please help---What is the primary function of the TCA cycle in carbohydrate metabolism???  thank you!!!?
966445
The significance of the TCA cycle is that it takes the left-over carbon from glycolysis and breaks it down in such a way as to yield a large amount of useable energy.\n\nThe energy is first transferred to NAD+ through a highly charged hydrogen atom, and the result is shown as NADH + H+. This molecule carries the energy to the respiratory chain system, where three ATP molecules are energized from each one.
871738
A person would be fatigued because the mitochondria makes most of the energy from the metabolic pathway.  The long and complete answer is below.\n\nThe mitochondria is critical for the function of cellular metabolism.  The mitochondria has two membranes and inner membrane and an outer membrane.  The outer membrane is permeable to pretty much everything in the cell as it possesses large porous proteins, such as porin.\n\nThe inner mitochondrial membrane however is the membrane that separates the internal environment of the mitochondria from the environment present in the cell's cytoplasm.  The internal portion of the mitochondria is known as the matrix.  Inside the matrix the TCA cycle (Kreb's cycle) occurs and the proteins used for the electron transport chain is in the inner membrance of the mitochondria. \n\nAfter glycolysis (the breakdown of glucose or other sugars) the products are brought into the matrix.  Then the TCA cycle occurs in the matrix.  The main product of the TCA cycle is reducing power.  The reducing power of the TCA cycle is used in the electron transport chain.  The main effect of the electron transport chain is to pump protons out of the matrix to the cells cytoplasm.  This causes a lower proton concentration in the matrix.  Then the protons pumped out of the matrix move back into the matrix by passing through an ATPase pump.  The ATPase pump creates ATP (energy for the cell) for every four protons that move through the pump.  \n\nSo if the inner membrane of the mitochondria is made porous the protons pumped out of the matrix by the electron transport chain would just flow back into the matrix without going through the ATPase pump.  This would create an energy deficiency in the cell because much less ATP would be made.  Only three ATP would be made per glucose atom as opposed to about 34 that would be made using the ATPase pump.\n\nAdditionally a virus that makes the inner mitochondrial membrane porous will almost always kill the cell in humans.
337759
Kreb cycle and glycolysis - is what I initially answered\n\nHowever, if it is a standard test/textbook question the questioner is asking, then the answer is probably going to be 2 different mechanisms/pathways. It probably is going to be AEROBIC and ANAEROBIC metabolism.
564443
Carbohydrates are first.  Specifically, glucose.  \nFats are second.\nProteins are third.\nMinerals have no caloric value.\nVitamins CAN be metabolized for energy, but your body is probably having a lot of problems for that to happen.
985705
E is the answer.   i think its about 2 produced during glycolysis,  30 or 32 from TCA cycle and another 2 from going from glycolysis to TCA
846611
it`s very long. I`ll give u a simple explanation!\n\nfirst; glycolisis.\nthe suger is broken into 2 molecules of pyruvic acid\n\nsecond;\nthe pyruvic acid is changed into acethyl co-A\n\nthird; the krebs cycle\nthe acethyl co-A is reacted with oxaloacetate acids, and during the cycle CO2 is released, and those compound returned back in oxaloacetat acids\n\nfourth; electron chain systems
917473
It is the initial process of most carbohydrate catabolism, and it serves three principal functions:\nThe generation of high-energy molecules (ATP and NADH) as cellular energy sources as part of anaerobic respiration.\nProduction of pyruvate for the citric acid cycle as part of aerobic respiration.\nThe production of a variety of six- and three-carbon intermediate compounds, which may be removed at various steps in the process for other cellular purposes.\nAs the foundation of both aerobic and anaerobic respiration, glycolysis is one of the most universal metabolic processes known and occurs (with variations) in many types of cells in nearly all organisms. Glycolysis, through anaerobic respiration, is the main energy source in many prokaryotes, eukaryotic cells devoid of mitochondria (e.g. mature erythrocytes) and eukaryotic cells under low oxygen conditions (e.g. heavily exercising muscle or fermenting yeast).
953474
As you probably know, the breakdown of glucose is catalysed by a set of enzymes in a metabolic pathway; one that's very complex called glycolysis.\n\nIt would be unfeasable to have a unique metabolic pathway to breakdown every carbohydrate nutrient. Instead there's a collection of enzymes that convert these alternatives into a form that can be entered into the glycolytic pathway (the usual pathway). \n\nFor instance, the monosaccharide galactose is acted upon by the enzymes galactokinase and galactose 1-phosphate uridyl transferase. After these 2 metabolic steps, galactose is converted into glucose-1-phosphate; this then enters glycolysis.
867325
I guess that your teacher would like to know if you are familiar with the two metabolic activities of photosynthesis: the "light" and "dark" reactions. \n\n"Light dependent reactions" means the system for electron transport to load ATP, and "light independent reactions" ("dark reactions") contains the enzymatic system to build up glucose from CO2, which was the specified feature of photosynthesis your teacher was asking for.
806722
OK. watch this.\nThe FADH and NADH from the Krebs cycle enters the electron transport chain. This is on the cristae on the mitochondria (those Lil protrusions). there, the NADH and FADH separate in to the Hydrogen and electons. The electrons are passed from electron acceptor to electron acceptor. The energy level of each electron acceptor is lower than that of the previous, so the elctrons are losing energy. This energy is used to drive hydrogen ions into the spaces between the mitochondrial membrane. By the process of chemiosmosis, the Hydrogen then passes through a special protein (ATP Synthase) in the membrane back into the cristae. When Hydrogen passes through this protein it stimulates the production of ATP. Simply, the protein which catalyse ATP production is an enzyme, activated by the passage of Hydrogen through it. Get it? [Cambrigde A'Level Whooohoo!lol] \n\nWell it is more than three NADH. The cycle goes around twice per glucose molecule so it is 6 NADH (3 each time), and 2 FADH (1 each time) plus the 4 NADH from the stages before the Krebs cycle. All of these enter the electron transport chain. That is the purpose of the NAD and FAD, to take hydrogen and electrons from the Krebs cycle etc. to the next stage (oxidative phosphorylation). That is partially right. The NADH itself does not enter the membrane. It stays on the surface. It is The HYDROGEN that passes into the membrane.
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I think (only think) it's because pyruvate (a product of glycolysis) is able to cross the internal membrane thus allowing ATP production with carbon dioxide as a by-product, whilst glucose is unable to do so.\nI would read my two references to check.\nGood luck.
64087
This is a very involved question you have asked if I answer it at an advanced level.  \nYou don抰 say what school you are in or what your present grade level is,\nso I will assume you are fairly young.\nThe first thing that happens to the food that we eat is that the digestive system \nphysically and chemically breaks it down into smaller and smaller particles until it \ncan be absorbed through the intestinal walls as individual molecules.  These molecules\n then enter the blood capillaries and are distributed throughout the body to be taken\nup by cells that need the \n(1) carbohydrate molecules for the energy , \n(2) amino acid molecules for building proteins, or \n(3) lipid molecules (fat) for building membranes, certain of the hormones, \nand other things, or just to store this concentrated form of potential energy \n(the fat molecules) for a rainy day.\nThose cells that start using the carbohydrate molecules for energy is where the bulk of \nthe heat is produced.  What happens first is that the carbohydrate has to be absorbed \nas glucose or another closely related monosaccharide molecule that the cell can change \nto glucose.  The glucose is then metabolized (broken down) to carbon dioxide and water \nthrough a large number of chemical steps that builds ATP molecules (the energy storage \n揷ellular bullets? that can be use for almost all the cell抯 needs for reactions that require\nenergy in an easily usable from.  Building the ATP and using the ATP is like you burning a \ntwig out in the yard (in a safe place, of course) to heat a small cup of soup.  The wood, \nas it burns, combines with oxygen and is changed into carbon dioxide and water, plus a \nlittle smoke which is a leftover product of incomplete burning of the wood.  Now the body \nis much more efficient than this and doesn抰 leave any smoke as it consumes the glucose \nand produces the ATP molecules.  Cells do produce heat while 揵urning?the glucose and \nwhile using the ATP just like the fire heating the soup.\nFor a more detailed description of these biochemical events you can go to any good \nbiochemistry textbook and it will give you the actual molecular reactions.  I have one such \nbook 揃iochemistry?3rd edition, by Lubert Stryer, published by W. H. Freeman and Company, \nNew York.  There are two reference in this book on heat production; page 421 at the bottom, \nand page 443-4.  The last section gives a fascinating description of how molecular 揵urning?\nproduces enough heat in the bumblebee抯 thorax to allow him to fly even when it is cold outside.\n\nNow I haven抰 even talked about the control of heat production, but the cells can burn \noxygen with glucose to produce the ATP and heat in some of their reactions or sometimes \nthe cells do not use oxygen while 揵urning?a different molecule to produce the heat.  \nBut whatever the metabolic pathways involved in producing heat, this activity is controlled \nby a hormone from the thyroid gland.  The term basal metabolic rate (BMR) is used to talk \nabout this level of activity and thyroxin, or really triiodothyronine, another thyroid hormone, \nis responsible for maintaining the appropriate level of metabolism that will keep your \ntemperature at approximately 37 degrees centigrade throughout your life when you are healthy.  \nYou can find a very good detailed explanation of this system in any endocrinology textbook.  \nI happen to like 揃asic and Clinical Endocrinology?5th edition, by Francis Greenspan and Gordon  \nStrewler, published by Appleton & Lange, Stamford, Connecticut.  Pages 214-215 deal with this \ntopic in their book.\nGo to your local library and take a look around for these types of books and you will have many \nhours of enjoyable reading.
215597
Hmm, you're right, the methods section of that paper is not very clear.  Anyway, check out the ref below.  Look midway through the 4th paragraph under Results, titled "Effect of recombinant Acrp30 infusion on hepatic glucose fluxes."  There could be other methods, but this is what I found.  Good luck.
576212
Many, many functions:\n\nThe liver produces and excretes bile required for food digestion. \n\nThe liver performs several roles in carbohydrate metabolism: \nGluconeogenesis (the formation of glucose from certain amino acids, lactate or glycerol) \nGlycogenolysis (the formation of glucose from glycogen) \nGlycogenesis (the formation of glycogen from glucose) \nThe breakdown of insulin and other hormones \n\nThe liver is responsible for the mainstay of protein metabolism. \n\nThe liver also performs several roles in lipid metabolism: \nCholesterol synthesis \nThe production of triglycerides (fats). \nThe liver produces coagulation factors I (fibrinogen), II (prothrombin), V, VII, IX, and XI, as well as protein C, protein S and antithrombin. \n\nThe liver breaks down hemoglobin, creating metabolites that are added to bile as pigment. \n\nThe liver breaks down toxic substances and most medicinal products in a process called drug metabolism. This sometimes results in toxication, when the metabolite is more toxic than its precursor. \n\nThe liver converts ammonia to urea. \n\nThe liver stores a multitude of substances, including glucose in the form of glycogen, vitamin B12, iron, and copper.
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* The process begins with the oxidation of pyruvate, producing one CO2, and one acetyl-CoA.\n    * Acetyl-CoA reacts with the four carbon carboxylic acid, oxaloacetate--to form the six carbon carboxylic acid, citrate.\n    * Through a series of reactions citrate is converted back to oxaloacetate. This cycle produces 2 CO2 and consumes 3 NAD+, producing 3NADH and 3H+.\n    * It consumes 3 H2O and consumes one FAD, producing one FADH+.\n    * 1st turn end= 1 ATP, 3 NADH, 1 FADH2\n    * Since there are two molecules of Pyruvic acid to deal with, the cycle turns once more.\n    * The complete end result= 2 ATP, 6 NADH, 2 FADH2
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There are four important mammalian hexokinase isozymes that vary somewhat in their locations, kinetic characteristics with respect to different substrates and operating conditions, and physiological functions. They are designated hexokinases I, II, III, and IV or hexokinases A, B, C, and D.\n\nHexokinases I, II, and III are referred to as "low-Km" isozymes because of a high affinity for glucose even at low concentrations (below 1 mM). All three are strongly inhibited by their product, glucose-6-phosphate. Molecular weights are around 100 kD. Each consists of two similar 50kD halves, but only in hexokinase II do both halves have functional active sites.\n\nHexokinase I (hexokinase A) is found in all mammalian tissues, and is considered a "housekeeping enzyme," unaffected by most physiological, hormonal, and metabolic changes.\n\nHexokinase III (or C) is inhibited by excessive glucose (substrate inhibition).\n\nMammalian hexokinase IV, also referred to as glucokinase, has unique characteristics and functions compared to other hexokinases. The location of the phosphorylation on a subcellular level occurs when glucokinase translocates between the cytoplasm and nucleus of liver cells. Glucokinase can only phosphorylate glucose if the concentration of this substrate is high enough; its Km for glucose is 100 times higher than that of hexokinases I, II, and III. It is monomeric, about 50kD, displays positive cooperativity with glucose, and is not allosterically inhibited by its product, glucose-6-phosphate. It is present in the liver, pancreas, hypothalamus, small intestine, and perhaps certain other neuroendocrine cells, and plays an important regulatory role in carbohydrate metabolism. In the beta cells of the pancreatic islets, it serves as a glucose sensor to control insulin release, and similarly controls glucagon release in the alpha cells. In hepatocytes of the liver, glucokinase responds to changes of ambient glucose levels by increasing or reducing glycogen synthesis.
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well,the main metabolic function of liver are:\n1.produces and excretes bile.\n2.performs several roles in carbohydrate metabolism like Gluconeogenesis,Glycogenolysis &Glycogenesis.\n3. breakdown of insulin and other hormones. \n4.Cholesterol synthesis.\n5. production of triglycerides (fats). \n6.liver produces coagulation factors which are I (fibrinogen),II (prothrombin),V,VII,IX,and XI as well as protein C, protein S and antithrombin.\n7.converts ammonia to urea.\n8.stores a multitude of substances like glycogen,vitamin B12,iron,and copper.\n9.the main site of red blood cell production in the first trimester fetus.