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113 Cards in this Set
- Front
- Back
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What is the general formula of carbohydrates?
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(CH2O)n, n >= 3
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What are the two groups of carbohydrates?
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1- Polyhydroxyketones.
2- Polyhydroxyaldehydes. |
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The sugar unit is sometimes referred to as
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glycon
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Oligosaccharides are linked together by ... bonds
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glycosidic.
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Polysaccharides are also known as
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glycans
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What is the difference between a homopolysaccharide and a heteropolysaccharide?
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The former is a polymer of one type of monossacharides, the latter contains two or more types.
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Monosaccharides having an aldehyde group are called
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aldoses
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Monosaccharides having a ketone grp.
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ketoses
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Glyceryaldehyde is an
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aldotriose
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Dihydroxyacetone is a
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ketotriose
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What's the optical activity of glucose?
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Dextrorotary(dextrose)
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What's the optical activity of fructose?
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levorotatory
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What's the relationbship between the number of the assymetric carbon atom and the stereoisomers?
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n=number of assymetric atom
stereoisomers = 2^n |
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another name for stereoisomers
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enentiomers
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What is the number of assymetric carbon atoms in alsohexoses and the # of their stereoisomers?
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4
2^4 = 16 |
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Most carbohydrates in the body are
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D-form
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Name some natural L-form sugars
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L-arabinose, L-fucose(glycoproteins)
L-xylulose(intermediate in metabolism) |
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Give an example of an aldotetrose
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erythrose
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Give an example of a ketotetrose
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erythrulose
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What is the function of erthrose and erythrulose?
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They are intermediates in metabolic pathways
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From what can the pentoses be manufactured in the body?
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Glucose
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Pentoses are often found in which component of the diet
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Fruits
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Give an example of an aldopentose
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Ribose
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Give two examples of ketopentoses
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Ribulose and Xylulose
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Which carbon in D-Ribulose and D-Xylulose is an epimeric one?
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#3
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Name two pentose epimers
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D-Ribulose and D-Xylulose
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What is the biological importance of pentoses?
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1- They are constitutents of nucleotides(DNA, RNA, ATP, NAD, FAD)
2- Formation of secondary messengers(cAMP, cGMP). 3- They are components of some vitamins(ribitol in B2). |
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Give three examples of aldohexoses
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1- Glucose.
2- Mannose. 3- Galactose. |
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Give an exmaple of ketohexoses
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1- Fructose.
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What are the different aldohexose epimers?
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1- D-Glucose & D-Mannose(#2).
2- D-Glucose & D-Galactose(#4). |
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Give an example of an aldo-keto isomerism
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D-glucose and D-fructose
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the cyclic form of monohydroxyaldehydes forms
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Hemiacetal
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The cyclic form of monohydroxyketones forms
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Hemiketal
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What are the two ring structures formed by monosaccharides
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1- A puran ring(5 carbons, hexagon).
2- A furan ring(4 carbons, pentagon) |
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Aldohexoses are mainly present in which ring form?
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Pyran(pyranose)
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What form does fructose assume when it is phosphorylated or connected to other sugars?
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Furanose
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The exception to the Haworth configuration of cyclic sugars is:
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carbon #5
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The anomers are:
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Stereoisomers which are the result of the arise of the new assymetric carbon in the cyclic form.
The alpha anomer has the oh to the right while the beta anomer has the oh to the left. |
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L-Fucose is
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6 deoxy l-galactose
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What are the physiologically important sugar acids?
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1- Aldonic acid(oxidation of carbon #1 of D-Glucose).
2- Uronic acid.(oxidation of C#6 of D-glucose) |
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What are saccharic acids?
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They are sugar acids which are formed when a sugar is exposed to a strong oxidizing agent which oxidized both carbon #1 and carbon #6 producing gluccaric acid.
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What is the importance of glucoronic acid.
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1- A component of glycosaminoglycans.
2- Ity is involved in the metabolism of bilirubin. |
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What is the importance of iduronic acid?
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It is a component of glycosaminoglycans.
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Discuss: Vitamin C is a sugar acid
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L-Ascorbic acid.
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Oxidation of monosaccharides produces ....... while reduction of monosaccharides produces .....
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1- Sugar acids.(cooh)
2- Sugal alcohols.(oh) |
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Reduction of glucose gives
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sorbitol
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Reduction of mannose gives
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mannitol
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reduction of fructose gives
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sorbitol or mannitol
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reduction of galactose gives
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dulcitol(galactitol)
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reduction of ribose gives
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ribitol(b2)
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Inositol is a ...
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sugar alcohol
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Inositol can be found in
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muscles
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A sugar alcohol that can be considered a vitamin
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inositol(myo-inositol(b8))
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Phosphatidyl inositol can be found in
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cell membranes
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phytic acid is
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hexophosphoinositol
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what is the importance of phytic acid
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it forms a complex with dietary iron and calcium preventing their absorption.
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sugar phosphates can be found as
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intermediates in carbohydrate metabolism
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How are sugar phosphates kept in the cytosol
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they carry a negative charge which prevents them from leaving the cell
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How are glycosides formed?
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The hydroxyl group of an anomeric carbon atom is linked to a hedroxy group of another molecule with the elimination of water
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Disaccharides are joined by an
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O-glycosidic bond
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When does a disaccharide shows reducing characters, an optical activity, alpha & beta isomerism, and mutarotation?
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When the second sugar molecule binds to the first one uses a carbon different than its anomeric one
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What is the solution that hydrolyzes the glycosidic bond?
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an Acid
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What form of glycosidic bonds is found in nucleotides?
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N-glycosidic bond, the anomeric carbon is linked to an amino group
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Amylase + Starch =?
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Maltose
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What are the hydrolitic products of a maltose molecule?
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2 glucose molecules
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What is the bond binding the glycons of the maltose sugar?
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alpha 1->4 glycosidic bond
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What are the hydrolytic products of lactose?
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beta glucose and beta galactose
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What is the lactose concentration in human milk?
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7 gm % (alpha configuration)
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what is the lactose concentration in bovine milk?
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4 gm % (beta configuration)
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What are the hyrolytic products of sucrose?
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alpha glucose and beta fructose
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What is special about the disaccharide sucrose?
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It is a non reducing sugar since it doesn't have any free anomeric carbon atoms
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Why is sucrose called an invert sugar?
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Because it's dextrorotary in its bonded form but levorotary after hydrolysis.
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What is the importance of lactulose?
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It results in diarrhea which helps in eliminating the toxins
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What are the hydrolytic products of lactulose?
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Galactose and Fructose
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name two homopolysaccharides:
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Starch and glycogen.
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name two heteropolysaccharides
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Cellulose and chitin.
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what are the two forms of homopolysaccharides?
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Pentosans and Hexosans
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Name a galactosan
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Agar Agar
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Name a fructosan
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Inulin
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Name 5 glucosans
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1- Starch.
2- Dextrins. 3- Glycogen. 4- Dextran. 5- Cellulose. |
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Give another name for heteroglycans
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Glycosaminoglycans
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What is the importance of glycosaminoglycans?
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1- They provide the intercellular matrix.
2- They povide toughness and flexibility for cartilage and bones. 3- Viscosity and lubricating properties for extracellular secretions. 4- They are important for cell typing. |
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Starch is a mixture of
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Amylose and Amylopectin
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Amylose + iodine = ?
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blue
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Amylopectin + Iodine =
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red
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Amylodextrins + iodine
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Violet
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Erythrodextrins + iodine
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red
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Achrodextrins + iodine
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No color
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What type of carbohydrates is used for adhesion purposes?
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Dextrins
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What are the similarities and differences between glycogen and amylopectin?
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Similarities:
1- Bonds (alpha 1-> 4 glucosidic main chain and alpha 1->6 at the branching points) Differences: 1- It has more branches, the branching occurs every 8-12 residues. |
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Glycogen + iodine?
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Pink
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Whgat is the difference between dextrans, glycogen, and starch?
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Dextrans are exclusively linked by alpha 1->6 bonds in the main chain and either alpha 1->2, 3, or 4 at the branching points.
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What is the function of Dextrans?
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1- They are used as plasma substitutents in cases of hemorrhages.
2- Dextran-iron complex is used in the treatment of anemia. 3- Dextran-sulfate is used as an anti-coagulant. |
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What is the bonding nature of cellulose?
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Beta 1->4 glycosidic bonds.
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What's the special characteristic of cellulose's chain?
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It is a straight chain.
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What is the function of agar agar?
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It is used as a bacterial culture medium.
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What is the function of inulin?
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It is used as a marker for glomerular filtration.
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All glycosaminoglycans are sulfated except for:
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Hyaluronate
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Name six glycosaminoglycans:
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1- Hyaluronic acid.
2- Chondroitin sulfate. 3- Dermatan sulfate. 4- Heparin. 5- Heparan sulfate. 6- Keratan sulfate. |
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What are the hydrolytic products of hyaluronic acid?
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N-acetyl glucosamine and glucoronic acid.
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Where can hyaluronic acid be found?
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1- Vitreous of the eye.
2- Synovial fluid. 3- Umbilical cord. |
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What are the hydrolytic products of chondroitin sulfate?
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N-acetyl galactosamine and glucuronic acid.
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Where can the sulfate group be found in chondroitin sulfate?
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at position #4 or position #6
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Where can chondroitin sulfate be found?
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Cartilages, tendons, ligaments, and the aorta
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What are the hydrolytic products of heparin.
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1- Glucosamine(minimally acetylated highly sulfated)
2- D-glucuronic acid with variable amounts ofiduronic acid. |
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what is the carbon 5 epimer of glucuronic acid?
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Iduronic acid
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What are the functions of heparin?
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1- Anti-coagulant.
2- Lipid clearing agent. |
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What is the difference between heparin and heparan sulfate?
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Heparan sulfate has more acetyl groups and fewer sulfate groups.
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What are the hydrolytic products of dermatan sulfate?
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N/acety galactosamine, L-iduronic acid, and variable amounts of D-glucuronic acid.
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What is the glycosaminoglycan that doesn't contain a uronic acid?
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Keratan sulfate
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What are the hydrolytic products of keratan sulfate?
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N-acetyl glucosamine and galactose
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What are the two types of keratan sulfate and where can they be found?
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1- Keratan sulfate I: cornea.
2- Keratan sulfate II : cartilage. |
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How may the carbohydrates be bound to the protein units in glycoproteins?
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Through an O link(Serine or threonine)
Or through an N link(Asparagine) |
