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BIO 024: Biochemistry > Laboratory: Carbohydrates > Flashcards

Laboratory: Carbohydrates Flashcards

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1
Q

General Tests for Carbohydrates:

The reaction is based on the fact that concentrated H2SO4 (dehydrating agent) catalyses the dehydration of sugars to form furfural (from pentoses) or hydroxymethyl furfural (from hexoses).

A

Molisch Test

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2
Q

T.R. of Molisch Test

A

purple or violet coloured ring at the junction

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3
Q

General Tests for Carbohydrates:
Its principle is same as that for molisch’s test except that the furfurals and hydroxy -methyl furfurals give condensation products with anthrone that are bluish green in colour.

A

Anthrone’s Test

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4
Q

T.R. of Anthrone’s Test

A

Bluish-green color

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5
Q

General Tests for Carbohydrates:
is used to test for the presence of starch.

A

Iodine Test

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6
Q

Iodine Test: Starch turns into an intense “_______” colour upon addition of aqueous solutions of the triiodide anion, due to the formation of an intermolecular charge-transfer complex.

A

“blue-black”

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7
Q

Iodine Test: In the absence of starch, the ______ colour of the aqueous solution remains.

A

brown

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8
Q

Specific tests for carbohydrates:

This test is a timed colour reaction specific for ketohexoses.

A

SELIWANOFF’S TESTS

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9
Q

Seliwanoff’s Test is named after ______.

A

Theodor Seliwanoff

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10
Q

T.R. for Seliwanoff’s Test

A

red coloured complex

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11
Q

Specific tests for carbohydrates:

This test is specific for pentoses and the compounds containing pentoses and thus useful for the determination of pentose sugars

A

BIAL’S ORCINOL

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12
Q

T.R. for Bial’s Orcinol

A

blue green coloured complex

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13
Q

Specific tests for carbohydrates:

This test is highly specific for galactose which is either independently present in solutions or obtained by the hydrolysis of lactose

A

MUCIC ACID TEST

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14
Q

Specific tests for carbohydrates:

a.k.a PHENYLHYDRAZINE TEST OR KOWARSKY TEST

A

OSAZONE TEST

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15
Q

Specific tests for carbohydrates:

An organic compound phenylhydrazine reacts with carbonyl carbon (or more specifically C1 and C2) of sugar to form the compound called osazones or phenylhydrazone.

A

OSAZONE TEST

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16
Q

Specific tests for carbohydrates:

A test to detect reducing and non-reducing sugar

A

FEHLING’S TEST

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17
Q

Specific tests for carbohydrates:

This test can be used to screen for glucose in urine, thus detecting diabetes.

A

FEHLING’S TEST

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18
Q

T.R. for Fehling’s Test

A

brick-red precipitate of Cu2O.

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19
Q

Specific tests for carbohydrates:

This test is performed to distinguish between a reducing mono- and disaccharide.

A

BARFOED’S TEST

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20
Q

Specific tests for carbohydrates:

modified the Fehling’s solution to produce an improved single reagent which quite stable.

A

BENEDICT’S TEST

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21
Q

Benedict’s Test: Blue colored solution

A

No significant change

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22
Q

Benedict’s Test: Green/Yellow precipitation

A

Traces of reducing sugar

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23
Q

Benedict’s Test: Orange color

A

Moderate

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24
Q

Benedict’s Test: Brick-red precipitation

A

Large amount of reducing sugar

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25
Q

Other tests for carbohydrates:

Test for galactose is also based on the formation of similar intermediate furfurals which condenses with phloroglucinol to form a red colored compound.

A

Tollen’s phloroglucinol test

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26
Q

Other tests for carbohydrates:

The production of violet color indicates the presence of pentose.

A

Tauber’s benzidine Test

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27
Q

Other tests for carbohydrates:

for polysaccharides; This test is performed to distinguish polysaccharides from mono- and disaccharides

A

Iodine test

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28
Q

It is the Principal storage form of carbohydrates in the mammalian body

A

Glycogen

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29
Q

A decrease in the glucose level below _________ causes brain dysfunction which can lead to coma and death.

A

70 mg/dL (hypoglycemia)

30
Q

It is not generally available to other tissues because muscles lack the enzyme glucose-6-phosphatase

A

Muscle glycogen

31
Q

It provides a source of energy for muscle contraction and is a readily available source of glucose for glycolysis within the muscle itself.

A

Muscle glycogen

32
Q

Glycogen is synthesized from glucose by the pathway of ________, which occurs mainly in liver and muscle.

A

glycogenesis

33
Q

catalyzes formation of glycosidic bonds between C1 of the activated glucose of UDPGlc and C4 of a terminal glucose residue at the non-reducing end of glycogen, liberating uridine diphosphate (UDP)

A

Glycogen synthase

34
Q

can only extend existing chain of glycogen.

A

Glycogen synthase

35
Q

a.k.a. glycogen primer

A

Glycogenin

36
Q

must be present to initiate glycogen biosynthesis

A

Glycogenin

37
Q

This integrates the regulation of glycogenolysis and glycogenesis by promoting the simultaneous activation of phosphorylase and inhibition of glycogen synthase.

A

Cyclic adenosine-3’,5’- monophosphate
(cAMP)

38
Q

______ acts reciprocally by inhibiting glycogenolysis and stimulating glycogenesis.

A

Insulin

39
Q

Test for Keto Sugar

A

SELIWANOFF’S TESTS

40
Q

What is the chelating agent for Benedict’s Test?

A

Sodium Citrate

41
Q

Based on oxidation:

What is the T.R. of Glucose on Fehling’s Test?

A

Brick red ppt

42
Q

Based on oxidation:

What is the T.R. of Fructose on Fehling’s Test?

A

Brick red
ppt

43
Q

Based on oxidation:

What is the T.R. of Galactose on Fehling’s Test?

A

Brick red
ppt

44
Q

Based on oxidation:

What is the T.R. of Maltose on Fehling’s Test?

A

Brick red
ppt

45
Q

Based on oxidation:

What is the T.R. of Sucrose on Fehling’s Test?

A

Blue

46
Q

Based on oxidation:

What is the T.R. of Lactose on Fehling’s Test?

A

Brick red
ppt

47
Q

Based on oxidation:

What is the T.R. of Lactose on Benedict’s Test?

A

Brick red
ppt

48
Q

Based on oxidation:

What is the T.R. of Sucrose on Benedict’s Test?

A

Blue

49
Q

Based on oxidation:

What is the T.R. of Maltose on Benedict’s Test?

A

Brick red
ppt

50
Q

Based on oxidation:

What is the T.R. of Galactose on Benedict’s Test?

A

Brick red
ppt

51
Q

Based on oxidation:

What is the T.R. of Fructose on Benedict’s Test?

A

Brick red
ppt

52
Q

Based on oxidation:

What is the T.R. of Glucose on Benedict’s Test?

A

Brick red
ppt

53
Q

Based on oxidation:

What is the T.R. of Glucose on Barfoed’s Test?

A

Brick red ppt

54
Q

Based on oxidation:

What is the T.R. of Fructose on Barfoed’s Test?

A

Brick red ppt

55
Q

Based on oxidation:

What is the T.R. of Galactose on Barfoed’s Test?

A

Brick red ppt

56
Q

Based on oxidation:

What is the T.R. of Maltose on Barfoed’s Test?

A

Brick red ppt

57
Q

Based on oxidation:

What is the T.R. of Sucrose on Barfoed’s Test?

A

Blue

58
Q

Based on oxidation:

What is the T.R. of Lactose on Barfoed’s Test?

A

Brick red ppt

59
Q

On which reducing sugars shows Needle-like crystals T.R. for Mucic Acid Test?

A

Galactose and Lactose

60
Q

General test for carbohydrates:

What is the T.R. of Glycogen on Molish Test?

A

Violet ring at the junction

61
Q

General test for carbohydrates:

What is the T.R. of Starch on Molish Test?

A

Violet ring
at the
junction

62
Q

General test for carbohydrates:

What is the T.R. of Starch on Anthrone’s Test?

A

Bluish green

63
Q

General test for carbohydrates:

What is the T.R. of Glycogen on Anthrone’s Test?

A

Bluish green

64
Q

General test for carbohydrates:

What is the T.R. of Glycogen on the Iodine Test?

A

Yellow-brown (maltose)

65
Q

General test for carbohydrates:

What is the T.R. of Starch on the Iodine Test?

A

Blue-violet

66
Q

BASED ON THE FURFURAL FORMATION AND ITS DERIVATIVES:

What is the T.R. of Glucose on Seliwanoff’s Test?

A

Yellow initially, red w/ prolonged heating for 15 mins

67
Q

BASED ON THE FURFURAL FORMATION AND ITS DERIVATIVES:

What is the T.R. of Xylose on Seliwanoff’s Test?

A

Yellow initially, red w/ prolonged heating for 15 mins

68
Q

BASED ON THE FURFURAL FORMATION AND ITS DERIVATIVES:

What is the T.R. of Fructose on Seliwanoff’s Test?

A

Cherry red or red (immediately
dehydrated)

69
Q

BASED ON THE FURFURAL FORMATION AND ITS DERIVATIVES:

What is the T.R. of Fructose on Bial’s Test?

A

Brown/dark red (-)

70
Q

BASED ON THE FURFURAL FORMATION AND ITS DERIVATIVES:

What is the T.R. of Xylose on Bial’s Test?

A

Blue green (+)

71
Q

nBASED ON THE FURFURAL FORMATION AND ITS DERIVATIVES:

What is the T.R. of Glucose on Bial’s Test?

A

Brown/dark red (-)

BIO 024: Biochemistry (16 decks)

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