Many diseases and disorders are caused by defects in the molecular level of cells and not just having to do with nutrition or other extrinsic factors ,in this report ,we will specifically look at enzymes and their key role in energy production and the cycles and series of activities that make it possible for the human to function properly .
Enzymes have four basic characteristics .They do not make a reaction occur that would not occur on its own, they just enhance and make it happen quicker. The enzyme will not be changed by the reaction, it may be changed during the process, but the end product will leave the enzyme as it was when it started. Enyzmes can be used repeatedly. Enyzmes have specific substances in our bodies, so if enzymes don’t work properly, metabolism will not work properly. Enzymes do their work as catalyst by speeding up the process to improve performance. They lessen the activation energy making producing products easier .Enzymes act on specific substances in our bodies. The enzymes will fit into the substance or substrate like a lock and key .Once it is with its certain substrate, it acts like a key and it unlocks the substrate and the substrate can do what it needs to do and then the enzyme will releases from it and is not changed ,then it moves on to another substance. Heredity Fructose Intolerance is a condition that can be passed down through families ,in HFI,two copies of an abnormal gene are present ,thus making it an auto recessive disorder, and frequently it is seen in person without a history of the disorder .
HFI is a condition that affects fructose metabolism ,basically the amount of Aldolase B’s substrate ,F1P ,changes when Aldolase B is deficient or doesn’t work at all. People that have this disorder do not have any symptoms if they do not ingest any fructose ,whether orally or by IV .F1P is a product of fructokinase and substrate for Aldolase B ,when Aldolase B is not available ,we start to see symptoms of HFI .Aldolase B is only seen in the kidney,liver,and small intestines. An excellent way to see enzymatic roles in our bodies is by studying how Fructose is metabolized in our liver .It is a multiply step, complex process .The first step is the conversion of fructose to fructose 1-phosphate by fructokinase ,which causes the fructose to become trapped in the liver .Then,Fructose-1-phosphate undergoes the chemical reaction called hydrolysis by fructose-1-phosphate aldolase (aldolase B) to form dihydroxyacetone phosphate (DHAP) and glyceraldehyde.
This usage of fructose leads to either glycolysis for the production of ATP or gluconeogenesis.Sanders, J. (2013) When fructose is taken into the body it is phosphorylated by fructokinase to make fructose 1 –phosphate , Aldolase B then impels F1P breakdown into glyceraldehyde and DHAP,that are used to go on to make ATP through glycolysis or to be used for storage through gluconeogenesis(glycolysis in reverse) .Fructose 1 Phosphate is a product and substrate but also a signal and it send out an alert for high blood sugar and will send signals to tell glucokinase to come out of the nucleus and into the cytoplasm and lower blood sugar by sending out glucose to the body. Our bodies usually only have fructose in the blood if we have an increase amount of glucose or high blood sugar ,this means we have elevated F1P levels and that is when glucokinase needs to be released .When F1P is low and our blood sugar is low and our blood glucose is low ,glucokinase will go into the nucleus.
When the liver senses hypoglycemia, it produces glucose to be sent to liver cells .Glycolysis reverses to gluconeogenesis to produce glucose to be released in the blood. With HFI,if there is an abundance of F1P because there is no Aldolase B,then our blood sugar is low and the liver will not be picking up the phosphate and it is not being used glycogen breakdown will be slowed down and not much glucose will get produced and glucose will not be getting released, that’s when you see symptoms of hypoglycemia .Also, symptoms of liver damage will result because there is no phosphate available for the ATP synthase ,because it is bound up ,the cells in the liver will die without the ATP production .If a person continues to ingest and not be able to metabolize the fructose a person can die .Symptoms of HFI are hypoglycemia,jaundic,nausea/vomiting, renal or liver damage or failure. .When bodies are overworked; our breathing will speed up as we try to get more oxygen delivered to our body cells. Most of our energy is made through aerobic methods; however, some situations need an accelerated more energy than our bodies can effectively make. That is when our bodies will cause muscles to generate energy through glycolysis. During glycolysis, glucose breaks down into pyruvate.
If our bodies have enough oxygen; pyruvate is goes into an aerobic pathway to be broken down and used for energy. When we don’t have enough oxygen, our body will temporarily change pyruvate into lactate and it will be sent through a cycle to change it to glucose. If there are high lactate levels in the muscle cells there will be a high level of acidity and other metabolites will be disrupted .The high lactate levels do prevent permanent muscle damage when muscles are exerted by slowing the primary systems needed for muscle contraction, but when the body rest, oxygen becomes available and the lactate changes back to pyruvate, allowing continued aerobic metabolism and energy for when a persons the body is recovering from an extreme physical exertion. In glycolysis, 2 ATP are produced to turn glucose into lactate, but in gluconeogenous, it takes 6 ATP to lactate back into glucose.
In our muscles glucose can combine with oxygen to generate energy. If there is not any oxygen, the anaerobic breakdown of glucose is achieved through glycolysis; however, ATP and Lactate are present through this process. In the normal presence of O2, glycolysis in muscle cells produces two units of ATP and two units of pyruvate. The two compounds provide the energy that enables a cell to perpetuate breathing through a series of chemical reactions called the Krebs cycle, also called the citric acid or tricarboxylic acid cycle. Oxidation pulls a carbon atom and 2 hydrogen atoms, water and carbon dioxide, out of the equation.
Higa, M. (2015) In the absence of oxygen, enzymes can break down the glucose carbohydrate by fermentation. Dehydrogenase enzyme in muscle cells converts it into lactate and the amino acid alanine. The liver filters the lactate out of blood to reverse engineer it to pyruvate and then into glucose. While two ATP molecules are produced by glycolysis in the muscles, it costs the liver six ATP molecules to feed the cycle by gluconeogenesis. If the Cori Cycle occurred in one cell, then glucose to lactate would make 2 ATP, but the lactate to glucose process would cost 6 ATP, this is a net loss of 4 ATP, if the cycle continued over and over then it would be a futile cycle.
If there is any defect with the enzymes in the citric acid cycle ,the cycle will not continue to function as it should, every step has a specific role and a lot of the time the enzymes and products relay on one to function properly for the next step to occur, an example would be :if citrate synthase did not occur or if there was a defect ,then Acetyl-CoA would not happen, nor would CoA,therefore ,the following steps in the CAC would not happen as they should and since it is a cycle, each part has to function properly. The biggest problem with a break in the CAC is that the ATP production is not possible because CAC products are sent to the Electron Transport Chain for Oxidative phosphorylation.
During the ETC ,products from Citric Acid Cycle are sent to the matrix of the mitochondria ,the workhouse of the eukaryotic cells ,and it is there ,that NADH and FADH2 are sent to a series of 4 complexes, first to complex 1 and then to complex 2 and then then both of them send their electrons to a co-enzyme ,named Q10, and then from there these products transfer to complex 3 and then to co-enzyme Cytochrome C and then complex 4 ,at this point these the electrons are given for oxygen to make water . This is called Aerobic Respirations.
Oxygen takes the electrons and makes water and then the hydrogen ions are pumped out across the intra membranes space. The complex I, III, and pushes these hydrogen ions out .The next complex are called ATP synthase. These hydrogen ions move through this complex and they have energy and they take ADP and phosphate and make it in ATP. Sanders, J. (2013) If any enzyme in the CAC stops working the amount of ATP is affected, example would be if citrate synthase is not working properly then citrate would not be made, also CoA nor would Acetyl- CoA, which is the molecule that enters the CAC.Subsequently the entire cycle is disrupted and then `the ETC will not have access to the products required for ATP production.
Sanders, J. (2013).Electron Transport Chain Retrieved from http://wgu.hosted.panopto.com/Panopto/Pages/Viewer/Default.aspx?id=9ec716ab-3610-47a4-bb37-41b4805935d6
Gilbert, S. (2014).Enzymes Retrieved from http://www.biologyreference.com/Dn-Ep/Enzymes.html
Sanders, J. (2013) Aldolase B and Hereditary Fructose Intolerance. Retrieved from http://wgu.hosted.panopto.com/Panopto/Pages/Viewer/Default.aspx?id=ce81226c-d293-4232-997e-fb2957530367
Higa, M. (2015) What is the Cori Cycle .Retrieved from http://www.wisegeek.com/what-is-the-cori-cycle.html
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