy production.

Inside the cell, each sugar molecule is broken down through a complex series of chemical reactions. As chemical energy is released from the bonds in the monosaccharide, it is harnessed to synthesize high-energy adenosine triphosphate ATP molecules. ATP is the primary energy currency of all cells. Just as the dollar is used as currency to buy goods, cells use molecules of ATP to perform immediate work and power chemical reactions.

The breakdown of glucose during metabolism is call cellular respiration can be described by the equation:. Plants and some other types of organisms produce carbohydrates through the process called photosynthesis. During photosynthesis, plants convert light energy into chemical energy by building carbon dioxide gas molecules CO 2 into sugar molecules like glucose. Because this process involves building bonds to synthesize a large molecule, it requires an input of energy light to proceed.

The synthesis of glucose by photosynthesis is described by this equation notice that it is the reverse of the previous equation :. In plants, glucose is stored in the form of starch, which can be broken down back into glucose via cellular respiration in order to supply ATP.

These are the conditions under which most reactions are carried out in the laboratory. The system is usually open to the atmosphere constant pressure and the process is started and ended at room temperature after any heat that has been added or which was liberated by the reaction has dissipated. The importance of the Gibbs function can hardly be over-stated: it determines whether a given chemical change is thermodynamically possible.

Metabolic and genetic regulation of cardiac energy substrate preference. Kresge, N. Otto Fritz Meyerhof and the elucidation of the glycolytic pathway. Journal of Biological Chemisry , e3 Kroemer, G. Tumor cell metabolism: Cancer's Achilles' heel. Cancer Cell 13 , — Vander Heiden, M. Understanding the Warburg effect: The metabolic requirements of cell proliferation Science 22 , — Critical steps in cellular fatty acid uptake and utilization.

Molecular and Cellular Biochemistry , 9—15 What Is a Cell? Eukaryotic Cells. Cell Energy and Cell Functions.

Photosynthetic Cells. Cell Metabolism. The Origin of Mitochondria. Mitochondrial Fusion and Division. The Origin of Plastids. The Origins of Viruses. Discovery of the Giant Mimivirus. Volvox, Chlamydomonas, and the Evolution of Multicellularity. Yeast Fermentation and the Making of Beer and Wine. Dynamic Adaptation of Nutrient Utilization in Humans.

Nutrient Utilization in Humans: Metabolism Pathways. An Evolutionary Perspective on Amino Acids. Mitochondria and the Immune Response. Stem Cells in Plants and Animals. Promising Biofuel Resources: Lignocellulose and Algae. The Discovery of Lysosomes and Autophagy.

The Mystery of Vitamin C. Luz, Ph. Da Poian, Ph. Citation: El Bacha, T. Nature Education 3 9 Food in, energy out? Aa Aa Aa. Hormones Regulate Cell Metabolism. The Liver Supplies Blood Glucose. References and Recommended Reading Cahill, G. Annual Review of Nutrition 26 , 1—22 Iyer, A.

Nature Reviews Endocrinology 6 , 71—82 Kaelin, W. Journal of Biological Chemisry , e3 Kroemer, G. Cancer Cell 13 , — Vander Heiden, M. Understanding the Warburg effect: The metabolic requirements of cell proliferation Science 22 , — van der Vusse, G.

Article History Close. Share Cancel. Revoke Cancel. Keywords Keywords for this Article. Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel. This content is currently under construction. Explore This Subject. Topic rooms within Cell Origins and Metabolism Close. No topic rooms are there. Or Browse Visually.

Student Voices. Creature Cast. Simply Science. Green Screen. Green Science. Bio 2. The Success Code. Why Science Matters. The Beyond. Plant ChemCast. The process does not use oxygen and is, therefore, anaerobic. Glycolysis is the first of the main metabolic pathways of cellular respiration to produce energy in the form of ATP.

Through two distinct phases, the six-carbon ring of glucose is cleaved into two three-carbon sugars of pyruvate through a series of enzymatic reactions. The first phase of glycolysis requires energy, while the second phase completes the conversion to pyruvate and produces ATP and NADH for the cell to use for energy.

Overall, the process of glycolysis produces a net gain of two pyruvate molecules, two ATP molecules, and two NADH molecules for the cell to use for energy. Cellular Respiration : Glycolysis is the first pathway of cellular respiration that oxidizes glucose molecules. It is followed by the Krebs cycle and oxidative phosphorylation to produce ATP.

In the first half of glycolysis, energy in the form of two ATP molecules is required to transform glucose into two three-carbon molecules. In the first half of glycolysis, two adenosine triphosphate ATP molecules are used in the phosphorylation of glucose, which is then split into two three-carbon molecules as described in the following steps. The first half of glycolysis: investment : The first half of glycolysis uses two ATP molecules in the phosphorylation of glucose, which is then split into two three-carbon molecules.

Step 1. The first step in glycolysis is catalyzed by hexokinase, an enzyme with broad specificity that catalyzes the phosphorylation of six-carbon sugars.

Hexokinase phosphorylates glucose using ATP as the source of the phosphate, producing glucosephosphate, a more reactive form of glucose. This reaction prevents the phosphorylated glucose molecule from continuing to interact with the GLUT proteins. It can no longer leave the cell because the negatively-charged phosphate will not allow it to cross the hydrophobic interior of the plasma membrane.

Step 2. In the second step of glycolysis, an isomerase converts glucosephosphate into one of its isomers, fructosephosphate. An enzyme that catalyzes the conversion of a molecule into one of its isomers is an isomerase.

This change from phosphoglucose to phosphofructose allows the eventual split of the sugar into two three-carbon molecules. Step 3. The third step is the phosphorylation of fructosephosphate, catalyzed by the enzyme phosphofructokinase. A second ATP molecule donates a high-energy phosphate to fructosephosphate, producing fructose-1,6-bisphosphate. In this pathway, phosphofructokinase is a rate-limiting enzyme.

This is a type of end-product inhibition, since ATP is the end product of glucose catabolism. Step 4. The newly-added high-energy phosphates further destabilize fructose-1,6-bisphosphate. The fourth step in glycolysis employs an enzyme, aldolase, to cleave 1,6-bisphosphate into two three-carbon isomers: dihydroxyacetone-phosphate and glyceraldehydephosphate.

Step 5. In the fifth step, an isomerase transforms the dihydroxyacetone-phosphate into its isomer, glyceraldehydephosphate. Thus, the pathway will continue with two molecules of a single isomer.