Macronutrients
Overview Carbohydrates, fats and proteins are macronutrients. We require them in relatively large amounts for normal function and good health. These are also energy-yielding nutrients, meaning these nutrients provide calories. On This Page: What are Carbohydrates? Carbohydrates Understanding Carbohydrates Every few years, carbohydrates are vilified as public enemy number one and are accused of being the root of obesity, diabetes, heart disease and more. Carb-bashers shun yogurt and fruit and fill up on bun-less cheeseburgers. Instead of beans, they eat bacon. They dine on the tops of pizza and toss the crusts into the trash. They so vehemently avoid carbs and spout off a list of their evils that they may have you fearing your food. Rest assured, you can and should eat carbohydrates. In fact, much of the world relies on carbohydrates as their major source of energy. Rice, for instance, is a staple in Southeast Asia. The carbohydrate-rich potato was so important to the people of Ireland that when the blight devastated the potato crop in the mid 1800s, much of the population was wiped out. What are Carbohydrates? The basic structure of carbohydrates is a sugar molecule, and they are classified by how many sugar molecules they contain. Simple carbohydrates, usually referred to as sugars, are naturally present in fruit, milk and other unprocessed foods. Plant carbohydrates can be refined into table sugar and syrups, which are then added to foods such as sodas, desserts, sweetened yogurts and more. Simple carbohydrates may be single sugar molecules called monosaccharides or two monosaccharides joined together called disaccharides. Glucose, a monosaccharide, is the most abundant sugar molecule and is the preferred energy source for the brain. It is a part of all disaccharides Continue reading >>
Muscle Physiology - Metabolism Of Fatty Acids
Fat molecules consist of three fatty acid chains connected by a glycerol backbone. Fatty acids are basically long chains of carbon and hydrogen and are the major source of energy during normal activities. Fatty acids are broken down by progressively cleaving two carbon bits and converting these to acetyl coenzyme A. The acetyl CoA is the oxidized by the same citric acid cycle involved in the metabolism of glucose. For every two carbons in a fatty acid, oxidation yields 5 ATP s generating the acetyl CoA and 12 more ATP s oxidizing the coenzyme. This makes fat a terrific molecule in which to store energy, as the body well knows (much to our dismay). The only biological drawback to this, and other, forms of oxidative metabolism is its dependence on oxygen. Thus, if energy is required more rapidly than oxygen can be delivered, muscles switch to the less efficient anaerobic pathways. Interestingly, this implies that an anaerobic workout will not "burn" any fat, but will preferentially deplete the body of glucose. Of course, your body can't survive very long on just anaerobic metabolism...it just can't generate enough energy. Last Updated: Friday, 13-Jan-2006 15:56:16 PST For questions or comments regarding this site, please e-mail the webmaster . Copyright 2000, University of California Regents. All rights reserved. Continue reading >>
How Does The Body Adapt To Starvation?
- [Instructor] In this video, I want to explore the question of how does our body adapt to periods of prolonged starvation. So in order to answer this question, I actually think it's helpful to remind ourselves first of a golden rule of homeostasis inside of our body. So in order to survive, remember that our body must be able to maintain proper blood glucose levels. I'm gonna go ahead and write we must be able to maintain glucose levels in our blood, and this is important even in periods of prolonged starvation, because it turns out that we need to maintain glucose levels above a certain concentration in order to survive, even if that concentration is lower than normal. And this of course brings up the question, well, how does our body maintain blood glucose levels? So let's go ahead and answer this question by starting off small. Let's say we have a mini case of starvation, let's say three or four hours after a meal. Your blood glucose levels begin to drop, and so what does your body do to resolve that? Well, at this point, it has a quick and easy solution. It turns to its glycogen stores in the liver. Remember that our body stores up these strings of glucose inside of our body so that we can easily pump it back into the blood when we're not eating. But unfortunately humans only have enough glycogen stores to last us about a day, so after a day of starvation, our body's pretty much reliant exclusively on the metabolic pathways involved in gluconeogenesis, which if you remember is the pathway by which we produce new or neo glucose. And we produce this glucose from non-carbohydrate precursor molecules. So let's think about what else we have in our body. Remember that our other two major storage fuels are fats, and we usually think about fatty acids containing most of th Continue reading >>
Does Fat Convert To Glucose In The Body?
Your body is an amazing machine that is able to extract energy from just about anything you eat. While glucose is your body's preferred energy source, you can't convert fat into glucose for energy; instead, fatty acids or ketones are used to supply your body with energy from fat. Video of the Day Fat is a concentrated source of energy, and it generally supplies about half the energy you burn daily. During digestion and metabolism, the fat in the food you eat is broken down into fatty acids and glycerol, which are emulsified and absorbed into your blood stream. While some tissues -- including your muscles -- can use fatty acids for energy, your brain can't convert fatty acids to fuel. If you eat more fat than your body needs, the extra is stored in fat cells for later use. Fat has more than twice as many calories per gram as carbs and protein, which makes it an efficient form of stored energy. It would take more than 20 pounds of glycogen -- a type of carbohydrate used for fuel -- to store the same amount of energy in just 10 pounds of fat. Your Body Makes Glucose From Carbs Almost all the glucose in your body originated from carbohydrates, which come from the fruit, vegetables, grains and milk in your diet. When you eat these carb-containing foods, your digestive system breaks them down into glucose, which is then used for energy by your cells. Any excess glucose is converted into glycogen, then stored in your muscles and liver for later use. Once you can't store any more glucose or glycogen, your body stores any leftover carbs as fat. Glucose is your brain's preferred source of energy. However, when glucose is in short supply, your brain can use ketones -- which are derived from fat -- for fuel. Since your brain accounts for approximately one-fifth of your daily calori Continue reading >>
Nutrition Ch. 7
Front Back .Wirisformula{ margin:0 !important; padding:0 !important; vertical-align:top !important;} Metabolism The sum total of all the chemcial reactions that go on in living cells. Energy metabolism includes all the reactions by which the body obtains and spends energy from food. Example: Nutrients provide the body with FUEL and follows them through a series of reactions that release energy from their chemical bonds. As the bonds break, they release energy in a controlled version of the process by which wood burns in a fire. Energy metabolism All of the chemical reactions through which the human body acquires and spends energy from food Anabolism Small compounds joined together to make largers ones; energy must be used in order to do this Ana = up Catabolism Larger compounds BROKEN down into smaller ones; energy is RELEASED kata = down Coupled reactions Energy released from the breakdown of a large compounds is used to drive other reactions ATP Adenosine triphosphate; energy currency of the body -- produced when large compounds are broken down ATP is used to make large compounds from smaller ones. Ribosomes Cellular machinery used to make proteins Mitochondria Where energy is derived from fat, CHO, protein via TCA cycle, electron transport chain Coenzyme Complex organic molecules that work with enzymes to facilitate the enzymes' activity. Many coenzymes have B vitamins as part of their structures. co = with Cofactor The general term for substances that facilitate enzyme action is cofactors; they include both organic coenzymes such as vitamins and inorganic substances such as minerals Enzymes Protein catalysts - proteins that facilitate chemical reactions without being changed in the process Metalloenzyme Enzymes that contain one or more minerals as part of their stru Continue reading >>
Bmbr Metabolic Pathways
All Rights Reserved. All trademarks and copyrights are the property of their respective owners. Simplified metabolic pathways are summarized in this section. For more detailed information, please see any biochemistry textbook or use Biochemistry Animations or The Medical Biochemistry Page . Please note that red indicates molecule is used while green indicates molecule is produced. Glycolysis is responsible for the oxidation of glucose into pyruvate. Pentose phosphate pathway serves several purposes, production of ribose-5-phosphate, NADPH and glycolytic intermediates (fructose and glyceraldehyde-3-phosphate). Glycogenesis and glycogenolysis are processes that synthesize the glucose storage macromolecule glycogen and degrade glycogen into glucose-1-phosphate (and glucose), respectively. Fructose metabolism occurs in muscle and liver. Tricarboxylic acid cycle generates reducing equivalents for the electron transport chain and processes various metabolytes from other pathways. The electron transport chain couples reducing equivalents with ATP production. Gluconeogenesis uses metabolytes to synthesize new glucose. Lipogenesis and lipolysis are processes that synthesize and degrade fatty acids. β-oxidation is responsible for the complete oxidation of fatty acids. This process, which may occur in all cells, involves splitting the 6-carbon monosaccharide into two 2-carbon molecules, dihydroxyacetone phosphate and glyceraldehyde-3-phosphate. Two ATP molecules are invested initially (hexokinase and phosphofructokinase-1) with the eventual net production of 2 ATP molecules (3-phosphoglycerate kinase and pyruvate kinase). Two NADH are produced by glyceraldehyde-3-phosphate dehydrogenase. The resulting NADH may be reoxidized by lactate dehydrogenase such that NAD+ is regener Continue reading >>
Protein Will Not Make You Fat
Here's what you need to know... While it's biochemically possible for protein to turn into fat by ingesting extremely high numbers of calories or extremely large amounts of protein, it's unlikely you'll ever be in that situation. You can pretty much eat as much protein as you want and it won't turn to fat. That old chestnut about only being able to absorb 30 grams of protein in one sitting is bunk. Aside from building muscle, protein provides essential amino acids that serve as the building blocks for other proteins, enzymes, and hormones within the body that are vital for normal functioning. Without this steady supply of amino acids, the body resorts to breaking down its own proteins – typically from muscle – in order to meet this demand. Protein has its share of misconceptions. It's not uncommon to hear claims that dietary protein eaten in excess of some arbitrary number will be stored as body fat. Even those who are supposed to be reputable sources for nutrition information propagate this untenable dogma. While paging through a nutrition textbook I came across a section in the protein chapter regarding amino acids and energy metabolism (1). To quote the book directly: "Eating extra protein during times of glucose and energy sufficiency generally contributes to more fat storage, not muscle growth. This is because, during times of glucose and energy excess, your body redirects the flow of amino acids away from gluconeogenesis and ATP-producing pathways and instead converts them to lipids. The resulting lipids can subsequently be stored as body fat for later use." This is, more or less, supported by another textbook I own (2): "In times of excess energy and protein intakes coupled with adequate carbohydrate intake, the carbon skeleton of amino acids may be used to s Continue reading >>
Gluconeogenesis And Beta-oxiation
Glucogneogenesis Essentially a reversal of glycolysis Pyruvate ïƒ Glucose Requires three irreversible steps of glycolysis to be bypassed Glucose ‘trapping’ The first step in glycolysis Phosphofructokinase The rate limiting step in glycolysis Pyruvate kinase The final step in glycolysis Gluconeogenesis can only occur in the liver Mainly cytoplasmic Glucose 6-phosphatase Reversal of glucose trapping Catalysed by hexokinase/glucokinase Required for release of glucose into the bloodstream Begins with transport of G6P into vesicles of endoplasmic reticulum Special transporter required Hydrolysis of G6P By glucose 6-phosphatase (G6Pase) Glucose goes back into cytoplasm through GLUT-9 Glucose released into blood via GLUT-2 Remember these are very active and [glucose]blood = [glucose]liver G6Pase is increased in activity on starvation Regulated by increased transcription/translation of gene Fructose 1,6 bisphosphatase Reversal of F6P ïƒ F16BP Above reaction stimulated by allosteric effector F26BP F26BP made by PFK-2 F26BP inhibits F16BPase and stimulates PFK So when F26BP is high, glycolysis is favoured Phosphorylation of PFK-2 converts it into F26BPase Thus the amount of F26BP decreases PFK is inhibited and F16BPase increases So when F26BP is low, gluconeogensis is favoured Phosphoryation is catalysed by cAMP-dependant protein kinase Protein kinase A PKA will be active when cAMP is high When glucagon has bound to its receptors on the liver cell membrane F16BPase is activated when glucagon levels are high As in starvation! Gluconeogenesis & Glycolysis When starving glucagon ï‚ ïƒ ï‚ [cAMP] [F2,6BP]  No stimulus for PFK ïƒ no glycolysis No inhibition for F1,6BPase ïƒ favours gluconeogenesis Reverse PEPïƒ pyruvate Glycolytic ste Continue reading >>
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Respiratory Substrates
define the term respiratory substrate; explain the difference in relative energy values of carbohydrate, lipid and protein Hydrogens The more hydrogens, the more ATP is produced in the electron transport chain Some molecules have more hydrogens than others The more hydrogen atoms there are in a respiratory substrate, the more ATP is produced If there are more hydrogen atoms per mole (fixed amount) of substrate, the more oxygen is needed to be the final acceptor Carbohydrates Glucose is the most common substrate for most mammalian cells Animals store glucose as glycogen, and plants as starch Theoretical maximum energy yield for one mole of glucose is 2870 kJ It takes 30.6 kJ to produce 1 mol ATP Respiration of 1 mol glucose should produce nearly 94 mol ATP, but the actual yield is more like 30, as it has an efficiency of 32% Remaining energy used to generate heat Protein Excess amino acids are deaminated (removal of amine group converted to urea) Rest is changed to glycogen or fat Protein is then hydrolysed (split with water) to amino acids which can be respired Some can be converted to pyruvate, or acetate and then is carried to Krebs cycle Some can enter Krebs directly Number of hydrogen atoms per mole accepted by NAD then used in electron transport chain is slightly more than the number of hydrogen atoms per mole of glucose, so proteins release slightly more energy than equivalent masses of glucose Lipids Made of fatty acids and glycerol Glycerol can be converted to glucose, fatty acids can’t Contain many carbons and hydrogens Fatty acids combined with CoA after ATP hydrolysed (split using water) to AMP (adenosine monophosphate) Fatty acid CoA complex taken to matrix and broken down into 2 acetyl groups Reduced NAD and FAD are formed Acetyl groups are released Continue reading >>
Ketosis, Ketones, And How It All Works
Ketosis is a process that the body does on an everyday basis, regardless of the number of carbs you eat. Your body adapts to what is put in it, processing different types of nutrients into the fuels that it needs. Proteins, fats, and carbs can all be processed for use. Eating a low carb, high fat diet just ramps up this process, which is a normal and safe chemical reaction. When you eat carbohydrate based foods or excess amounts of protein, your body will break this down into sugar – known as glucose. Why? Glucose is needed in the creation of ATP (an energy molecule), which is a fuel that is needed for the daily activities and maintenance inside our bodies. If you’ve ever used our keto calculator to determine your caloric needs, you will see that your body uses up quite a lot of calories. It’s true, our bodies use up much of the nutrients we intake just to maintain itself on a daily basis. If you eat enough food, there will likely be an excess of glucose that your body doesn’t need. There are two main things that happen to excess glucose if your body doesn’t need it: Glycogenesis. Excess glucose will be converted to glycogen and stored in your liver and muscles. Estimates show that only about half of your daily energy can be stored as glycogen. Lipogenesis. If there’s already enough glycogen in your muscles and liver, any extra glucose will be converted into fats and stored. So, what happens to you once your body has no more glucose or glycogen? Ketosis happens. When your body has no access to food, like when you are sleeping or when you are on a ketogenic diet, the body will burn fat and create molecules called ketones. We can thank our body’s ability to switch metabolic pathways for that. These ketones are created when the body breaks down fats, creating Continue reading >>
Full Text Of "msqs Biochemistry"
G. Vidya Sagar NEW AGE INTERNATIONAL PUBLISHERS MCQs Biochemistry This page intentionally left blank MCQs in Biochemistry G. Vidya Sagar Director and Principal Veerayatan Institute of Pharmacy Mandvi, Kutch (Gujarat) Dean, Faculty of Pharmaceutical Sciences KSKV Kachchh University Bhuj (Gujarat) NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS New Delhi Bangalore Chennai Cochin Guwahati Hyderabad Jalandhar Kolkata Lucknow Mumbai Ranchi Publishing for one world Visit us at www.newagepublishers.com Copyright 2008, New Age International (P) Ltd., Publishers Published by New Age International (P) Ltd., Publishers All rights reserved. No part of this ebook may be reproduced in any form, by photostat, microfilm, xerography, or any other means, or incorporated into any information retrieval system, electronic or mechanical, without the written permission of the publisher. All inquiries should be emailed to [email protected] ISBN (13) : 978-81-224-2627-4 Publishing for one world NEW AGE INTERNATIONAL (P) LIMITED, PUBLISHERS 4835/24, Ansari Road, Daryaganj, New Delhi - 1 10002 Visit us at www.newagepublishers.com Dedicated to PROF. DR. F.V. MANVI KLE Society, BELGAUM KARNATAKA. "To My First Pharmacy teacher with Love" This page intentionally left blank FOREWORD Competitive Examinations are the order of the day. All Colleges conducting professional courses at PG level are admitting students based on common entrance examination, which is of objective type. In Pharmacy, M .Pharm admissions are based on qualifying the GATE enterance examination conducted by G ovt. of India. In this book, The author has done good work in preparing several objective questions which help the students to face the subjectin the examination with poise and confidence. The book is well balanced and Continue reading >>
Glycolysis And Fatty Acid Oxidation: A Biochemistry Crash Course
Glycolysis and Fatty Acid Oxidation: A Biochemistry Crash Course Glycolysis and Fatty Acid Oxidation: A Biochemistry Crash Course Cells need a constant supply of energy to survive. The biochemical currency for energy is adenosine triphosphate (ATP) and is produced in the mitochondria. But the mitochondria need a fuel source to produce ATP. Cells can use sugars, fats, and amino acids as potential fuel sources. The cell prioritizes the available resources, using glucose first followed by fatty acids, and finally amino acids from protein catabolism. This guide will discuss the processing of glucose and fatty acids into acetyl CoA, the requisite molecule for the Krebs cycle (or citric acid cycle, TCA). The mitochondria take the acetyl CoA and oxygen, and through a series of biochemical reactions to produce ATP and carbon dioxide. This process is known as cellular respiration. For a deeper discussion, refer to the Krebs cycle and citric acid cycle study guides. Glycolysis is the process in which glucose is broken down into a suitable feed stock for the citric acid cycle. When not in demand, the cell stores glucose as a complex carbohydrate called glycogen. When the ATP concentrations drop, the stored glucose is mobilized. Figure 1. Overview of glycolysis. The transformation of glucose to pyruvate. Image Source: Wikimedia Commons Figure 1 outlines the process of glycolysis. The goal of glycolysis is to trap the 6-carbon glucose molecule and break it down into a two pyruvate molecules. When studying this process, you should print out the figures and memorize the structures and names as quickly as possible. Figure 1 provides the abbreviations for each compound, e.g., PEP for phosphoenolpyruvate. You may also be required to know the enzymes associated with each conversion; the Continue reading >>
Tributes To Energy Production By Entering Glycolysis As Dihydroxyacetone Phosphate.
25.6 The Key Intermediate-Acetyl CoA 77t 25.6 The key intermediote-acetyl CoA AIMS: To name the shored intermediote of both carbohydrote ond fotty ocid metobolism, To list four fotes of ocetyl CoA in the liver. Now that we have seen how the body oxidizes fatty acids, we can form an overall picture of the various parts of fatty acid metabolism. We can exam- ine the relationships between carbohydrate metabolism and fatty acid metabolism at the same time. Since the liver conducts more carbohydrate metabolism and fatty acid metabolism than any other organ, this discus- sion will focus on it. Figure 25.4 shows the relationships we will be examining in the remain- der of this chapter. Refer to it often as you read on. The figure shows that Focus Fatty acid metabolism and carbohydrate metabolism intersect at acetyl CoA. Figure 25.4 The major pathways of lipid metab- olism in the liver and their relation- ship to carbohydrate metabolism. Converting carbohydrates to fatty acids is an efficient way to store energy. fatty acids entering the liver from the blood may be reslmthesized into triglycerides and stored in the adipose tissue there. Alternatively, fatty acids may be broken do',nm to aceryl CoA. Glucose is also broken do',nm to acetyl CoA. If you are beginning to suspect that aceryl CoA must be a key com- pound in the metabolic interplay between carbohydrate and fatty acid metabolism, you are certainly correct. Four possible fates await the acetyl CoA produced from fatty acids or glucose in the liver: 1. The acetyl CoA in the mitochondria may be oxidized to carbon dioxide and water in the citric acid cycle and respiration. This pathway, which is used if the liver cells need to generate energy through respiration, makes it clear that the citric acid cycle is shared by both gl Continue reading >>
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 >>
Lipid Metabolism
Apart from two polyunsaturated fatty acids (linoleic acid, C18:2; and alpha-linolenic acid, C18:3) the human body is able to synthesize all other fatty acids required either for structural lipids in membranes or for storage purpose. Fatty acid synthesis and their further use for phospholipids and triglycerides is referred to as lipogenesis. Any metabolite that yields acetyl-CoA during its degradation is a potential supplier for lipogenesis, the most important being carbohydrates. In general, it can be understood that excess carbohydrates beyond the body's energy needs will be converted into fat. Lipogenesis is not a simple reversal of beta oxidation, but uses an entirely different pathway for the regeneration of fatty acids from acetyl-CoA precursors. The reductive synthesis of fatty acids is a cytoplasmic process carried out by a multienzyme complex called the acyl carrier protein (ACP). The acyl chain is covalently linked to the sulfhydryl prosthetic group of ACP. The reduction-oxidation steps require NADPH (rather than FADH2 and NADH found during beta-oxidation). There are three major processes involved in the reductive synthesis of fatty acids. First, acetyl-CoA has to be transported across the inner mitochondrial membrane into the cytoplasm. Second, the true substrate for ACP is malonyl-CoA, a C3 acyl thioester that is formed by the carboxylation of acetyl-CoA to malonyl-CoA. Third, the first end product and intermediate for further lipid biosynthesis is palmitic acid, the C16 acyl derivative. For all other lipogenetic processes, protein complexes other than ACP are required. Fatty acid synthesis is a cytoplasmic process. All acetyl-CoA must be exported from the mitochondrial matrix via citrate (first step in Krebs cycle). In the cytoplasm, citrate is split into a Continue reading >>
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