Chemistry of carbonhydrates. Flashcards

Question

What is Sialic acid?

Answer 1

An N-acyl or O-acyl derivative of neuraminic acid.

Answer 2

N-acetyl Neuraminic acid (NANA)

Answer 3

Both Glycoprotein and Ganglioside

Answer 4

Refer to drawing 5 in booklet

Answer 5

Furanose ring (Fructofuranose)

Answer 6

Pyranose ring (Glucopyranose)

Answer 7

Refer to drawing 6 in booklet

Answer 8

Fruit juice, honey, sugarcane, seminal fluid

Answer 9

[Cn(H2O)n-1

Answer 10

They are crystalline, soluble and sweet to taste and are basically 2 monosaccharide linked by a glycosidic bond. They will release 2 monosaccharides on hydrolysis.

Answer 11

NonReducing disaccharides (the functional groups are involved in the glycosidic bond are thus not free) Reducing Disaccharides (Free functional group)

Answer 12

Maltose, Isomaltose, Lactose, Lactulose

Answer 13

Sucrose, Trelahose

Answer 14

aDglucose+aDglucose

Answer 15

aDglucose+aDglucose

Answer 16

D Galactose+ bD glucose, (b1-b4 linkage)

Answer 17

aD Galactose+ bD Fructose

Answer 18

(a1- a4 linkage)

Answer 19

a1-a6 linkage

Answer 20

b1-b4 linkage

Answer 21

a1-b4 linkage

Answer 22

sugar of insect hemolymph, yeast and fungi

Answer 23

aDglucose + aDglucose

Answer 24

aDglucose + aDglucose

Answer 25

aDglucose + bD Fructose

Answer 26

a1-b2 linkage

Answer 27

a1-a1 linkage

Answer 28

Osmotic sedative Not hydrolyzed but fermented by intestinal bacteria Mainly synthetic (small amounts in heated milk)

Answer 29

carbonhydrates with 3-10 monosaccharide units

Answer 30

Oligosaccharides

Answer 31

Proteins (Glycoproteins and Proteoglycans) and Lipids (Glycolipids)

Answer 32

Carbs with > 10 monosaccharide chains

Answer 33

Homoglycans (Homopolysaccharides) and Heteroglycans (Heteropolysaccharides)

Answer 34

Carbonhydrates with 1 type of monosacchararide

Answer 35

Carbohydrates with 2 or more types of monosaccharides

Answer 36

Glycogen, cellulose, dextran, inulin(fructosan), starch, chitin.

Answer 37

Glycosaminoglycans(Mucopolysaccharides), Pectin, agarose, agar

Answer 38

starch, glycogen

Answer 39

amylose(13-20%) and amylopectin(80-87%)

Answer 40

soluble unbranched chain, with a1-4 glycosidic linkage

Answer 41

insoluble branched chain with a1-4 glycosidic linkage and a1-6 glycosidic linkage (at branches)

Answer 42

Dextrin is a short chain polysaccharide formed by the partial hydrolysis of starch by aAmylase (enzyme). They have free aldehyde groups. It occurs in honey and is not fermented by yeast. They are used in food additives, textiles, adhesives, thickness and stabilizers.

Answer 43

Dextran is a long chain polysaccharide (glycosidic linkages: a1-6,a1-4 and a1-3) produced by certain bacteria and used as a plasma volume expander in the treatment of shock. It is essentially called a Plasma Expnder. It is used as a dietary fiber supplement and a food thickner.

Answer 44

They are high molecular weight substances that exert osmotic pressure and maintain food in the vascular component.

Answer 45

Human albumin dextran hydroxyethyl starch degraded gelatin polymer

Answer 46

made up of aDglucose. It has a1-4 glycosidic linkage at the linear chain and a1-6 glycosidic linkage at the branches

Answer 47

Muscle glycogen is a storage form of energy within the muscles itself Liver glycogen is important for the maintenance of blood glucose.

Answer 48

exoskeletons of insects and crustaceans, and in mushrooms

Answer 49

Made up of N acetyl Glucosamine joined by b1-4 linkage

Answer 50

It is an insoluble unbranched polymer of bDglucose and consists of b1-4 glycosidic linkage. Humans cannot digest cellulose because we don't have the enzyme that digests it, unlike herbivores

Answer 51

Cellulose is associated with the reduced incidence of: Cardiovascular disease, colon cancer, diverticulosis, diabetes Cellulose is a dietary fiber used in the bulk of food. It aids intestinal motility, and helps produce smooth stool.

Answer 52

A fructose homopolysaccharide of b2-1 glycosidic linkage. It is readily soluble in water.

Answer 53

dahlias, chicoris, garlics, dandelions, onions

Answer 54

INULINASE (not available in humans)

Answer 55

Used in clearance test to determine Glomerular filtration rate.

Answer 56

They are unbranched heteropolysaccharide chains composed of disaccharide repeat units. Each unit is composed of amino sugar (D-glucosamine or D-galactosamine) and uronic acid(L-glucuronic acid or its epimer L-iduronic acid.) I.e except in the case of keratan sulphate. This polymer is attached covalently to extracellular proteins called core protein (except hyaluronicacid) to form proteoglycans resulting in a structure that resembles a “bottle brush”. The proteoglycan monomer associates with a molecule of hyaluronic acid to form proteoglycan aggregates.The association is stabilized by additional small proteins called link proteins. With the exception of hyaluronic acid, all the GAGs contain sulfate group. The amount of carbs in proteoglycans>Glycoproteins

Answer 57

They were first isolated from mucin

Answer 58

Refer to drawing 7 in booklet.

Answer 59

Vitreous humor, Synovial fluid of joints, arterial walls, Bones,

Answer 60

D-glucosamine or D-galactosamine

Answer 61

L-glucuronic acid or its epimer L-iduronic acid

Answer 62

They are major components of the extracellular matrix or ground substance. GAGs carry sulfate and carboxyl groups which give them a negative charge and have special ability to bind large amounts of water, thereby producing a gel-like matrix which functions as a cushion against mechanical shocks. They act as “molecular sieves”, determining which substances enter and leave cells. They also give resilience (elasticity) to cartilage, permitting compression and re-expansion. They lubricate joints both at the surface of cartilage and in synovial fluid. The viscous lubricating properties of mucous secretions are also due to the presence of glycosaminoglycans,

Answer 63

Heparin, Condroitin sulphate, Heparin sulphate, Hyaluronic acid, Dermatan sulphate, Keratan sulphate.

Answer 64

N-Acetyl glucosamine -Glucuronic acid

Answer 65

N-Acetyl-galactosamine-Glucuronic acid

Answer 66

N-Acetyl-glucosamine-Galactose

Answer 67

Glucosamine-Glucuronic acid or Iduronic acid

Answer 68

Glucosamine-Glucuronic acid or Iduronic acid

Answer 69

N-Acetyl-galactosamine-L-lduronic acid

Answer 70

keratan sulphate

Answer 71

hyaluronic acid

Answer 72

hyaluronic acid

Answer 73

hyaluronic acid

Answer 74

chondroitin sulphate

Answer 75

E.R and Golgi body

Answer 76

bottle brush

Answer 77

hyaluronic acid

Answer 78

hyaluronic acid and chondroitin sulphate

Answer 79

Dermatan sulphate and Keratan sulphate

Answer 80

Heparan sulphate

Answer 81

Heparan sulphate in synaptic vesicles and Heparin in mast cells

Answer 82

Serves as lubricant and shock absorber, facilitates cell migration in embryogenesis, morphogenesis, wound healing

Answer 83

Serves as an anticoagulant, causes release of lipoprotein lipase from capillary walls

Answer 84

Component of plasma membrane where it may act as receptor and may also participate in the mediation of cell growth, cell-to-cell communication

Answer 85

Transparency of cornea

Answer 86

Transparency of cornea and maintains the overall shape of the eye

Answer 87

Provides an endoskeletal structure helping to maintain their shape. Has a role in compressibility of cartilage in weight bearing

Answer 88

Mast cells, Liver, lung, skin

Answer 89

Skin, Kidney basement membrane

Answer 90

Cartilage, bone, CNS

Answer 91

Skin, Synovial fluid, bone, cartilage, vitreous humor,loose connective tissue, umbilical cord.

Answer 92

Cornea, Cartilage, Loose connective tissue

Answer 93

Glycoproteins are proteins to which oligosaccharides are covalently attached to their polypeptide chain.Glycoproteins contain much shorter carbohydrate chain than proteoglycans.

Answer 94

PROTEOGLYCANS are made of over 95% carbonhydrates. They have long unbranched oligosaccharides and they have repeating units of disaccharide. WHILE GLYCOPROTEINS are made of less than 4% carbohydrates, they have short highly branched oligosaccharides and they do not have repeating units of disaccharides

Answer 95

GAGs are covalently attached to a protein (termed Core Protein) to form hybrid molecules, called Proteoglycan. Proteoglycan molecules attached to core protein forming proteoglycan monomer. The shape of Proteoglycan monomers is Bottle brush. Several Proteoglycan monomer associate noncovalently to a Hyaluronic Acid by a link protein to form Proteoglycan Aggregate

Answer 96

1. Action of Strong Acids: Furfural formation 2. Action of Alkalies: Enolization 3. Oxidation: Sugar acid formation 4. Reduction: Sugar alcohol formation 5. Action of phenylhydrazine: Osazone formation.

Answer 97

On heating a sugar with mineral acids (H2SO4 or HCI), the sugar loses water and forms furfural derivatives. These may condense with α-naphthol, thymol or resorcinol to produce colored complexes. This is the basis of the: * Molisch’s test * Seliwanoff’s test * Bial’s test * Tollen’s-phloroglucinol-HCI test.

Answer 98

On treatment with dilute aqueous alkalies, both aldoses and ketoses are changed to enediols. Enediol is the enol form of sugar because two OH groups are attached to the double bonded carbon. (Benedict and Fehlings test)

Answer 99

When aldoses oxidize under proper conditions they may form: – Aldonic acid – Saccharic acids – Uronic acid

Answer 100

Both aldoses and ketoses may be reduced by enzymes or non-enzymatically to the corresponding polyhydroxy alcohols.

Answer 101

D-sorbitol

Answer 102

D-mannitol

Answer 103

D-mannitol + D-sorbitol

Answer 104

D-dulcitol

Answer 105

Osazones are yellow or orange crystalline derivatives of reducing sugars with phenylhydrazine and have a characteristic crystal structure, which can be used for identification and characterization of different sugars having closely similar properties (like maltose and lactose).

Answer 106

– Glucosazone are needle shaped – Lactosazone are powder puff or tennis ball shaped – Maltosazone are sunflower shaped.

Answer 107

Glycosides are formed when the hydroxyl group of anomeric carbon of a monosaccharide reacts with OH or NH group of second compound that may or may not be a carbohydrate. The bond so formed is known as glycosidic or glycosyl bond. The monosaccharides are joined by glycosidic bonds to form disaccharides, oligosaccharides and polysaccharides. In disaccharides, the glycosidic linkage may be either α or β depending on the configuration of the atom attached to the anomeric carbon of the sugar

Answer 108

Glycosides are found in many drugs, e.g. in antibiotic streptomycin. Cardiac glycosides such as Ouabain and digoxin increase heart muscle contraction and are used for treatment of congestive heart failure Anthracycline glycosides (daunorubicin and doxirubicin), Daunorubicin is used to treat leukemia. Doxirubicin is used to treat a wide range of cancers.

Answer 109

Monosaccharides whose structure cannot be represented by general formula or which have some unusual features

Answer 110

* Phosphoric acid ester of monosaccharides * Amino sugar * Deoxy sugars * Sugar acids * Sugar alcohols * Neuraminic acid * Sialic acid. * Glycosides * Furfural Derivative

Answer 111

These are formed from the reaction of phosphoric acid with hydroxyl group of the sugar, e.g. glucose-1-phosphate or glucose-6-phosphate.

Answer 112

* Phosphorylation of sugar within cells is essential to prevent the diffusion of the sugar out of the cell. * Nucleic acids (RNA and DNA) of cell nuclei also contain sugar phosphates of ribose and deoxyribose

Answer 113

Amino sugars have a hydroxyl group replaced by an amino or an acetylated amino (acetylamino) group. For example, glucosamine, N-acetyl glucosamine galactosamine and mannosamine.

Answer 114

* Amino sugars are components of glycolipid (ganglioside), glycoprotein and proteoglycans (glycosaminoglycans). * Several antibiotics, e.g. erythromycin, carbomycin contain amino sugar.

Answer 115

Deoxy sugars possess a hydrogen atom in place of one of their hydroxy groups e.g. 2-deoxyribose found in nucleic acid DNA.

Answer 116

Deoxyribose * Oxygen is removed from 2nd position * Is an important component of DNA * Feulgen staining is specific for 2 deoxy sugars (and DNA) in the tissues. L–Fucose * Deoxy Sugar present in the Blood group antigens. 2-Deoxy Glucose * Experimentally an inhibitor of Glucose metabolism

Answer 117

Formed by oxidation of aldehyde carbon atom, hydroxyl carbon atom or both of monosaccharides.

Answer 118

* Ascorbic acid or vitamin C (not synthesized by human beings) is required for the synthesis of collagen. It acts as water soluble antioxidant. * Glucuronic acid (uronic acid) is a component of GAGs

Answer 119

Monosaccharides are reduced at their carbonyl group to yield corresponding polyhydroxyalcohols * Aldoses undergo reduction to form corresponding Alcohol * Ketoses form two alcohols because of appearance of new asymmetric carbon atom.

Answer 120

* Mannitol is used to reduce intracranial pressure by forced diuresis * Osmotic effect of Dulcitol and Sorbitol causes cataract in Galactosemia and Diabetes respectively * Polyol pathway is responsible for the development of Diabetic cataract. * they are used as non-glucose forming sweetners in food stuffs for diabetics, sorbitol and xylitol are the most commonly used.

Answer 121

Neuraminic acid is a nine carbon sugar derived from mannosamine (an epimer of glucosamine) and pyruvate. Mannosamine + Pyruvate ————> Neuraminic acid.

Answer 122

Sialic acids are acetylated derivatives of neuraminic acid in which amino (NH2) or hydroxy (OH) group is acetylated.

Answer 123

Sialic acids are constituents of both glycoproteins and glycolipids (ganglioside).

Answer 124

Different compounds having same molecular formula are called isomers of one another.

Answer 125

Lebervon’t Hoff Rule: The relationship between the number of Asymmetric Carbon atom and the number of Stereoisomers possible. Number of isomers = 2 n {where n is the number of Asymmetric Carbon atom.}

Answer 126

The carbon atom to which four different substituent groups are attached is called a chiral or asymmetric carbon atom

Answer 127

* Stereoisomerism * Opticalisomerism.

Answer 128

Compounds having the same molecular formula but different spatial configuration of H and OH group around the asymmetric carbon atoms

Answer 129

It is the difference in the orientation of H and OH group around penultimate carbon atom results in two mirror images. The penultimate carbon atom is called Reference Carbon atom (in Glucose and Fructose is C-5)

Answer 130

• D Glucose and L Glucose • D Fructose and L Fructose • D Mannose and L Mannose • D Glyceraldehyde and L Glyceraldehyde.

Answer 131

• Formation of ring structure in monosaccharides results in creation of an additional asymmetric carbon called anomeric Carbon atom • The carbon atom with functional group forms the anomeric carbon atom • In Glucose C-1 and in fructose C-2 form the anomeric carbon atom • Difference in orientation of H and OH group around the anomeric carbon atom results in Anomerism • The resulting isomers are called α and β anomers.

Answer 132

• α D Glucose and β D Glucose • α D Fructose and β D Fructose.

Answer 133

• Mutarotation is change in optical rotation of plane polarized light with time • Mutarotation is a property of Anomeric Carbon atom • Mutarotation is studied by measuring the rotation of plane polarized light • The optical rotation of α D Glucose is + 112° • The optical rotation of β D Glucose is + 19° • Both undergo mutarotation over a period of a few hours, an equilibrium is attained • At equilibrium the optical rotation is + 52°.

Answer 134

When 2 monosaccharides differ from each other in their configuration around a single asymmetric carbon (other than anomeric carbon) atom, they are referred to as epimers of each other.

Answer 135

Glucose has epimers at C2, C3, C4 C2- Mannose C3- Allose C4- Galactose

Answer 136

• When a beam of plane polarized light is passed through a solution of carbohydrates, it rotates the light either to right or to left. Depends on the direction of rotation, 2 optical isomers possible • Dextrorotatory (represented by d or +) • Rotate plane polarized light to right (Clock-wise) • Levorotatory (represented by l or –) • Rotate plane polarized light to left (Anticlockwise) • D Glucose is dextrorotatory (i.e. why glucose is also called Dextrose) but D Fructose is levorotatory.

Answer 137

Equimolar mixture of optical isomers which has no net rotation of plane polarized light.

Answer 138

Sucrose is dextrorotatory. On hydrolysis of Sucrose yield a mixture of dextrorotatory Glucose and levorotatory Fructose. Because of strong levorotatory nature of fructose, Sucrose on hydrolysis is levorotatory. Hence, Sucrose is called invert sugar

Answer 139

dihydroxyacetone

Answer 140

Glucose, fructose, mannose

Answer 141

Osazones are yellow or orange crystalline derivatives of reducing sugars with phenylhydrazine and have a characteristic crystal structure, which can be used for identification and characterization of different sugars having closely similar properties (like maltose and lactose).

Answer 142

mouth stomach intestine

Answer 143

1. In the mouth, salivary a-amylase cleaves starch by breaking a-1,4 linkages between glucose residues within the chains. 2. Dextrins (linear and branched oligosaccharides) are the major products that enter the stomach.

Answer 144

Carbohydrate digestion halts temporarily in the stomach because the high acidity inactivates the salivary α-amylase.

Answer 145

1. The stomach contents pass into the intestine, where bicarbonate (HCO3) secreted by the pancreas neutralizes the stomach acid, raising the pH into the optimal range for the action of the intestinal enzymes. There are now 2 phases of intestinal digestion: -Digestion by pancreatic enzymes -Digestion by intestinal enzymes

Answer 146

-The pancreas secretes an a-amylase that acts in the lumen of the small intestine and, like salivary amylase, cleaves a-1,4 linkages between glucose residues. The products of pancreatic a-amylase are: - the disaccharides (maltose and isomaltase), -trisaccharides, and -small oligosaccharides containing a-1,4 and a-1,6 linkages.

Answer 147

Complexes of enzymes, produced by intestinal epithelial cells and located in their brush borders, continue the digestion of carbohydrates. -Maltase breaks maltose into Glucose and Glucose -Isomaltase breaks Isomaltose into Glucose and Glucose -Lactase breaks lactose into Glucose and Galactose -Sucrase breaks sucrose into glucose and fructose -Dextrinase breaks Alpha-limit Dextrin into glucose and maltose

Answer 148

Carbohydrates are absorbed as monosaccharides from the intestinal lumen. Two mechanisms are responsible for the absorption of monosaccharides: -Active transport -Passive transport

Answer 149

It is transport against a concentration gradient, i.e. from a low glucose concentration to a higher concentration. The transport of glucose and galactose across the brush border membrane of mucosal cells occurs by an active transport. A sodium dependent glucose transporter (SGLT-1) binds both glucose and Na+ at separate sites and transports them both through the plasma membrane of the intestinal cell

Answer 150

* Fructose and mannose are transported across the brush border by a Na+ independent facilitative diffusion process, requiring specific glucose transporter, GLUT-5. * Movement of sugar in facilitative diffusion is strictly from a higher concentration to a lower one until it reaches an equilibrium. * The same transport can also be used by glucose and galactose if the concentration gradient is favourable.

Answer 151

The sodium independent transporter, GLUT-2 that facilitates transport of sugars out of the mucosal cells, thereby entering the portal circulation and being transported to the liver

Answer 152

This is the most common disorder due to deficiency of enzyme lactase. * In this condition, lactose accumulates in the gut which undergoes bacterial fermentation in the large intestine with the production of H2 and CO2 gases and low molecular weight acids like acetic acid, propionic acid and butyric acid which are osmotically active. * Abdominal cramps and flatulence result from the accumulation of gases and the osmotically active products that draw water from the intestinal cells into the lumen resulting in diarrhoea and dehydration. * Treatment for this disorder is simply to remove lactose from the diet.