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BCHEM FINALS ! > LAB Exp 5. Carbs > Flashcards

LAB Exp 5. Carbs Flashcards

1
Q

Energy storage for polysaccharide implants

A

Starch

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2
Q

Energy reserve for animals

A

Glycogen

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3
Q

Glycogen provides sugar for ___ to ___ hours when fasting

A

24-36

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4
Q

Carbohydrate with the same kind of monosaccharides

A

Homoglycan

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5
Q

Source of starch

A

Cassava and potato

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6
Q

Source of glycogen

A

Chicken liver

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7
Q

Principle of starch isolation

A

Selective dissolution (starch is slightly soluble in H2O)

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8
Q

Principle of glycogen isolation

A

Homogenization

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9
Q

Process that ruptures the membranes

A

Homogenization

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10
Q

2 physical methods of homogenization

A

Chemical
Enzymatic

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11
Q

Role of 10% TCA in homogenization

A

Removes protein by precipitation

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12
Q

Role of 95% EtOH in homogenization

A

Precipitates glycogen from the homogenized sample

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13
Q

The loss of H2O shell surrounding glycogen molecule

A

Precipitation

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14
Q

Reagent that facilitates precipitation of glycogen by salting-out

A

NaCl

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15
Q

Starch is composed of two polysaccharides, namely

A

Amylose
Amylopectin

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16
Q

The linear homoglycan of glucose connected by alpha 1-4 linkages

A

Amylose

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17
Q

Which polysaccharide has linkages that are flexible, which allows chain to coil?

A

Amylose

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18
Q

Gives the purple color of starch

A

I2 trapped in coil

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19
Q

The branched homoglycan with approx. 1 in 25 glucose linked in both alpha 1-4 and alpha 1-6

A

Amylopectin

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20
Q

Connected by alpha 1-4 glycosidic bonds

A

Linear chains

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21
Q

alpha 1-6

A

Branched points

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22
Q

Highly branched are considered in every __ in 10 glucose units

A

1

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23
Q

Purpose of molisch’s test

A

Detects presence of carbohydrates

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24
Q

Reagents for molisch’s test

A

H2SO4, EtOH, and alpha-naphthol

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25
Q

Positive result for molisch’s test

A

Purple ring at interphase

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26
Q

Principle of molisch’s test

A

Strong acid (H2SO4) to dehydrate monosaccharide to produce furfural or hydroxymethylfurfural

Intermediate furfural derivatives will condense with a-naphthol

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27
Q

Purpose of Iodine test

A

Detect the presence of polysaccharides

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28
Q

Reagents for iodine test

A

KI

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29
Q

Positive result for iodine test

A

Blue-black solution (starch-iodo complexation)

Red or pink solution (glycogen-iodo complex)

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30
Q

Principle of iodine test

A

Iodine slides into starch coil to give blue-black color

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31
Q

Purpose of benedict’s test

A

Detect reducing sugars

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32
Q

Reagent for benedict’s test

A

CuSO4, Na2CO3, Na3C6H5O7

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33
Q

Positive result for benedict’s test

A

Brick-red ppt for all reducing saccharides (all monosaccharides)

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34
Q

Principle of benedict’s test

A

Cu2+ oxidizing agent (oxidation)

Cupric ions are reduced to cuprous to form Cu2O ppt

Sodium citrate (basic) is used to keep Cu ions in the solution

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35
Q

Purpose of barfoed’s test

A

Distinguishes reducing monosaccharides and disaccharides

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36
Q

Reagents for barfoed’s test

A

Cu(CH3COO2), acetic acid

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37
Q

Positive result for barfoed’s test

A

Brick-red ppt for all reducing monosaccharides

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38
Q

Principle of barfoed’s test

A

Cu2+ oxidizing agent (oxidation)

Cupric ions are reduced to cuprous to form Cu2O ppt

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39
Q

Purpose of seliwanoff’s test

A

Distinguish aldoses from ketoses (ketohexoses)

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40
Q

Reagent for seliwanoff’s test

A

HCl, resorcinol

41
Q

Positive result for seliwanoff’s test

A

Cherry-red solution for ketohexoses

42
Q

Principle of seliwanoff’s test

A

Strong acid dehydrates the monosaccharide to produce furfural/hydromethylfurfural, then condensation with resorcinol

43
Q

Purpose of bial’s orcinol test

A

Specific for pentoses

44
Q

Reagents for bial’s orcinol test

A

HCl, FeCl3, orcinol

45
Q

Positive result for bial’s orcinol test

A

Blue-green solution for aldopentoses

46
Q

Principle of bial’s orcinol test

A

Strong acid dehydrates the monosaccharide to produce furfural/hydromethylfurfural, then condensation with orcinol

47
Q

Purpose of mucic acid test

A

Specific for galactose and lactose

48
Q

Reagent for mucic acid test

A

Conc HNO3

49
Q

Positive result for mucic acid test

A

Broken glass-like or rhombic crystals

50
Q

Principle of mucic acid test

A

HNO3 - strong oxidizing agent

Formyl will get oxidized into carboxylic acid

Primary alcohol will get oxidized to carboxylic acid

51
Q

Purpose of osazone/phenylhydrazone test (all aldoses and ketoses)

A

For all sugars with free carbonyl group at C1/C2

52
Q

Reagent for osazone/phenylhydrazone test

A

Phenylhydrazone

53
Q

Positive result for osazone/phenylhydrazone test

A

Yellow-orange crystals (osazones)

D-glucosazone (for glucose)

No “sucrosazone”

54
Q

Principle of osazone/phenylhydrazone test

A

Phenylhydrazine - strong oxidizing agent

Formyl functional group will get oxidized to carboxylic acid

Secondary alcohol will get oxidized to ketone

Product: phenylhydrazone + phenylhydrazine = osazone

55
Q

Time of appearance of mannose from phenylhydrazone test

A

0.5 mins

56
Q

Time of appearance of fructose from phenylhydrazone test

A

2 mins

57
Q

Time of appearance of glucose from phenylhydrazone test

A

4-5 mins

58
Q

Time of appearance of xylose from phenylhydrazone test

A

7 mins

59
Q

Time of appearance of galactose from phenylhydrazone test

A

15-19 mins

60
Q

Time of appearance of maltose from phenylhydrazone test

A

soluble in hot water

61
Q

Time of appearance of lactose from phenylhydrazone test

A

soluble in hot water

62
Q

Characteristics of mannose crystal in phenylhydrazone test

A

Needle-like/feathery

63
Q

Characteristics of fructose crystal in phenylhydrazone test

A

Needle-like/feathery;
Broomstick

64
Q

Characteristics of glucose crystal in phenylhydrazone test

A

Needle-like/feathery;
Broomstick

65
Q

Characteristics of xylose crystal in phenylhydrazone test

A

Long, fine needle-like crystals

65
Q

Characteristics of galactose crystal in phenylhydrazone test

A

Broad/flat crystals

66
Q

Characteristics of maltose crystal in phenylhydrazone test

A

Broad, needle-like crystals;
Sunflower-shaped

67
Q

Characteristics of lactose crystal in phenylhydrazone test

A

Fine needles, grouped in balls;
Hedgehog-shaped

68
Q

A quantitative analysis that measures the amount of carbohydrates present in a given sample

A

Nelson’s method

69
Q

Nelson’s method is based on capacity of the _____

A

Free reducing group of sugars to reduce Cu2+ in an alkaline solution

70
Q

Principle of nelson’s method

A

Sample is colorless; adding reagents oxidizes reducing sugars into aldonic acids

71
Q

Reagents for Nelson’s A

A

Rochelle salt
Sodium potassium tartrate
Na2CO3, NaHCO3, Na2, SO4

72
Q

Purpose of CuSO4 in Nelson’s method

A

Oxidizing agent

73
Q

Purpose of Na2CO3 and NaHCO3 in Nelson’s method

A

makes sugar more reactive

74
Q

Purpose of NaKtartrate in Nelson’s method

A

Prevents ppt of Cu(OH)2

75
Q

T/F: Nelson’s A & B are mixed before using NaKtartrate

A

F

76
Q

Reagents for Nelson’s B

A

CuSO4 x 5H2O
H2SO4

77
Q

Reagents for Ammonium molybdate reagent

A

(NH4)2MoO4
H2SO4
Na2HASO4 x 7H2O

78
Q

Purpose of ammonium molybdate reagent

A

Added to dissolve Cu2O

79
Q

Principle of ammonium molybdate reagent

A

Converted into molybdenum blue; the intensity of blue coloration is dependent to the amount of Cu2O formed

80
Q

A homoglycan is a mixture of 2 polysaccharides, namely _____ and _____

A

Amylose and amylopectin

81
Q

Erythrose is an example of _____ (in terms of number of carbons)

A

Tetrose

82
Q

Glyceraldehyde is an example of _____ (in terms of number of carbons)

A

Triose

83
Q

Ribose is an example of _____ (in terms of number of carbons)

A

Pentose

84
Q

Glucose and fructose are examples of _____ (in terms of number of carbons)

A

Hexose

85
Q

Sedoheptulose is an example of _____ (in terms of number of carbons)

A

Heptose

86
Q

Neuramic acid is an example of _____ (in terms of number of carbons)

A

Nonose

87
Q

Hydrolyzable polymers of 2-6 monosaccharides

A

Oligosaccharides

88
Q
A
89
Q

Sucrose and lactose are examples of _____

A

Disaccharides

90
Q

Hydrolyzable polymers of >6 monosaccharides

A

Polysaccharides

91
Q

Polymer of a single type of monosaccharide

A

Homopolysaccharides

92
Q

Glycogen and cellulose are examples of _____

A

Homopolysaccharides

93
Q

Polymer of at least 2 types of monosaccharide

A

Heteropolysaccharides

94
Q

Glucosaminoglycan is an example of _____

A

Heteropolysaccharide

95
Q

Fumaric acid and maleic acid are examples of _____ (type of isomer)

A

Cis-trans isomers

96
Q

2-Phosphoglycerate and 3-Phosphoglycerate are examples of _____ (type of isomers)

A

Positional isomers

97
Q
A

BCHEM FINALS ! (7 decks)

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