Table of Contents
Introduction:
Glycolysis is the process by which glucose is broken down to produce energy. It produces two pyruvate molecules, ATP, NADH, and water. The process takes place in the cytoplasm of the cell and does not require oxygen. It occurs in both aerobic and anaerobic organisms.
Glycolysis is a major step in cellular respiration, which occurs in all living things. Glycolysis is followed by the Krebs cycle during aerobic breathing. In the absence of oxygen, cells produce small amounts of ATP as glycolysis is followed by fermentation.
This metabolic method was discovered by three German pharmacists – Gustav Embden, Otto Meyerhof, and Jakub Karol Parnas in the early 19th century and became known as the EMP pathway (Embden-Meyerhof-Parnas).
Glycolysis Pathway:
Glycolysis is a series of reactions that release energy from sugar by breaking it down into two carbon-three molecules called pyruvates. Glycolysis is an old metabolic process, which means it originated long ago and is found in most living organisms today.In animals that perform cellular respiration, glycolysis is the first stage of this process. However, glycolysis does not require oxygen, and many anaerobic organisms — non-oxygen-dependent organisms — also have this approach.
The glycolysis pathway occurs in the following stages:
Stage 1
- The phosphate group is added to glucose in the cell cytoplasm, by the action of the enzyme hexokinase.
- In this case, the phosphate group is transferred from ATP to glucose-producing glucose, 6-phosphate.
Stage 2
Glucose-6-phosphate is incorporated into fructose, 6-phosphate by the enzyme phosphoglucomutase.
Stage 3
Another ATP molecule transports a phosphate group to fructose 6-phosphate and converts it into fructose 1,6-bisphosphate by the action of the enzyme phosphofructokinase.
Stage 4
The enzyme aldolase converts fructose 1,6-bisphosphate into glyceraldehyde 3-phosphate and dihydroxyacetone phosphate, which are isomers to each other.
Step 5
Triose-phosphate isomerase converts dihydroxyacetone phosphate into glyceraldehyde 3-phosphate substrate in a subsequent step of glycolysis.
Step 6
This step deals with two reactions:
The enzyme glyceraldehyde 3-phosphate dehydrogenase transfers 1 hydrogen molecule from glyceraldehyde phosphate to its nicotinamide adenine dinucleotide NADH + H +.
Glyceraldehyde 3-phosphate dehydrogenase adds phosphate to oxidized glyceraldehyde phosphate to form 1,3-bisphosphoglycerate.
Step 7
Phosphate is transferred from 1,3-bisphosphoglycerate to ADP to form ATP with the help of phosphoglycerokinase. Thus two molecules of phosphoglycerate and ATP are found at the end of this reaction.
Step 8
The phosphate of both phosphoglycerate molecules is transported from the third to the second carbon to produce two 2-phosphoglycerate molecules with the enzyme phosphoglyceromutase.
Step 9
The enzyme removes the water molecule from 2-phosphoglycerate to form phosphoenolpyruvate.
Step 10
Phosphate from phosphoenolpyruvate is transferred to ADP to form pyruvate and ATP by pyruvate kinase action. Two molecules of pyruvate and ATP are available as final products.
Process of Glycolysis
The metabolic pathway of glycolysis involves the oxidative division of one glucose molecule into two pyruvates by taking a certain amount of ATP and NADH. Glycolysis is a common procedure that occurs in both aerobic and anaerobic respiration.
Glucose is the only source of energy for the brain, so for the brain to function properly the body must supply a sufficient amount of glucose to the brain through the blood. We can therefore say that glycolysis is an important process that takes place in the cell.
Glycolysis: Method Strength and Importance
Glycolysis occurs in both prokaryotes and eukaryotes. Although there are different processes occurring in the body, glycolysis is the most important as it produces the intermediate content needed for other metabolic processes. The process of glycolysis takes place in the cytosol and is a very important process in mitochondria-free organisms. The final product of glycolysis is pyruvate, which acts as a central site for various processes such as gluconeogenesis, fermentation, etc.
The glycolysis potential includes, from a glucose molecule, two glyceraldehyde 3-phosphate molecules are formed in the second phase of glycolysis in which two pyruvate molecules are obtained as the final products of glycolysis. The glycolysis potential is therefore calculated by considering two molecules of glyceraldehyde 3-phosphate.
Importance of Glycolysis:
- Glucose – 6 – p is a normal medium required for various metabolic reactions such as glycogen synthesis, HMP pathway, etc.
- Fructose – 6 – P is needed for glucosamine synthesis.
- In the HMP method of pentose synthesis, triose-like glyceraldehyde – 3 – P is used.
Strength of Anaerobic Glycolysis:
Anaerobic glycolysis occurs when there is no oxygen, during a lack of oxygen, and in the event of a great need for muscle strength, a form of anaerobic glycolysis occurs. As RBCs lack mitochondria, they gain energy from lactic acid fermentation. Another example is when anaerobic respiration occurs in the lens of the eye.
Two procedures occur under anaerobic glycolysis, namely:
- Lactic Acid fermentation: This process occurs when there is no oxygen in the muscles when lactate is converted to pyruvate with the help of an enzyme called lactate dehydrogenase.
- Ethanol Fermentation: In this process, glucose is converted into ethanol instead of pyruvate.
We can therefore say that the final product of anaerobic respiration is lactic acid or ethanol and ATP molecules.
Gluconeogenesis Significance:
Gluconeogenesis is a process that contains a series of 11 enzyme-catalyzed reactions. The pathway will begin in the liver or kidneys, in the mitochondria, or in the cytoplasm of those cells, depending on the substrate used.
The importance of gluconeogenesis is as follows:
- When a sufficient amount of carbohydrates is not found in the diet this process provides the necessary glucose.
- Through the process of glycogenolysis, glycogen stored in adipose tissue and skeletal muscle is converted into sugar.
- It is used to remove metabolic products from other tissues in the blood.
The potential for gluconeogenesis is six nucleotide triphosphate molecules are hydrolyzed to synthesize sugar from pyruvate in gluconeogenesis, while only two ATP molecules are produced in glycolysis to convert sugar into pyruvate.
Glycolysis is a very important process that takes place in the environment studied under Biology. We all know that living things need food to survive. All animals, whether carnivores or herbivores, get their food directly or indirectly from a diabetic plant. After taking glucose, the metabolic functions performed in the animal’s body are transformed into truly useful forms. By using the oxygen found in the respiratory system glucose is broken down into simpler forms. This cracking can also occur in the absence of oxygen called anaerobic glycolysis.
However, the most common type is aerobic breathing where there is oxygen and the use of ATP. This is the only way to have the power to do different things.
The glucose molecule contains six carbon atoms and 6 oxygen atoms and 12 hydrogen atoms. During the chemical breakdown of glucose in the pyruvate molecules are found. Several other molecules are also found in the glycolysis process which is also vital for the functioning of various metabolic functions in animals and in the human body. For example, fructose is needed for glucosamine, while glyceraldehyde is used for pentose synthesis.
Also read: Respiration: Exchange Gases
FAQs
Is there an evolutionary significance of Glycolysis?
Life on earth has evolved over millions of years through gradual evolution. The first living creatures on the planet were the rare living creatures known as eukaryotes. But it is only after the emergence of multicellular organisms such as prokaryotic microorganisms that the complexity of life begins to develop. In the oxygen-deprived atmosphere of the day, these ancient prokaryotes enhanced the Glycolysis process. This method of finding the energy to sustain the energy needs of living things was later transferred to other higher forms of life by evolution.
Q. What are the three main steps involved in Glycolysis?
Ans: The most important steps involved in glycolysis are:
- Glucose is trapped and inactive as it is the main ingredient.
- Three flexible carbon molecules are produced by the breakdown of carbon-six fructose.
- ATP is produced.
Q. What are the different types of Glycolysis?
Ans: There are 2 different types of glycolysis, namely:
- Aerobic breathing
- Anaerobic breathing
In aerobic conditions, pyruvate enters the citric acid cycle and undergoes oxidative phosphorylation leading to the production of a net of 32 ATP molecules. In anaerobic cases, pyruvate converts to lactate using anaerobic glycolysis.
