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Glucose Galactose Disaccharide

Carbohydrates

Carbohydrates

Carbohydrates have the general molecular formula CH2O, and thus were once thought to represent "hydrated carbon". However, the arrangement of atoms in carbohydrates has little to do with water molecules. Starch and cellulose are two common carbohydrates. Both are macromolecules with molecular weights in the hundreds of thousands. Both are polymers (hence "polysaccharides"); that is, each is built from repeating units, monomers, much as a chain is built from its links. The monomers of both starch and cellulose are the same: units of the sugar glucose. Sugars Monosaccharides Three common sugars share the same molecular formula: CHO. Because of their six carbon atoms, each is a hexose. They are: glucose, "blood sugar", the immediate source of energy for cellular respiration galactose, a sugar in milk (and yogurt), and fructose, a sugar found in honey. Although all three share the same molecular formula (C6H12O6), the arrangement of atoms differs in each case. Substances such as these three, which have identical molecular formulas but different structural formulas, are known as structural isomers. Glucose, galactose, and fructose are "single" sugars or monosaccharides. Two monosaccharides can be linked together to form a "double" sugar or disaccharide. Disaccharides Three common disaccharides: sucrose — common table sugar = glucose + fructose lactose — major sugar in milk = glucose + galactose maltose — product of starch digestion = glucose + glucose Although the process of linking the two monomers is rather complex, the end result in each case is the loss of a hydrogen atom (H) from one of the monosaccharides and a hydroxyl group (OH) from the other. The resulting linkage between the sugars is called a glycosidic bond. The molecular formula of each of these disacchar Continue reading >>

Types Of Sugar

Types Of Sugar

There are several types of sugar. This page mentions some specific sugars but concentrates on the main categories of sugars (monosaccharides and disaccharides) and the relationship between these and certain larger carbohydrates. What is Sugar ? Definition of sugar : A sugar is a carbohydrate that is soluble in water. Sugars are usually crystalline and have a sweet taste. Chemicals that are sugars often have names ending in "-ose". For example, note the suffix "-ose" in fructose, glucose, galactose, sucrose, lactose, and maltose. The word-ending "-saccharide" does not necessarily indicate that the chemical or group or category of chemicals is a sugar. See more examples of prefixes and suffixes used in biology - general biology, not all medical terms. The two main categories of sugars are monosaccharides and disaccharides. They are often described together with polysaccharides, and sometimes also oligosaccarides, due to the chemical relationship between these types of carbohydrates: Categories of sugars: Monosaccharides are simple ("unit") sugars. Disaccharides consist of molecules whose form is that of two monosaccharide molecules joined together. Categories of larger carbohydrate molecules formed from sugars: Oligosaccharides consist of molecules formed from a few (i.e. more than 2, but not "many") monosaccharide molecules joined together. Polysaccharides consist of molecules formed from many monosaccharide molecules attached together in the form of long chains. Courses covering the human digestive system and human diet and nutrition often include the following information about: Monosaccharides Disaccharides Oligosaccharides, and Polysaccharides 1. Monosaccharides Chemical Structure: Monosaccharides are also called "simple sugars". Monosaccharides are the common base u Continue reading >>

Disaccharide | Biochemistry | Britannica.com

Disaccharide | Biochemistry | Britannica.com

Disaccharide, also called double sugar, any substance that is composed of two molecules of simple sugars ( monosaccharides ) linked to each other. Disaccharides are crystalline water-soluble compounds . The monosaccharides within them are linked by a glycosidic bond (or glycosidic linkage), the position of which may be designated - or - or a combination of the two (-,-). Glycosidic bonds are cleaved by enzymes known as glycosidases. The three major disaccharides are sucrose , lactose , and maltose. In the bacterium Escherichia coli, energy is derived from the metabolism of disaccharide and oligosaccharide sugars and other small molecules. Sucrose, which is formed following photosynthesis in green plants, consists of one molecule of glucose and one of fructose bonded via an -,-linkage. Lactose (milk sugar), found in the milk of all mammals , consists of glucose and galactose connected by a -linkage. Maltose , a product of the breakdown of starches during digestion, consists of two molecules of glucose connected via an -linkage. Another important disaccharide, trehalose , which is found in single-celled organisms and in many insects , also consists of two molecules of glucose and an -linkage, but the linkage is distinct from the one found in maltose. Continue reading >>

List Of Types Of Disaccharides

List Of Types Of Disaccharides

Disaccharides are sugars or carbohydrates made by linking two monosaccharides . This occurs via a dehydration reaction and a molecule of wateris removed for each linkage. A glycosidic bond can form between any hydroxyl group on the monosaccharide, so even if the two subunits are the same sugar, there are many different combinations of bonds and stereochemistry, producing disaccharides with unique properties. Depending on the component sugars, disaccharides may be sweet, sticky, water-soluble, or crystalline. Both natural and artificial disaccharides are known. Here is a list of some disaccharides, including the monosaccharides they are made from and foods containing them. Sucrose, maltose, and lactose are the most familiar disaccharides, but there are others. Sucrose is table sugar. It is purified from sugar cane or sugar beets. Maltose is a sugar found in some cereals and candies. It is a product of starch digestions and may be purified from barley and other grains. Lactose is a disaccharide found in milk. It has the formulaC12H22O11 and is an isomer of sucrose. Lactulose is a synthetic (man-made) sugar that is not absorbed by the bodybut is broken down in the colon into products that absorb water into the colon, thus softening stools. Its primary use is to treat constipation. It is also used to reduce blood ammonia levels in persons with liver diseasesince lactulose absorbs ammonia into the colon (removing it from the body). Trehalose is also known as tremalose or mycose. It is a natural alpha-linked disaccharide with extremely high water retention properties. In nature, it helps plants and animals reduce long periods without water. Cellobiose is a hydrolysis product of cellulose or cellulose-rich materials, such as paper or cotton. It is formed by linking two beta-g Continue reading >>

Disaccharides And Polysaccharides

Disaccharides And Polysaccharides

- [Voiceover] All right. In a previous video, I talked about how cyclic monosaccharides, like this green cyclic glucose, can react with alcohols, like this pink alcohol, to form acetals and ketals. I believe that I mentioned that sometimes the alcohol that comes in and is reduced is actually another carbohydrate. Let me draw this in here. It makes sense, because what you see, with carbohydrates, is that they're chock full of hydroxilate groups. They're chock full of these OH groups. So, really, they can function really similarly to alcohol in reactions. When this happens, the individual monosaccharides are linked together to make an acetal. We call this linkage a glycosidic linkage. This is a glycosidic, a glycosidic linkage. Now, when two monosaccharides are linked together in this fashion, by glycosidic linkages, we call the product a disaccharide. A disaccharide. We have "di," which means two, and "saccharide," which means sugar. So sugar. So two monosaccharides linked together, they're called a disaccharide. Now, with disaccharides, most commonly the glycosidic linkage forms between the anomaric carbon, or C1 ... Remember, this is the anomeric carbon. That's C1. Over in our glycosite here, it'd be right here, just the same, we got C1 of the first sugar. Then, C4 of the second sugar, so right here would be C4, and it's just the same over here. So right here we have C4. That's the second sugar. So we call this a one, four glycosidic linkage. Then, just like we could further break down our monosaccharides into alpha and beta based off the orientation of the anomeric hydroxyl group, we can more specifically call the one, four linkage an alpha or a beta linkage, again, based off what is now the orientation of the OR group on the anomeric carbon. Same rules apply. If the Continue reading >>

Help Us Do More

Help Us Do More

What’s in a spud? Besides water, which makes up most of the potato’s weight, there’s a little fat, a little protein…and a whole lot of carbohydrate (about 37 grams in a medium potato). Some of that carbohydrate is in the form of sugars. These provide the potato, and the person eating the potato, with a ready fuel source. A bit more of the potato's carbohydrate is in the form of fiber, including cellulose polymers that give structure to the potato’s cell walls. Most of the carbohydrate, though, is in the form of starch, long chains of linked glucose molecules that are a storage form of fuel. When you eat French fries, potato chips, or a baked potato with all the fixings, enzymes in your digestive tract get to work on the long glucose chains, breaking them down into smaller sugars that your cells can use. Carbohydrates are biological molecules made of carbon, hydrogen, and oxygen in a ratio of roughly one carbon atom (C) to one water molecule (H​O). This composition gives carbohydrates their name: they are made up of carbon (carbo-) plus water (-hydrate). Carbohydrate chains come in different lengths, and biologically important carbohydrates belong to three categories: monosaccharides, disaccharides, and polysaccharides. In this article, we’ll learn more about each type of carbohydrates, as well as the essential energetic and structural roles they play in humans and other organisms. If the sugar has an aldehyde group, meaning that the carbonyl C is the last one in the chain, it is known as an aldose. If the carbonyl C is internal to the chain, so that there are other carbons on both sides of it, it forms a ketone group and the sugar is called a ketose. Sugars are also named according to their number of carbons: some of the most common types are trioses (thre Continue reading >>

Complex Carbohydrates Are Formed By Linkage Of Monosaccharides

Complex Carbohydrates Are Formed By Linkage Of Monosaccharides

Because sugars contain many hydroxyl groups, glycosidic bonds can join one monosaccharide to another. Oligosaccharides are built by the linkage of two or more monosaccharides by O-glycosidic bonds (Figure 11.10). In maltose, for example, two d-glucose residues are joined by a glycosidic linkage between the α-anomeric form of C-1 on one sugar and the hydroxyl oxygen atom on C-4 of the adjacent sugar. Such a linkage is called an α-1,4-glycosidic bond. The fact that monosaccharides have multiple hydroxyl groups means that various glycosidic linkages are possible. Indeed, the wide array of these linkages in concert with the wide variety of monosaccharides and their many isomeric forms makes complex carbohydrates information-rich molecules. Go to: 11.2.1. Sucrose, Lactose, and Maltose Are the Common Disaccharides A disaccharide consists of two sugars joined by an O-glycosidic bond. Three abundant disaccharides are sucrose, lactose, and maltose (Figure 11.11). Sucrose (common table sugar) is obtained commercially from cane or beet. The anomeric carbon atoms of a glucose unit and a fructose unit are joined in this disaccharide; the configuration of this glycosidic linkage is α for glucose and β for fructose. Sucrose can be cleaved into its component monosaccharides by the enzyme sucrase. Lactose, the disaccharide of milk, consists of galactose joined to glucose by a β-1,4-glycosidic linkage. Lactose is hydrolyzed to these monosaccharides by lactase in human beings (Section 16.1.12) and by β-galactosidase in bacteria. In maltose, two glucose units are joined by an α-1,4 glycosidic linkage, as stated earlier. Maltose comes from the hydrolysis of starch and is in turn hydrolyzed to glucose by maltase. Sucrase, lactase, and maltase are located on the outer surfaces of epith Continue reading >>

Glucose-galactose Malabsorption - Genetics Home Reference

Glucose-galactose Malabsorption - Genetics Home Reference

Glucose-galactose malabsorption is a condition in which the cells lining the cannot take in the sugars glucose and galactose, which prevents proper digestion of these molecules and larger molecules made from them. Glucose and galactose are called simple sugars, or monosaccharides. Sucrose (table sugar) and lactose (the sugar found in milk) are called disaccharides because they are made from two simple sugars, and are broken down into these simple sugars during digestion. Sucrose is broken down into glucose and another simple sugar called fructose, and lactose is broken down into glucose and galactose. As a result, lactose, sucrose and other compounds made from sugar molecules (carbohydrates) cannot be digested by individuals with Glucose-galactose malabsorption generally becomes apparent in the first few weeks of a baby's life. Affected infants experience severe diarrhea resulting in life-threatening dehydration, increased acidity of the blood and tissues (acidosis), and weight loss when fed breast milk or regular infant formulas. However, they are able to digest fructose-based formulas that do not contain glucose or galactose. Some affected children are better able to tolerate glucose and galactose as they get older. Small amounts of glucose in the urine (mild glucosuria) may occur intermittently in this disorder. Affected individuals may also develop kidney stones or more widespread deposits of calcium within the kidneys. SLC5A1 gene provides instructions for producing a sodium/glucose cotransporter protein called SGLT1. This protein is found mainly in the intestinal tract and, to a lesser extent, in the kidneys, where it is involved in transporting glucose and the structurally similar galactose across cell membranes. The sodium/glucose cotransporter protein is impor Continue reading >>

Principles Of Biochemistry/the Carbohydrates: Monosaccharides, Disaccharides And Polysaccharides

Principles Of Biochemistry/the Carbohydrates: Monosaccharides, Disaccharides And Polysaccharides

Principles of Biochemistry/The Carbohydrates: Monosaccharides, Disaccharides and Polysaccharides From Wikibooks, open books for an open world Earlier the name "carbohydrate" was used in chemistry for any compound with the formula Cm(H2O)n. Following this definition, some chemists considered formaldehyde CH2O to be the simplest carbohydrate, while others claimed that title for glycolaldehyde. Today the term is generally understood in the biochemistry sense, which excludes compounds with only one or two carbons. Natural saccharides are generally built of simple carbohydrates called monosaccharides with general formula (CH2O)n where n is three or more. A typical monosaccharide has the structure H-(CHOH)x(C=O)-(CHOH)y-H, that is, an aldehyde or ketone with many hydroxyl groups added, usually one on each carbon atom that is not part of the aldehyde or ketone functional group . Examples of monosaccharides are glucose , fructose, and glyceraldehyde. However, some biological substances commonly called "monosaccharides" do not conform to this formula (e.g., uronic acids and deoxy-sugars such as fucose ), and there are many chemicals that do conform to this formula but are not considered to be monosaccharides (e.g., formaldehyde CH2O and inositol (CH2O)6). The open-chain form of a monosaccharide often coexists with a heterocyclic compound|closed ring form where the aldehyde / ketone carbonyl group carbon (C=O) and hydroxyl group (-OH) react forming a hemiacetal with a new C-O-C bridge. Monosaccharides can be linked together into what are called polysaccharides (or oligosaccharides) in a large variety of ways. Many carbohydrates contain one or more modified monosaccharide units that have had one or more groups replaced or removed. For example, deoxyribose, a component of DNA, is Continue reading >>

Chapter 4 Flashcards | Quizlet

Chapter 4 Flashcards | Quizlet

any sugars that are not broken down during digestion and have the general formula CnH2nO What monosaccharide is predominantly found in the blood? two monosaccharides chemically joined by a process called condensation What monosaccharide makes up each of the disaccharides? sucrose- one molecule of glucose and one molecule o fructose lactose- one molecule of glucose and one molecule of galactose Do we find it in foods as glucose? If not in which form do we consume it? not seen as monosaccharide in food but joins to other other sugars to form disaccharides, starch, and dietary occurs naturally in fruits and vegetables Do we find it in foods as galactose? If not in which form do we consume it? No. usually is chemically bonded to glucose to form lactose, the primary sugar in milk Define sugar alcohols and list the names of them? Where are they found in the food supply. compounds formed from monosaccharides by replacing a hydrogen atom with a hydroxyl group (-OH); commonly used as a nutritive sweetener.some fruits naturally contain them, breath mints, candy, sugarless gum Alpha bonds: What are they, were do we find them and are they easy to break during digestion chemical bonds linking two monosaccharides that can be broken by human intestinal enzymes, releasing individual monosaccharide, found in maltose and sucrose Beta bonds: What are they, were do we find them and are they easy to break during digestion chemical bonds linking two monosaccharides that cannot be broken by human intestinal enzymes, found in cellulose Sucrose: what category of CHO, where is it found in the food supply and what enzyme digests it disaccharide, most familiar to us as table sugar, natural sweetness of honey, maple syrup, fruits, and vegetables Lactose: what category of CHO, where is it found in Continue reading >>

Carbohydrates

Carbohydrates

Carbohydrate Molecules Carbohydrates are essential macromolecules that are classified into three subtypes: monosaccharides, disaccharides, and polysaccharides. Learning Objectives Describe the structure of mono-, di-, and poly-saccharides Key Takeaways Key Points Monosaccharides are simple sugars made up of three to seven carbons, and they can exist as a linear chain or as ring-shaped molecules. Glucose, galactose, and fructose are monosaccharide isomers, which means they all have the same chemical formula but differ structurally and chemically. Disaccharides form when two monosaccharides undergo a dehydration reaction (a condensation reaction); they are held together by a covalent bond. Sucrose (table sugar) is the most common disaccharide, which is composed of the monomers glucose and fructose. A polysaccharide is a long chain of monosaccharides linked by glycosidic bonds; the chain may be branched or unbranched and can contain many types of monosaccharides. Key Terms isomer: Any of two or more compounds with the same molecular formula but with different structure. dehydration reaction: A chemical reaction in which two molecules are covalently linked in a reaction that generates H2O as a second product. biopolymer: Any macromolecule of a living organism that is formed from the polymerization of smaller entities; a polymer that occurs in a living organism or results from life. Carbohydrates can be represented by the stoichiometric formula (CH2O)n, where n is the number of carbons in the molecule. Therefore, the ratio of carbon to hydrogen to oxygen is 1:2:1 in carbohydrate molecules. The origin of the term “carbohydrate” is based on its components: carbon (“carbo”) and water (“hydrate”). Carbohydrates are classified into three subtypes: monosaccharides, dis Continue reading >>

Sugars: The Difference Between Fructose, Glucose And Sucrose

Sugars: The Difference Between Fructose, Glucose And Sucrose

29/06/2016 7:43 AM AEST | Updated 15/07/2016 12:56 PM AEST Sugars: The Difference Between Fructose, Glucose And Sucrose We're not just confused, we're also misinformed. "Fructose is the worst for you." "No way, sucrose is the devil." "I don't eat any sugar." Sugar is confusing. While some people only use certain types of sugars, others dismiss them completely. But is this necessary, or even grounded? To help settle the confusion, we spoke to Alan Barclay -- accredited practising dietitian, spokesperson for the Dietitians Association of Australia and Chief Scientific Officer at the Glycemic Index Foundation . "All the sugars are used as a source of fuel, but there are subtle differences in the way they are digested and absorbed," Barclay said. "In foods in Australia, the most common sugars are monosaccharides (glucose, fructose and galactose), but mostly these are occurring as disaccharides (which are sucrose, lactose and maltose)." Monosaccharides and disaccharides are two kinds of simple sugars, which are a form of carbohydrate. Oligosaccharides and polysaccharides, on the other hand, contain more sugar combinations and are known as complex carbohydrates -- for example, whole grain breads, brown rice and sweet potatoes. Monosaccharides require the least effort by the body to break down, meaning they are available for energy more quickly than disaccharides. "Monosaccharides don't require any digestion and can be absorbed into the mouth," Barclay said. "The problem there is they can cause dental caries which is one of the primary reasons why we need to be careful of how much added sugar we're consuming." Glucose -- the body's main source of energy and is found in fruit such as pasta, whole grain bread, legumes and a range of vegetables. Fructose -- this 'fruit sugar' fo Continue reading >>

Why Is Ribose Not A Dietary Consideration

Why Is Ribose Not A Dietary Consideration

Carbohydrates Structures and Function Simple sugars: monosaccharides, disaccharides, oligosaccharides) Complex sugar: polysaccharides (starch and fiber) Monosaccharides (glucose, fructose, and galactose – isomers of each other) Glucose (also called dextrose and blood sugar) has a six carbon (hexose) ring structure Fructose (also called levulose) has a six carbon ring structure Found in fruit, honey, and corn syrup used in soft drink and food production 8 to 10% of our energy intake Metabolized into glucose in the liver Converted into glycogen, lactic acid, or fat if consumption is high Galactose has a six carbon ring structure Not usually found in nature but exists mostly as a unit of the disaccharide lactose which is found in nature Converted to glucose in the liver or stored as glycogen Ribose has a five carbon ring structure and used in genetic material (?) Oligosaccharides Raffinose (trisaccharide - made up of glucose, fructose, and galactose) Stachyose (tetrasaccharide - made up of a glucose, fructose, and two galactose) Bacteria in the large intestines break apart these oligosaccharides, producing gas and other byproducts Complex Cabohydrates (Digestible starch and glycogen and indigestible fiber) Starch Amylose is a straight chain polymer Amylopectin is a branched chain polymer Amylopectin raises blood sugar levels quicker because of the branched configuration which enables more digestive capabilities Fiber Dietary fibers also composed of the non-carbohydrate called lignin All dietary fibers come from plants and are not digested in the stomach But fibers can be soluble and insoluble in water Those that are soluble include pectins, gums, and mucilages and are metabolized by bacteria in the intestines Carbohydrate Digestion and Absorption Begins in the mouth (sal Continue reading >>

Disaccharide

Disaccharide

Sucrose, a disaccharide formed from condensation of a molecule of glucose and a molecule of fructose A disaccharide (also called a double sugar or biose[1]) is the sugar formed when two monosaccharides (simple sugars) are joined by glycosidic linkage. Like monosaccharides, disaccharides are soluble in water. Three common examples are sucrose, lactose,[2] and maltose. Disaccharides are one of the four chemical groupings of carbohydrates (monosaccharides, disaccharides, oligosaccharides, and polysaccharides). The most common types of disaccharides—sucrose, lactose, and maltose—have twelve carbon atoms, with the general formula C12H22O11. The differences in these disaccharides are due to atomic arrangements within the molecule.[3] The joining of simple sugars into a double sugar happens by a condensation reaction, which involves the elimination of a water molecule from the functional groups only. Breaking apart a double sugar into its two simple sugars is accomplished by hydrolysis with the help of a type of enzyme called a disaccharidase. As building the larger sugar ejects a water molecule, breaking it down consumes a water molecule. These reactions are vital in metabolism. Each disaccharide is broken down with the help of a corresponding disaccharidase (sucrase, lactase, and maltase). Classification[edit] There are two functionally different classes of disaccharides: Reducing disaccharides, in which one monosaccharide, the reducing sugar of the pair, still has a free hemiacetal unit that can perform as a reducing aldehyde group; cellobiose and maltose are examples of reducing disaccharides, each with one hemiacetal unit, the other occupied by the glycosidic bond, which prevents it from acting as a reducing agent. Non-reducing disaccharides, in which the component mo Continue reading >>

Disaccharide - Definition, Function And Examples | Biology Dictionary

Disaccharide - Definition, Function And Examples | Biology Dictionary

A disaccharide, also called a double sugar, is a molecule formed by two monosaccharides, or simple sugars. Three common disaccharides are sucrose, maltose, and lactose. They have 12 carbon atoms, and their chemical formula is C12H22O11. Other, less common disaccharides include lactulose, trehalose, and cellobiose. Disaccharides are formed through dehydration reactions in which a total of one water molecule is removed from the two monosaccharides. Disaccharides are carbohydrates found in many foods and are often added as sweeteners. Sucrose, for example, is table sugar, and it is the most common disaccharide that humans eat. It is also found in other foods like beetroot. When disaccharides like sucrose are digested, they are broken down into their simple sugars and used for energy. Lactose is found in breast milk and provides nutrition for infants. Maltose is a sweetener that is often found in chocolates and other candies. Plants store energy in the form of disaccharides like sucrose and it is also used for transporting nutrients in the phloem. Since it is an energy storage source, many plants such as sugar cane are high in sucrose. Trehalose is used for transport in some algae and fungi. Plants also store energy in polysaccharides, which are many monosaccharides put together. Starch is the most common polysaccharide used for storage in plants, and it is broken down into maltose. Plants also use disaccharides to transport monosaccharides like glucose, fructose, and galactose between cells. Packaging monosaccharides into disaccharides makes the molecules less likely to break down during transport. When disaccharides are formed from monosaccharides, an -OH (hydroxyl) group is removed from one molecule and an H (hydrogen) is removed from the other. Glycosidic bonds are for Continue reading >>

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