Paper Topic:
Cellular Respiration and ATP
THE PATHWAYS CONNECTED WITH ENERGY FOOD AND UTILIZATION Introduction : Role of ATP in Supporting Energy to the Body When food is ingested , it is broken down into components and utilized in a specific manner in three major cellular pathways to provide energy for the cells and the body . Ultimately , these pathways involve the breakdown and utilization of food , the utilization of O2 and the production of CO2 , the generation and regeneration of ATP and the production of water . Therefore , these processes involve respiration as well as the breakdown and utilization of food
and oxygen . Three major pathways are involved : glycolysis which takes place in the cellular cytoplasm and breaks down glycogen and glucose from food , the Krebs Cycle which occurs in the mitochondrion and oxidative phosphorylation which occurs in the mitochondrion . These three pathways occur in two cellular locations . Glycolysis takes place in the cytoplasm and The Krebs Cycle and oxidative phosphorylation take place in the mitochondria . During these three pathways , there is a utilization and production of ATP that biochemists follow closely . It results in the net production of 36 molecules of ATP
To understand the entire process that illustrates how food is broken down and utilized in the body , it is instructive to follow a bolus , that is , food consumed , chewed and swallowed . Each step involves some aspect of digestion that breaks down complex sugar and protein molecules into smaller units . Proteins are broken down into peptides and amino acids while starches and other complex sugars are broken down into glucose . The glucose undergoes glycolysis in the cellular cytoplasm beginning with the enzyme hexokinase , and the entire process of glycolysis is controlled by the rate limiting enzyme phosphofructokinase (PFK . Kinase enzymes (enzymes that break down ATP are common all along the three pathways involved , glycolysis , the Krebs Cycle (also called the Citric Acid Cycle and the Tricaroxylic Acid Cycle ) and phosphorylative oxidation . Kinases are enzymes that break down or utilized ATP , ADP and AMP as their substrate or one of their substrates
Fiske and Subbarow discovered and characterized ATP in 1929 . At that time , the work of some demonstrated that the breakdown of ATP provided energy for muscle contraction , but other studies demonstrated that there was ATP synthesis during glycolysis and during electron transport . Although ATP is made throughout the cell , the cellular location of ATP synthesis varies with the biochemical pathways associated with ATP synthesis . Although one common pathway of ATP synthesis and breakdown is associated with the adenylate kinase reaction that forms two ADP molecules from ATP and AMP , studies in the late 1920s and beyond demonstrated that ATP synthesis was also associated with glycolysis and during electron transport . In 1949 , Kennedy and Lehninger demonstrated that ATP synthesis and the citric acid cycle occur in the mitochondria . We now recognize that ATP synthesis and breakdown can be associated with specific biochemical pathways in the cell cytoplasm and in the mitochondria . Some enzymes are sensitive to the ratio of ATP to AMP and to the presence of...
Not the Essay You're looking for? Get a custom essay (only for $12.99)
