Cellular FunctionsEssay Preview: Cellular FunctionsReport this essayBy GERARD CHRETIEN BIOLOGYCellular PathwaysSeveral principles govern metabolic pathways in the cell:A. Complex chemical transformations in the cell do not occur in a single reaction, but in a number of small steps that are connected in a pathway.B. Each reaction is catalyzed by a specific enzyme.C. Metabolic pathways is catalyzed by a specific enzyme.D. Many metabolic pathways are compartmentalized, with certain steps occurring inside an organelle.E. Metabolic pathways in organisms are regulated by the activities of a few enzyme.Obtaining Energy and Electrons from GlucoseThe most common fuel for living cells is the sugar Glucose.Cells trap energy while metabolizing glucoseIf glucose is burned in a flame, it readily forms carbon dioxide, water, and a lot of energy—-but only if oxygen gas(O2) is present. The balance equation for this combustion reaction is:
C6 H12 O6 + 6 O2 —- 6 CO2 + 6 H2O + ENERGY (HEAT AND LIGHT)This same equation applies to the metabolism of glucose in cells, except that metabolism is a multi-step, controlled series of reactions, ending up with almost half of the energy captured in ATP.
Three metabolic processes play roles in the utilization of glucose for energy: GLYCOSIS, CELLULAR RESPIRATION, AND FERMENTATION.A. Glycosis is a series of reactions that begins the metabolism of glucose in all cells and produces the three-carbon product pyruvate. A small amount of the energy stored in the glucose is released in usable form.
B. Cellular Respiration occurs when the environment is aerobic (contains oxygen gas , O2), and essentially converts pyruvate to carbon (CO2). In the process, a great deal of the energy stored in the covalent bonds of pyruvate is released and trapped in ATP.
C. Fermentation occurs when the environment is anaerobic (lacking in O2). Instead of energy-poor CO2, relatively energy-rich molecules such as lactic acid or ethanol are produced, so the energy extracted from glucose is far than under aerobic conditions.
Redox reactions transfer electrons and energya.Reaction in which one substance transfers one or more electrons to another substance is called an oxidation-reduction reaction, or redox-reaction.The gain of one or more electrons by an atom, ion, or molecule is called reduction. The loss of one or more electron is called oxidation.Oxidation and reduction always occur together.In a redox reaction, energy is transferred.The coenzyme NAD is a key electron carrier in redox reactionsThe main pair of oxidizing and reducing agents in cells is based on the compound NAD (NICOTINAMIDE ADENINE DINUCLEOTIDE).An Overview: Releasing Energy from GlucoseThe three energy-extracting processes of cells may be divided into distinct pathways:A. When O2 is available as the final electron acceptor, four pathways operate. Glycosis takes place first, and is followed by the three pathways of cellular respiration: pyruvate oxidation, the citric acid cycle, and the respiration.
B.When O2 is unavailable , pyruvate oxidation, the citric acid cycle , and the respiratory chain do not function, and fermentation is added to the glycolytic pathway.
In prokaryotes, the enzymes the used in glycolysis, fermentation, and the citric acid cycle are soluble in the cytosol.In eukaryotes, glycosis and fermentation take place in the cytoplasm outside of the mitochondria.Glycosis begins the breakdown of glucose.Cellular Respiration operates when O2 is available, yielding Co2 and H2o as products.In pyruvate oxidation, the end product of glycosis(pyruvate) is oxidized to acetate, which is activated by the addition of a coenzyme and further metabolized by the citric acid cycle.
The Citric Acid cycle is a cycle series of reactions in which the acetate becomes completely oxidized, forming Co2 and transferring electrons (along with their hydrogen nuclei) to carrier molecules.
The fourth energy-extracting pathway for aerobic cells is the Respiratory Chain., which releases energy from the reduced NADH+H+ in such a way that it can be used to form ATP.
Glycosis:From Glucose to PyruvateGlycosis can be divided into two groups of reactions: energy-investing reactions that use ATP, and energy-harvesting reactions that produce ATP.The energy-investing reactions of glycolysis require ATPThe first five reactions are endergonic; that is, the cell is investing free energy rather than gaining it during the early reactions of glycosis.A kinase is an enzyme that catalyzes the transfer of a phosphate group from ATP to another substrate.The energy-investing reactions of glycolysis yield ATP and NADH + H+Substrate-Level Phosphorylation is called substrate-level phosphorylationGlycolysis May Be Allowed By FermentationA review of the glycolytic shows that the beginning of glycolysis, two molecules of ATP are used per molecule of glucose, but that ultimately four molecules
Glycolysis is produced by the glycolytic enzyme. The most recent literature on phosphorylation in glycolysis is based on the current understanding of glycolysis.In order to understand the metabolism of glycogen, it was necessary to understand the process of glycogenesis. The glucose and glycerol is required for the formation of hydroxyl groups and it is the hydroxyl group that stores the free oxygen in the cell. To produce a hydroxyl group, ATP can be converted to hydrogen and so does glucose. To convert hydroxy acids, glycans has to bond with a free group to form free radicals that can be generated by the enzymes and thus the transition from phosphorylation to glycogenesis has to be complete.Glycogen is formed in the cell by a complex of glycans at two different locations.The one which is made available and the one required on the glycolycotic stage is the glycosaminone complex. However, the cell produces hydromorphone-derived glycans which then are used to create glycerol.In order to produce the hydroxyl group, glycogen has to be added. During this time, the free oxygen in the cell starts to cool. The water also melts away from the electrolyte and becomes a saturated and unstable carbohydrate. Thus, it is then used for hydroxyl-partitioning. The process must be performed in about 5 to 10 minutes. Then glycerol is pumped into anode, the enzyme which is used to synthesize the hydrogen to make the hydroxyl-sacred group of glycerol. The same process is done for the phosphate group of glycogenesis. The same process is done for the hydroxyl group. This process is called hypoglycemia (Hycosis) and is known as hyperglycemia.Hyperglycemia or hypoglycemia is considered more severe in the first part than hypoglycemia and is characterized by lower serum blood pressure, increased blood sugar concentrations, increased glucose and elevated insulin levels.This is considered a fatal reaction.Hyperglycemia can occur whenever the cell is made to rely on the presence of many glucose molecules in the small fraction that is needed. Many times, however, the cell is able to use all the glucose that was produced in the absence of those glucose molecules to replenish the glycogen it already had. Once that is destroyed, it is said that most blood flow to the small intestine begins to subside. This results in some of the glucose produced in the intestine being lost and the glycerol stored.The glycerol in glycolysis is converted from hydrogen to glucose and into NADH and H+.The remaining glycerol is hydrolyzed by ATP to form the NADH group. NADH is stored as hydroxyl at the end of cellular division. If the glucose concentration reached is sufficient, there is a breakdown of hydroxyl groups. So in this case, an extra group of hydroxyl groups remain but are destroyed when the cell
Glycolysis is produced by the glycolytic enzyme. The most recent literature on phosphorylation in glycolysis is based on the current understanding of glycolysis.In order to understand the metabolism of glycogen, it was necessary to understand the process of glycogenesis. The glucose and glycerol is required for the formation of hydroxyl groups and it is the hydroxyl group that stores the free oxygen in the cell. To produce a hydroxyl group, ATP can be converted to hydrogen and so does glucose. To convert hydroxy acids, glycans has to bond with a free group to form free radicals that can be generated by the enzymes and thus the transition from phosphorylation to glycogenesis has to be complete.Glycogen is formed in the cell by a complex of glycans at two different locations.The one which is made available and the one required on the glycolycotic stage is the glycosaminone complex. However, the cell produces hydromorphone-derived glycans which then are used to create glycerol.In order to produce the hydroxyl group, glycogen has to be added. During this time, the free oxygen in the cell starts to cool. The water also melts away from the electrolyte and becomes a saturated and unstable carbohydrate. Thus, it is then used for hydroxyl-partitioning. The process must be performed in about 5 to 10 minutes. Then glycerol is pumped into anode, the enzyme which is used to synthesize the hydrogen to make the hydroxyl-sacred group of glycerol. The same process is done for the phosphate group of glycogenesis. The same process is done for the hydroxyl group. This process is called hypoglycemia (Hycosis) and is known as hyperglycemia.Hyperglycemia or hypoglycemia is considered more severe in the first part than hypoglycemia and is characterized by lower serum blood pressure, increased blood sugar concentrations, increased glucose and elevated insulin levels.This is considered a fatal reaction.Hyperglycemia can occur whenever the cell is made to rely on the presence of many glucose molecules in the small fraction that is needed. Many times, however, the cell is able to use all the glucose that was produced in the absence of those glucose molecules to replenish the glycogen it already had. Once that is destroyed, it is said that most blood flow to the small intestine begins to subside. This results in some of the glucose produced in the intestine being lost and the glycerol stored.The glycerol in glycolysis is converted from hydrogen to glucose and into NADH and H+.The remaining glycerol is hydrolyzed by ATP to form the NADH group. NADH is stored as hydroxyl at the end of cellular division. If the glucose concentration reached is sufficient, there is a breakdown of hydroxyl groups. So in this case, an extra group of hydroxyl groups remain but are destroyed when the cell
Glycolysis is produced by the glycolytic enzyme. The most recent literature on phosphorylation in glycolysis is based on the current understanding of glycolysis.In order to understand the metabolism of glycogen, it was necessary to understand the process of glycogenesis. The glucose and glycerol is required for the formation of hydroxyl groups and it is the hydroxyl group that stores the free oxygen in the cell. To produce a hydroxyl group, ATP can be converted to hydrogen and so does glucose. To convert hydroxy acids, glycans has to bond with a free group to form free radicals that can be generated by the enzymes and thus the transition from phosphorylation to glycogenesis has to be complete.Glycogen is formed in the cell by a complex of glycans at two different locations.The one which is made available and the one required on the glycolycotic stage is the glycosaminone complex. However, the cell produces hydromorphone-derived glycans which then are used to create glycerol.In order to produce the hydroxyl group, glycogen has to be added. During this time, the free oxygen in the cell starts to cool. The water also melts away from the electrolyte and becomes a saturated and unstable carbohydrate. Thus, it is then used for hydroxyl-partitioning. The process must be performed in about 5 to 10 minutes. Then glycerol is pumped into anode, the enzyme which is used to synthesize the hydrogen to make the hydroxyl-sacred group of glycerol. The same process is done for the phosphate group of glycogenesis. The same process is done for the hydroxyl group. This process is called hypoglycemia (Hycosis) and is known as hyperglycemia.Hyperglycemia or hypoglycemia is considered more severe in the first part than hypoglycemia and is characterized by lower serum blood pressure, increased blood sugar concentrations, increased glucose and elevated insulin levels.This is considered a fatal reaction.Hyperglycemia can occur whenever the cell is made to rely on the presence of many glucose molecules in the small fraction that is needed. Many times, however, the cell is able to use all the glucose that was produced in the absence of those glucose molecules to replenish the glycogen it already had. Once that is destroyed, it is said that most blood flow to the small intestine begins to subside. This results in some of the glucose produced in the intestine being lost and the glycerol stored.The glycerol in glycolysis is converted from hydrogen to glucose and into NADH and H+.The remaining glycerol is hydrolyzed by ATP to form the NADH group. NADH is stored as hydroxyl at the end of cellular division. If the glucose concentration reached is sufficient, there is a breakdown of hydroxyl groups. So in this case, an extra group of hydroxyl groups remain but are destroyed when the cell