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Can Triglycerides Be Converted To Glucose?

Chapter Summary

Chapter Summary

Metabolism is the sum of all the chemical and physical processes by which the body breaks down and builds up molecules. All forms of life maintain a balance between anabolic and catabolic reactions, which determines if the body achieves growth and repair or if it persists in a state of loss. Metabolic pathways are clusters of chemical reactions that occur sequentially and achieve a particular goal, such as the breakdown of glucose for energy. These pathways are carefully controlled, either turned on or off, by hormones released within the body. Condensation and hydrolysis are chemical reactions involving water, whereas phosphorylation is a chemical reaction in which phosphate is transferred. In oxidation-reduction reactions, the molecules involved exchange electrons. Enzymes, coenzymes, and cofactors increase the efficiency of metabolism. Glucose oxidation occurs in three well-defined stages: glycolysis, the TCA cycle, and oxidative phosphorylation via the electron transport chain. The end products of glucose oxidation are carbon dioxide, water, and ATP. During glycolysis, six-carbon glucose is converted into two molecules of three-carbon pyruvate. If glycolysis is anaerobic, this pyruvate is converted to lactic acid. If glycolysis is aerobic, this pyruvate is converted to acetyl CoA and enters the TCA cycle. During the TCA cycle, acetyl CoA coming from either carbohydrate,fat, or protein metabolism results in the production of GTP or ATP, NADH, and FADH2. These two final compounds go through oxidative phosphorylation (as part of the electron transport chain) to produce energy. During oxidative phosphorylation, the NADH and the FADH2 enter the electron transport chain where, through a series of reactions, ATP is produced. Triglycerides are broken down into glycerol and Continue reading >>

Metabolism: Transformations And Interactions

Metabolism: Transformations And Interactions

What are energy-yielding nutrients broken down into? Monosaccharides, fatty acids, glycerol, and amino acids. What are the broken down nutrients of energy-yielding nutrients further broken into? Has a role in digestions, processes toxins like alcohol, drugs, and poisons. Break down body compounds, release energy. High energy compound. Adenosine Triphosphate. High energy bond. Protein catalysts that cause chemical reactions. Organic molecules that function as enzyme helpers. Organic or inorganic substances that facillitate enzyme action. What do all energy-yielding nutrients enter? TCA cycle (tricarboxylic acid), and Electron Transport Chain. Anaerobically - Lactic Acid. Aerobically - Acetyl CoA. Synthesize fats when the body has enough ATP. Generate ATP when cell is low on energy. What can not be used to synthesize glucose? Red blood cells, brain, and nervous system. What is a fairly good source of glucose when CHO not available? What are the two possible products of Deamination? Transfer of amino groups from AA to Keto acid. - Ammonia converted to urea in liver thats excreted via kidneys. 4 Carbon compound, required in firs step, synthesized in last. Deficit slows cycle. Made primarily from pyruvate and some AA. Cannot be made from fat. What is the Electron Transport Chains purpose? Consumes 02, produces C02 and H20, produces energy as ATP. What provides more energy per gram than CHO and PRO? Fat. - Easily oxidized results in more ATP. Fill liver and muscle glycogen stores, excess converted too body fat. What happens in feasting with Fatty Acids? Deamination - nitrogen excreted as urea. Carbon skeleton is converted to body fat. Once glycogen stores are used up, amino acids are initally converted to glucose at rapid rate. Glycerol supplies a small amount of glucose. Fa Continue reading >>

The Conversion Of Carbohydrates To Triglycerides

The Conversion Of Carbohydrates To Triglycerides

Eating a diet high in simple carbohydrates can raise your level of triglycerides—fats carried in the blood and stored in fat cells. The body turns carbohydrates into glucose to use for fuel, but will store excess glucose as fat. High levels of triglycerides can increase your risk for heart disease. Triglycerides are fats. You eat triglycerides in the form of foods such as butters and oil, but your body also makes triglycerides from excess calories, especially from alcohol or from the simple carbohydrates found in sugar-rich foods. Triglycerides help transport cholesterol, which is essential for brain and nerve function, to your cells. Trigylcerides also carry glucose, or blood sugar, to your fat cells. Carbohydrates in the Diet Dietary carbohydrates fall into two categories: simple carbohydrates, or sugars, and complex carbohydrates, or starch and fiber. Most of the simple carbohydrates in the American diet come from sugar, or sucrose, and high-fructose corn syrup, used to sweeten a wide variety of foods. Fruit juices also contribute simple sugars. Whole fruit contains simple sugars, but also contains fiber, which helps slow down the digestion of glucose. All carbohydrates supply the body with glucose, which is used for immediate energy needs and stored as glycogen in the liver and muscle cells. Eating too many simple carbohydrates is harmful, according to the Cleveland Clinic. How Carbs Turn into Fat Your body digests simple sugars and refined carbohydrates such as white rice and white flour rapidly, causing a spike in blood glucose. This causes the pancreas to release more insulin. When your body has more glucose than it needs for energy and has reached its storage capacity for glycogen, the increased insulin prompts the liver to convert glucose into triglycerides, Continue reading >>

The Catabolism Of Fats And Proteins For Energy

The Catabolism Of Fats And Proteins For Energy

Before we get into anything, what does the word catabolism mean? When we went over catabolic and anabolic reactions, we said that catabolic reactions are the ones that break apart molecules. To remember what catabolic means, think of a CATastrophe where things are falling apart and breaking apart. You could also remember cats that tear apart your furniture. In order to make ATP for energy, the body breaks down mostly carbs, some fats and very small amounts of protein. Carbs are the go-to food, the favorite food that cells use to make ATP but now we’re going to see how our cells use fats and proteins for energy. What we’re going to find is that they are ALL going to be turned into sugars (acetyl) as this picture below shows. First let’s do a quick review of things you already know because it is assumed you learned cell respiration already and how glucose levels are regulated in your blood! Glucose can be stored as glycogen through a process known as glycogenesis. The hormone that promotes this process is insulin. Then when glycogen needs to be broken down, the hormone glucagon, promotes glycogenolysis (Glycogen-o-lysis) to break apart the glycogen and increase the blood sugar level. Glucose breaks down to form phosphoglycerate (PGAL) and then pyruvic acid. What do we call this process of splitting glucose into two pyruvic sugars? That’s glycolysis (glyco=glucose, and -lysis is to break down). When there’s not enough oxygen, pyruvic acid is converted into lactic acid. When oxygen becomes available, lactic acid is converted back to pyruvic acid. Remember that this all occurs in the cytoplasm. The pyruvates are then, aerobically, broken apart in the mitochondria into Acetyl-CoA. The acetyl sugars are put into the Krebs citric acid cycle and they are totally broken Continue reading >>

Glycogen And Triglycerides - Lecture 5

Glycogen And Triglycerides - Lecture 5

glucose concentration will fall during the ____ state ____ plays a crucial role in regulating blood glucose during the postabsoptive / fasting state liver can ________ G6P in cells and the ____ can pump glucose back into the bloodstream which hormone helps break down glycogen and triglycerides glucagon is produced by the ___ cells in the pancreas alpha islet cells in the pancreas detect _____ glucagon interacts with cells in the liver so that they release glucose into the bloodstream by when blood glucose levels ___, we inhibit the secretion of glucagon when blood glucose levels rise we _____ secretion of glucagon glucagon is secreted when you are fasting in order to gluconeogenesis is the formation of glucose from what is the formation of glucose from non glucose sources called an example of gluconeogenesis is the ____ cycle in muscle cell, ___ can be converted to ____ what is secreted by the muscle and enters the liver in the glucose alanine cycle alanine is secreted by ____ and enters the ____ in the glucose alanine cycle in the liver, alanine is converted back to _____ to create ____ when does the glucose alanine cycle happen? we breakdown _____ for energy as a substrate when you are starving, the body will break down _____ in skeletal muscle what is transamination stage of amino acid breakdown during transamination, ____ in the liver interacts with an amino acid during transamination of the breakdown of amino acids, amine group is converted from _____ to a ______ after transamination of the breakdown of amino acids, the result is the production of a new _____ and a new _____ (also known as ______) what is the stage called in amino acid breakdown when the amine group is detached from glutamic acid to produce ammonia what is oxidative deamination stage in amino acid Continue reading >>

We Really Can Make Glucose From Fatty Acids After All! O Textbook, How Thy Biochemistry Hast Deceived Me!

We Really Can Make Glucose From Fatty Acids After All! O Textbook, How Thy Biochemistry Hast Deceived Me!

Biochemistry textbooks generally tell us that we can’t turn fatty acids into glucose. For example, on page 634 of the 2006 and 2008 editions of Biochemistry by Berg, Tymoczko, and Stryer, we find the following: Animals Cannot Convert Fatty Acids to Glucose It is important to note that animals are unable to effect the net synthesis of glucose from fatty acids. Specficially, acetyl CoA cannot be converted into pyruvate or oxaloacetate in animals. In fact this is so important that it should be written in italics and have its own bold heading! But it’s not quite right. Making glucose from fatty acids is low-paying work. It’s not the type of alchemy that would allow us to build imperial palaces out of sugar cubes or offer hourly sweet sacrifices upon the altar of the glorious god of glucose (God forbid!). But it can be done, and it’ll help pay the bills when times are tight. All Aboard the Acetyl CoA! When we’re running primarily on fatty acids, our livers break the bulk of these fatty acids down into two-carbon units called acetate. When acetate hangs out all by its lonesome like it does in a bottle of vinegar, it’s called acetic acid and it gives vinegar its characteristic smell. Our livers aren’t bottles of vinegar, however, and they do things a bit differently. They have a little shuttle called coenzyme A, or “CoA” for short, that carries acetate wherever it needs to go. When the acetate passenger is loaded onto the CoA shuttle, we refer to the whole shebang as acetyl CoA. As acetyl CoA moves its caboose along the biochemical railway, it eventually reaches a crossroads where it has to decide whether to enter the Land of Ketogenesis or traverse the TCA cycle. The Land of Ketogenesis is a quite magical place to which we’ll return in a few moments, but n Continue reading >>

Jbc : Journal Of Biological Chemistry

Jbc : Journal Of Biological Chemistry

During fasting in all mammals, triglyceride stored in adipose tissue is hydrolyzed by a hormone-sensitive lipase to produce free fatty acids (FFA) 1 and glycerol. Detailed studies of the balance of glycerol and FFA released from white adipose tissue (WAT) during starvation have noted considerable re-esterification of the FFA in adipose tissue during periods of active lipolysis. For example, in rats fasted for 24 h, about 30% of the FFA is recycled back to triglyceride in WAT ( 1 ). In humans, the recycling in this tissue has been estimated to be as high as 40% ( 2 ). The recycling of FFA also occurs in the liver as part of a triglyceride/fatty acid cycle that accounts for a considerable quantity of fatty acid recycling. Thus the triglyceride/fatty acid cycle includes local intracellular cycling within the adipose tissue and extracellular or systemic recycling, i.e. the formation of triglycerides in the liver and possibly skeletal muscle ( Fig. 1 ). Almost 30 years ago, Newsholme and Crabtree ( 3 ) discussed the importance of this cycle in metabolic regulation and heat production. Quantitative estimates of the triglyceride/fatty acid cycle in human adults and newborn infants and studies in animals show that only a small fraction of the FFA released as a result of lipolysis in the WAT are oxidized, and the majority are re-esterified to triglycerides in various tissues ( 2 9 ). The quantitative estimates of triglyceride/fatty acid cycling vary in different studies in humans, depending upon the methodology employed. Intracellular recycling (primarily fatty acid re-esterification in WAT) appears to represent 2030% of the total, whereas non-adipose tissue recycling (primarily hepatic) accounts for 50% of re-esterification of fatty acids in healthy adults after an overnight f Continue reading >>

24.3 Lipid Metabolism

24.3 Lipid Metabolism

By the end of this section, you will be able to: Describe how, when, and why the body metabolizes lipids Explain how energy can be derived from fat Explain the purpose and process of ketogenesis Describe the process of ketone body oxidation Explain the purpose and the process of lipogenesis Fats (or triglycerides) within the body are ingested as food or synthesized by adipocytes or hepatocytes from carbohydrate precursors ( Figure 1 ). Lipid metabolism entails the oxidation of fatty acids to either generate energy or synthesize new lipids from smaller constituent molecules. Lipid metabolism is associated with carbohydrate metabolism, as products of glucose (such as acetyl CoA) can be converted into lipids. Figure 1. Triglyceride Broken Down into a Monoglyceride A triglyceride molecule (a) breaks down into a monoglyceride and two free fatty acids (b). Lipid metabolism begins in the intestine where ingested triglycerides are broken down into free fatty acids and a monoglyceride molecule (see Figure 1 b) by pancreatic lipases, enzymes that break down fats after they are emulsified by bile salts. When food reaches the small intestine in the form of chyme, a digestive hormone called cholecystokinin (CCK) is released by intestinal cells in the intestinal mucosa. CCK stimulates the release of pancreatic lipase from the pancreas and stimulates the contraction of the gallbladder to release stored bile salts into the intestine. CCK also travels to the brain, where it can act as a hunger suppressant. Once the bile salts have emulsified the triglycerides, the pancreatic lipases down triglycerides into free fatty acids. These fatty acids can be transported across the intestinal membrane. However, once they cross the membrane, they are recombined to again form triglyceride molecules Continue reading >>

How Sugar, Not Fat, Raises Your Cholesterol

How Sugar, Not Fat, Raises Your Cholesterol

Excess carbohydrates and sugar lead to cholesterol and weight gain, explains Dr. Doni Wilson, which is why balancing blood sugar levels every day is so important. When you go to the doctor and get a cholesterol reading, you may be cautioned against eating high-fat foods. But very little fat from foods becomes cholesterol in your blood. What produces cholesterol is rather the excessive consumption of carbs at any one time. The cholesterol and triglycerides in your bloodstream come not from consuming excess fat, but rather, from consuming excess glucose. I’m not just talking about excess glucose over the course of a week or even a day. I’m talking about what happens when you consume excess glucose in one sitting. Let’s take a closer look at exactly happens when your body gets too many carbs at one particular meal. First, you digest the carb-containing food, breaking it down into the individual glucose molecules that are small enough to cross the cells of your intestinal walls and enter your bloodstream. Because you have eaten too many carbs, you have far too much glucose stuck in your blood. You don’t have enough insulin to move all that glucose into your cells. So what happens to that excess glucose? Some of it is stored in your liver as a substance known as glycogen, to be released when you don’t eat. Harking back to our hunter-gatherer days, our bodies created a backup system to ensure that even if we can’t get any food for a couple of days, we won’t starve to death. The liver can only hold so much glycogen, however. So what about the glucose that doesn’t fit? Your body has three choices: convert the glucose into body fat, which translates into weight gain, most likely around your middle; convert the glucose into lipids (fats), which remain in your bloo Continue reading >>

Glycogen & Triglycerides

Glycogen & Triglycerides

Eating more carbs can help increase glycogen storage.Photo Credit: EvgeniaSh/iStock/Getty Images When you eat more calories than you need, your body has two ways to store this extra energy -- glycogen and triglycerides, or fat. When your body needs extra energy, it pulls it from these two sources, and what kind of exercise you do, how intensely and for how long affects where the energy to fuel it comes from. When you eat carbohydrates, they are turned into glucose during digestion. The increase in glucose in your blood leads to the release of insulin, which in turn triggers the storage of glycogen in your muscle and liver cells. This glycogen gives your body an easily accessible source of energy for the future for your brain, nervous system and muscles during high-intensity exercise. Your body only stores about 1,200 to 1,600 calories worth of energy in the form of glycogen. Diets that contain a lot of carbohydrates are best for increasing glycogen stores. If conditions aren't right for forming glycogen, you'll form intramuscular fatty acids. These are a type of triglyceride that your muscles can access relatively quickly and use during long periods of moderate exercise when there isn't enough glycogen. Between 2,000 and 3,000 calories worth of energy can be stored as intramuscular triglyceride. Once glycogen stores are full, your liver cells send any extra glucose to be turned into triglycerides and stored in your fat cells. Anywhere from 50,000 to 60,000 calories of energy are typically stored as triglycerides in fatty tissue. When your body needs energy for exercise, it comes from three sources -- glucose in your blood, glycogen in your muscles and liver, and triglycerides in your fat cells and in the form of free fatty acids. Blood sugar is the easiest for your bod Continue reading >>

Conversion Of Carbohydrate To Fat In Adipose Tissue: An Energy-yielding And,therefore, Self-limiting Process.

Conversion Of Carbohydrate To Fat In Adipose Tissue: An Energy-yielding And,therefore, Self-limiting Process.

Conversion of carbohydrate to fat in adipose tissue: an energy-yielding and,therefore, self-limiting process. A theoretical analysis of the energy metabolism associated with the conversion ofglucose to fat is presented. In tissues where the pentose cycle furnishes some ofthe NADPH required for fatty acid synthesis, this conversion is an ATP-yieldingprocess. In rat adipose tissue the maximal rate of glucose conversion to fat can be quantatively predicted on the basis of the tissue's ability to use the ATPwhich is generated in excess during this conversion. The energy-generating natureof this process provides the means for a type of regulation which depends onmetabolic state and which, during fasting, contributes to the sparing ofcarbohydrate. Impairment of lipogenesis in the fasting state is attributed to adecrease in the activity of the malate cycle and to the presence of free fattyacids. However, rather than by inhibiting specific enzymes, it is by virtue oftheir quality as substrates for energy production that free fatty acids and theirCoA derivatives appear to inhibit de novo lipogenesis. The regulatory phenomenadiscussed here may explain the failure of the attempts made to identify therate-limiting step for de novo lipogenesis in adipose tissue. Continue reading >>

Converting Carbohydrates To Triglycerides

Converting Carbohydrates To Triglycerides

Consumers are inundated with diet solutions on a daily basis. High protein, low fat, non-impact carbohydrates, and other marketing “adjectives” are abundant within food manufacturing advertising. Of all the food descriptors, the most common ones individuals look for are “fat free” or “low fat”. Food and snack companies have found the low fat food market to be financially lucrative. The tie between fat intake, weight gain, and health risks has been well documented. The dietary guidelines suggest to keep fat intake to no more than 30% of the total diet and to consume foods low in saturated and trans fatty acids. But, this does not mean that we can consume as much fat free food as we want: “Fat free does not mean calorie free.” In many cases the foods that are low in fat have a large amount of carbohydrates. Carbohydrate intake, like any nutrient, can lead to adverse affects when over consumed. Carbohydrates are a necessary macronutrient, vital for maintenance of the nervous system and energy for physical activity. However, if consumed in amounts greater than 55% to 65% of total caloric intake as recommended by the American Heart Association can cause an increase in health risks. According to the World Health Organization the Upper Limit for carbohydrates for average people is 60% of the total dietary intake. Carbohydrates are formed in plants where carbons are bonded with oxygen and hydrogen to form chains of varying complexity. The complexity of the chains ultimately determines the carbohydrate classification and how they will digest and be absorbed in the body. Mono-and disaccharides are classified as simple carbohydrates, whereas polysaccharides (starch and fiber) are classified as complex. All carbohydrates are broken down into monosaccharides before b Continue reading >>

Lipid Metabolism

Lipid Metabolism

on on Fats (or triglycerides) within the body are ingested as food or synthesized by adipocytes or hepatocytes from carbohydrate precursors ([link]). Lipid metabolism entails the oxidation of fatty acids to either generate energy or synthesize new lipids from smaller constituent molecules. Lipid metabolism is associated with carbohydrate metabolism, as products of glucose (such as acetyl CoA) can be converted into lipids. Lipid metabolism begins in the intestine where ingested triglycerides are broken down into smaller chain fatty acids and subsequently into monoglyceride molecules (see [link]b) by pancreatic lipases, enzymes that break down fats after they are emulsified by bile salts. When food reaches the small intestine in the form of chyme, a digestive hormone called cholecystokinin (CCK) is released by intestinal cells in the intestinal mucosa. CCK stimulates the release of pancreatic lipase from the pancreas and stimulates the contraction of the gallbladder to release stored bile salts into the intestine. CCK also travels to the brain, where it can act as a hunger suppressant. Together, the pancreatic lipases and bile salts break down triglycerides into free fatty acids. These fatty acids can be transported across the intestinal membrane. However, once they cross the membrane, they are recombined to again form triglyceride molecules. Within the intestinal cells, these triglycerides are packaged along with cholesterol molecules in phospholipid vesicles called chylomicrons ([link]). The chylomicrons enable fats and cholesterol to move within the aqueous environment of your lymphatic and circulatory systems. Chylomicrons leave the enterocytes by exocytosis and enter the lymphatic system via lacteals in the villi of the intestine. From the lymphatic system, the chylo Continue reading >>

Triglycerides - What Do They Do?

Triglycerides - What Do They Do?

Triglycerides are a type of fat that plays a major role as an energy source when they are metabolized in the human body. They are very rich in energy, containing double the energy of either carbohydrates or proteins that can also be used to supply energy to the body. As a normal component of the vascular system, triglycerides are continually in circulation ready to be metabolized to provide a source of energy. When present in excess, triglycerides can be stored in fatty deposits, which may lead to obesity and related health conditions if it extends over time. Triglyceride Metabolism The chemical structure of triglycerides is composed of a glycerol molecule that is bound to three fatty acid chains. These three fatty acids can vary on each triglyceride to create many different types of triglycerides. Through a process known as lipolysis, triglycerides are broken down to release the fatty acids from the monoacylglycerol in the intestine, simultaneously secreting lipases and bile. The triglycerides can then be reconstructed in the enterocytes to incorporate cholesterol and proteins to form chylomicrons. Chylomicrons then move into the lymph system and the vascular system to be transported around the body as an energy supply. It is the glycerol component of the triglyceride that is the most useful to the body in providing a source of energy, as it is easily converted into glucose, which can be used to supply the brain with energy. The fatty acids can also provide energy, but must be converted to a ketone chemical structure in order to be utilized. Triglycerides as a complete molecule cannot be absorbed into the cells of the body from the bloodstream and must be broken down into its separate components in order to be utilized. Triglyceride Storage When there is an excess of t Continue reading >>

Triglyceride

Triglyceride

Example of an unsaturated fat triglyceride (C55H98O6). Left part: glycerol; right part, from top to bottom: palmitic acid, oleic acid, alpha-linolenic acid. A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from tri- and glyceride).[1] Triglycerides are the main constituents of body fat in humans and other animals, as well as vegetable fat.[2] They are also present in the blood to enable the bidirectional transference of adipose fat and blood glucose from the liver, and are a major component of human skin oils.[3] There are many different types of triglyceride, with the main division between saturated and unsaturated types. Saturated fats are "saturated" with hydrogen — all available places where hydrogen atoms could be bonded to carbon atoms are occupied. These have a higher melting point and are more likely to be solid at room temperature. Unsaturated fats have double bonds between some of the carbon atoms, reducing the number of places where hydrogen atoms can bond to carbon atoms. These have a lower melting point and are more likely to be liquid at room temperature. Chemical structure[edit] Triglycerides are chemically tri esters of fatty acids and glycerol. Triglycerides are formed by combining glycerol with three fatty acid molecules. Alcohols have a hydroxyl (HO–) group. Organic acids have a carboxyl (–COOH) group. Alcohols and organic acids join to form esters. The glycerol molecule has three hydroxyl (HO–) groups. Each fatty acid has a carboxyl group (–COOH). In triglycerides, the hydroxyl groups of the glycerol join the carboxyl groups of the fatty acid to form ester bonds: HOCH2CH(OH)CH2OH + RCO2H + R′CO2H + R″CO2H → RCO2CH2CH(O2CR′)CH2CO2R″ + 3H2O The three fatty acids Continue reading >>

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