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OAU BCH > Carbohydrate > Flashcards

Carbohydrate Flashcards

1
Q

What are carbohydrates?

A

Polyhydroxyl aldehyde and ketones or compounds which yield any of these compounds upon hydrolysis.

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2
Q

What is the reserved carbohydrate in bulb of onion and garlic?

A

Inulin

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3
Q

What is the fate of excess carbohydrate?

A

Converted to fat (triglycerides) and stored for later use.

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4
Q

Immunological specificity is also a function of carbohydrate, true/false?

A

True (blood group polysaccharides)

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5
Q

What are monosaccharides?

A

They are the simplest form of carbohydrate, they contain a single unit of sugar and can not be hydrolysed into smaller units.

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6
Q

Examples of monosaccharides

A

Glyceraldehyde

Glucose

Galactose

Fructose

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7
Q

What are disaccharides?

A

Disaccharides are carbohydrates with two monosaccharides, they are formed by the combination of two monosaccharides with the elimination of water.

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8
Q

Homopolysaccharides?

A

These are polysaccharides made up of the same monosaccharide units.

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9
Q

Oligosaccharides

A

Carbonhydrates with 5-10 sugar molecules.

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10
Q

Polysaccharides

A

Carbohydrates with 11 or more monosaccharides.

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11
Q

Heteropolysaccharide

A

Polysaccharides made up of different monosaccharides.

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12
Q

Examples of disaccharides

A

Maltose

Sucrose

Lactose

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13
Q

Glucose + Galactose = ?

A

Lactose

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14
Q

Glucose + Glucose =?

A

Maltose

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15
Q

Types of isomers sugars can undergo?

A

Structural isomer

Stereoisomer

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16
Q

Structural isomer?

A

Compounds that have the same molecular formula but different structural formula

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17
Q

Examples of structural isomers of sugars

A

Aldose-ketose isomerism:

Glucose and fructose

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18
Q

Stereoisomers?

A

Compounds with same molecular and structural formula but differ in spatial configuration of their atoms.

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19
Q

Asymmetric carbon?

A

Carbon atoms attached to two carbon atoms and two other non-carbon atoms. Also called chiral centers.

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20
Q

What monosaccharide is not optically active and why?

A

Dihydroxyacetone because it has no chiral center.

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21
Q

D-Galactose is a structural isomer of D-Glucose

True/False

A

False.

D-Galactose is an epimer of D-Glucose.

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22
Q

How is D-manose different from D-Glucose?

A

D-manose differs to D-Glucose only with respect to carbon 2.

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23
Q

What are epimers?

A

Epimers are sugars that differ from eachother in spatial configuration only with respect to one carbon atom other than the reference carbon atom (carbon 5 in glucose).

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24
Q

Diastereoisomers

A

These are non-identical and non-mirror image stereoisomers. This occurs when stereoisomers of a compound have different configurations at one or more (but not all) stereocenters. É.g epimers, anomerism.

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25
Q

What is anomerism?

A

This is the phenomenon where the configuration of stereoisomers differ only at the anomeric carbon.
E.g alpha-D-glucose & beta-D-glucose

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26
Q

Anomeric carbon?

A

This is the carbon with the functional group attached to it.

27
Q

Explain D & L isomerism

A

In this isomerism, the spatial configuration of all H and OH present in the sugar are reversed thereby forming a mirror image of the sugar

28
Q

L-Glucose can be digested by man

True/False

A

False. Only D-Glucose can be digested by man

29
Q

What is Mutarotation

A

Mutarotation is the change in specific optical rotation by interconversions of alpha & beta D-Glucose to an equilibrium mixture of the two forms.

30
Q

In a mixture of glucose after 18 hours what is the percentage of alpha and beta D-Glucose present?

A

63% beta D-glucopyranose

36 alpha D-glucopyranose

1% glucofuranose

31
Q

What happens when monosaccharides are treated with conc sulphuric acid?

A

Dehydration and removal of 3 molecules of water. Hexoses give hydroxymethyl furfural and pentoses give furfural.

32
Q

What chemical reactions of carbonhydrates forms the basis of Molisch test?

A

Dehydration of mono saccharides with sulphuric acid.

33
Q

What’s an enediol?

A

Enediol is the enol form of sugar because two hydroxyl groups are attached to the double-bonded carbon.

34
Q

How are enediol formed?

A

Monosaccharides are treated with dilute alkali solution which converts both aldose and ketose into enediol.

35
Q

Importance of D-Glucose

A

Blood sugar

Main source of energy in the body

36
Q

Importance of D-fructose

A

Constituent of sucrose

Common sugar

Constituent of honey

37
Q

Importance of D-Galactose

A

Constituent of glycoproteins

Constituent of glycolipids

Constituent of lactose

38
Q

Importance of D-manose

A

Constituent of glycoproteins

Constituent of globulins

Constituent of mucoprotein

39
Q

What is dextrorotatory

A

This is a condition where a beam of plane polarised light that passes through a solution of glucose gets rotated to the right.

40
Q

What is used to detect the presence of glucose in urine?

A

Benedict’s reagent

41
Q

What is glucosuria

A

This is the condition where glucose is found in the urine (as a result of diabetes mellitus).

42
Q

Non-reducing sugars can form ozazones?

T/F

A

F.

Only non-reducing sugars can form ozazones by heating with excess phenylhydrazine

43
Q

What ozazone crystals does mannose form?

A

Needle-shaped crystals. Same with glucose & fructose

44
Q

What shape of ozazone crystals does lactose form?

A

Hedgehog or pincushion with pin shape

45
Q

What shape of ozazone crystals does maltose form?

A

Sunflower or petal-shaped crystals.

46
Q

The closed chain structure of glucose is called?

A

Fischer projection

47
Q

Clinical correlates of ozazone?

A

May be used to differentiate sugars in biological fluid like urine or blood

48
Q

What serves as the general carbonhydrates test?

A

Molisch test

49
Q

Clinical importance of mucic acid?

A

Forms in soluble crystals, forms a basis for test for galactose

50
Q

How is mucic acid formed?

A

Mucic acid is formed by the oxidation of the first and terminal primary alcohol group of galactose to form dicarboxylic acid under nitric acid and heat.

51
Q

Examples of saccharic acids?

A

Glucosaccharic acid

Mannaric acid

Mucic acid

52
Q

Clinical importance of calcium gluconate?

A

Solution is given intravenously to raise calcium levels in blood

53
Q

How are aldonic acids formed

A

Oxidation of aldose sugars in the presence of hypobromous acid leads to oxidation of the aldehyde group into carboxy group to produce aldonic acids

54
Q

Another name for saccharic acids?

A

Alderic acid

55
Q

Hownis uronic acid made?

A

When the aldehyde group is protected, the terminal primary alcohol is oxidized to carboxylic acid forming uronic acid

56
Q

Clinical importance of uronic acids

A

Glucuronic acid is used by the body during detoxification of drugs and other xenobiotics.

It is also used for the synthesis of other heteropolysaccharides.

57
Q

Hexoses give what molecule after dehydration using sulphuric acid

A

Hydroxymethyl furfural + 3 molecules of water

58
Q

What are the reactions monosaccharides undergo?

A

Dehydration using conc sulphuric acid

Oxidation

Reduction using H in the presence of sodium amalgam

59
Q

How is D-sorbitol formed?

A

D-Glucose is reduced with H in the presence of sodium amalgam to form a corresponding alcohol called D-sorbitol

60
Q

Why can fructose be reduced to two sugar alcohols

A

Because it is a ketose and ketose forms to alcohols due to the appearance of a new asymmetric carbon atom.

61
Q

Galactose is reduced to what?

A

Dulcitol

62
Q

What sugar alcohol is used to identify bacterial colonies?

A

Sorbitol, mannitol & dulcitol

63
Q

What leads to diabetic cataract in the eyes of a human?

A

Increased concentration of dulcitol and sorbitol in the lens of eyes

OAU BCH (7 decks)

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