10 Steps of Glycolysis

10 Steps of Glycolysis Glycolysis literally means splitting sugars and is the process of releasing energy within sugars. In glycolysis, glucose (a six-carbon sugar) is split into two molecules of the three-carbon sugar pyruvate. This multistep process yields two molecules of ATP (free energy containing molecule), two molecules of pyruvate, and two high energy electron carrying molecules of NADH. Key Takeaways: Glycolysis Glycolysis is the process of breaking down glucose into two molecules of pyruvate. It produces ATP and is the first stage of cellular respiration. Glycolysis can occur with or without oxygen. In the presence of oxygen, glycolysis is the first stage of cellular respiration. In the absence of oxygen, glycolysis allows cells to make small amounts of ATP through the process of fermentation. Glycolysis takes place in the cytosol of the cells cytoplasm. However, the next stage of cellular respiration, known as the citric acid cycle, occurs in the matrix of cell mitochondria. Below are the 10 steps of glycolysis. Step 1 The enzyme hexokinase phosphorylates - adds a phosphate group to - glucose in the cells cytoplasm. In the process, a phosphate group from ATP is transferred to glucose producing glucose 6-phosphate. The equation is: Glucose (CStep 2 The enzyme phosphoglucoisomerase converts glucose 6-phosphate into its isomer fructose 6-phosphate. Isomers have the same molecular formula, but the atoms of each molecule are arranged differently. The equation for this step is: Glucose 6-phosphate (CStep 3 The enzyme phosphofructokinase uses another ATP molecule to transfer a phosphate group to fructose 6-phosphate to form fructose 1, 6-bisphosphate. The equation is: Fructose 6-phosphate (CStep 4 The enzyme aldolase splits fructose 1, 6-bisphosphate into two sugars that are isomers of each other. These two sugars are dihydroxyacetone phosphate and glyceraldehyde phosphate. The equation is: Fructose 1, 6-bisphosphate (CStep 5 The enzyme triose phosphate isomerase rapidly inter-converts the molecules dihydroxyacetone phosphate and glyceraldehyde 3-phosphate. Glyceraldehyde 3-phosphate is removed as soon as it is formed to be used in the next step of glycolysis. The two equations for this step are: Dihydroxyacetone phosphate (CNet result for step Nos. 4 and 5: Step 6 The enzyme triose phosphate dehydrogenase serves two functions in this step. First, the enzyme transfers a hydrogen (H-) from glyceraldehyde phosphate to the oxidizing agent nicotinamide adenine dinucleotide (NAD) to form NADH. Next, triose phosphate dehydrogenase adds a phosphate (P) from the cytosol to the oxidized glyceraldehyde phosphate to form 1, 3-bisphosphoglycerate. This occurs for both molecules of glyceraldehyde 3-phosphate produced in step 5. The two equations for this step are: A. Triose phosphate dehydrogenase + 2 HB. Triose phosphate dehydrogenase + 2 P + 2 glyceraldehyde 3-phosphate (CStep 7 The enzyme phosphoglycerokinase transfers a P from 1,3-bisphosphoglycerate to a molecule of ADP to form ATP. This happens for each molecule of 1,3-bisphosphoglycerate. The process yields two 3-phosphoglycerate molecules and two ATP molecules. The equation is: 2 molecules of 1,3-bisphoshoglycerate (CStep 8 The enzyme phosphoglyceromutase relocates the P from 3-phosphoglycerate from the third carbon to the second carbon to form 2-phosphoglycerate. The equation is: 2 molecules of 3-Phosphoglycerate (CStep 9 The enzyme enolase removes a molecule of water from 2-phosphoglycerate to form phosphoenolpyruvate (PEP). This happens for each molecule of 2-phosphoglycerate. The equation is: 2 molecules of 2-Phosphoglycerate (CStep 10 The enzyme pyruvate kinase transfers a P from PEP to ADP to form pyruvate and ATP. This happens for each molecule of phosphoenolpyruvate. This reaction yields two molecules of pyruvate and two ATP molecules. The equation is: 2 molecules of phosphoenolpyruvate (CEnd Result MediaForMedica l /UIG / Getty Images A single glucose molecule in glycolysis produces a total of two molecules of pyruvate, two molecules of ATP, two molecules of NADH, and two molecules of water. Although two ATP molecules are used in step Nos. 1 through 3, two ATP molecules are generated in step No. 7 and two more in step No. 10. This gives a total of four ATP molecules produced. If you subtract the two ATP molecules used in step Nos. 1 through 3 from the four generated at the end of step No. 10, you end up with a net total of two ATP molecules produced.

Insectivores - Insectivora - The Animal Encyclopedia

Insectivores - Insectivora - The Animal Encyclopedia Insectivores (Insectivora) are a group of mammals that include hedgehogs, moonrats, shrews, and moles. Insectivores are generally small mammals with nocturnal habits. There are about 365 species of insectivores alive today. Most insectivores have small eyes and ears and a long snout. Some do not have visible ear flaps but have a keen sense of hearing. They have clawed toes on each foot, and the pattern and number of their teeth are rather primitive. Some insectivores such as otter-shrews and moonrats have a long body. Moles have a more cylindrical body, and hedgehogs have a round body. Some insectivores such as tree moles and shrews are adept tree climbers. Insectivores rely more on their sense of smell, hearing, and touch than their vision and some species of shrews can navigate their environment using echolocation. The bones in the inner ear of insectivores are different than other mammals. They lack an ossified temporal bone, and the tympanic membrane is attached to a bony tympanic ring while their middle ear is closed off by surrounding bones. Insectivores live in terrestrial habitats around the world. Additionally, some species of insectivores inhabit aquatic environments while others burrow. Moles spend most of their time below ground in their tunnels they excavate. Shrews generally live above ground and build burrows for shelter and sleeping. Some species live in boggy areas where rotting vegetation, rocks, and rotting logs are common. Other species inhabit arid regions including deserts. Moles and shrews are usually active throughout the year. Hedgehogs are easily recognized by their rotund shape and spines. Their spines consist of tough keratin and serve as a defense mechanism. When threatened, hedgehogs roll into a tight ball so their spines are exposed and their face and belly are protected. Hedgehogs are mostly nocturnal. As their name implies, insectivores feed on insects and other small invertebrates such as spiders and worms. The diet of insectivores is not restricted to invertebrates and also includes a wide variety of plants and animals. Water shrews feed on small fish, amphibians, and crustaceans while hedgehogs feed on birds eggs and small vertebrates. Many species of insectivores locate their prey using their keen sense of smell or by using their sense of touch. The star-nosed mole, for example, not only has a sharp sense of smell, but it also has a nose with many small and touch-sensitive tentacles that enable it to find and capture their prey. Classification Animals Chordates Mammals Insectivores There are four living subgroups of insectivores. These include the hedgehogs, moonrats, and gymnures (Erinaceidae); the shrews (Soricidae); the moles, tree moles and desmans (Talpidae); and the solenodons (Solenodontidae). Insectivores are thought to be most closely related to bats, hoofed mammals, and carnivores. The classification of insectivores is not well understood. Insectivores have a primitive mammalian body plan and are in many ways generic in their appearance. For this reason, insectivores have been classified in several other mammal groups in the past such as the tree shrews or elephant shrews. Additionally, some adaptations insectivores exhibit are convergent with the adaptations of other groups- a fact that further confuses the proper placement of insectivores within the mammals. Previous classification schemes once placed tree shrews and elephant shrews in the insectivores, but today they are classified in their own separate orders. It is possible that other animal groups such as golden moles may be removed from the insectivores as new information comes to light. Evolution Insectivores are considered to be among the most primitive groups of mammals. Some primitive traits insectivores still exhibit include a small brain and testes that do not descend into a scrotum.