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Biochem Lab > Experiment #14: COLOR REACTION OF PROTEINS > Flashcards

Experiment #14: COLOR REACTION OF PROTEINS Flashcards

1
Q

Also known as polypeptides

A

Proteins

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2
Q

What is protein

A

Are organic compounds made of amino acids arranged in a linear chain

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3
Q

The amino acids in a _____ are joined together by the______ between______ and the____ of adjacent amino acids residues

A

Polymer, peptide bonds, carboxyl, amino groups

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4
Q

Importance of proteins

A

Catalyzing biochemical reactions (enzymes), structural and mechanical functions (actin and myosin), cell signaling, immune responses, cell adhesion, cell cycle

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5
Q

Molecules containing an amine group, a carboxylic acid group, and a side chain

A

Amino acids

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6
Q

General formula of proteins

A

RCH (NH2) COOH

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7
Q

Amino acids are___

A

Amphoteric

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8
Q

Amino acids behave as ______ in some reactions and as _______ in others

A

Amines, carboxylic acids

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9
Q

Amino acids are____ to life

A

Critical

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10
Q

Functions of amino acids

A

Building blocks of protein
Intermediates in metabolism

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11
Q

Amino acids are generally classified by the properties of their______ into ____ groups

A

Side chain, 4

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12
Q

The side chain can make an amino acid a

A

Weak acid
Weak base
Hydrophilic-if the side chain is polar
Hydrophobic- if it is non-polar

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13
Q

What is biuret test

A

Detection of the peptide bonds

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14
Q

General test for proteins

A

Biuret test

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15
Q

Biuret test positively identifies the presence of proteins, not less than____

A

two peptides

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16
Q

The reaction of biuret test involves the complex formation of the_____ with _________ in a strongly ________ solution

A

Proteins, Cu2+ ions, alkaline

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17
Q

The_______ (copper sulfate in a strong base) reacts with ______ in proteins to form a _______ complex

A

biuret reagent,peptide bonds, blue to violet

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18
Q

Blue to violet complex also known as

A

Biuret complex

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19
Q

______ peptide bonds atleast required for the formation of the complex

A

2

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20
Q

Biuret reagent is a solution composed of

A

Sodium hydroxide (NaOH)
Potassium hydroxide (KOH)
Hydrated copper (II) sulfate
Potassium sodium tartrate

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21
Q

Positive of biuret test

A

Violet biuret complex

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22
Q

Negative results of biuret test

A

Blue

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23
Q

Xanthoproteic acid test

A

Detection of aromatic amino acids

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24
Q

The test is used to differentiate between aromatic amino acids which gives positive results and other amino acids

A

Xanthoproteic acid test

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25
Q

Amino acids containing an _____ form ______on heating with______ (Nitric acid)

A

Aromatic nucleus, yellow nitro derivatives, Concentrated HNO3

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26
Q

The salts of these derivatives are ____ in color

A

Orange

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27
Q

Xanthoproteic acid is a Test for the presence of amino acids like

A

Tryptophan, phenylalanine, tyrosine, serine, threonine

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28
Q

Negative result for xanthoproteic acid test

A

Absence of aromatic amino acids (tyrosine and tryptophan)
Colorless

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29
Q

Positive result for xanthoproteic acid test

A

Presence of aromatic amino acids (tyrosine and tryptophan)
Dark yellow or orange color

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30
Q

Lead sulfide test

A

Detection of amino acid containing sulfhydryl or thiol group (-SH)

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31
Q

Lead sulfide test is also known as

A

Cysteine test

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32
Q

The reaction in lead sulfide test is specifically given by ________ as in ______ and ______

A

Sulfur group, cysteine,cystine

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33
Q

Group that can be removed by treatment with alkali as sodium sulfide

A

Sulfur group

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34
Q

If _____ are present _____ will precipitate

A

Lead ions, lead sulfide

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35
Q

Oxidized derivative of the amino acid cysteine

A

Cystine

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36
Q

When cysteine is heated with strong alkali like ________(sodium hydroxide). Some of the sulfur is converted to________(Na2S) which can be detected by _______ as_____ from alkaline solution

A

NaOH, sodium sulfide, precipitation, lead sulfide (PbS)

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37
Q

Positive result for lead sulfide test

A

Black precipitate

38
Q

Negative result for lead sulfide test

A

No black precipitate

39
Q

What is hopkins cole test

A

Detection of tryptophan

40
Q

Hopkins cole test is also known as

A

Glyoxylic acid reaction

41
Q

Used for detecting the presence of tryptophan in proteins

A

Hopkins cole test

42
Q

The indole group of tryptophan reacts with _______ in the presence of ______(sulfuric acid) to give a purple color

A

Glyoxylic acid, cone H2SO4

43
Q

Glyoxylic acid is prepared by_______ with______ or ________

A

reducing oxalic acid, magnesium powder, sodium amalgam

44
Q

Exposed to the sunlight also contains glyoxylic acid and can thus be used for Hopkins cole test

A

Glacial acetic acid

45
Q

Positive result for hopkins cole test

A

Purple ring at the junction of two layers
Tryptophan present

46
Q

Negative result of hopkins cole test

A

Absence of purple ring

47
Q

Sakaguchi test

A

Detection of arginine

48
Q

Is used to test for a certain amino acids and protein

A

Sakaguchi test

49
Q

The amino acid that is detected in sakaguchi test is

A

Arginine

50
Q

Since arginine has a_______ in its side chain, it gives a _______ with ______ in the presence of an oxidizing agent like bromine solution

A

Guanidine group, red color, a-naphtol

51
Q

The quantification of arginine is hindered in this test due to the______ of color development and destruction of some________ by the reagent

A

Slow rate, guanidinium

52
Q

Positive result of sakaguchi test

A

Red colored complex
Presence of arginine or a guanidinium compound

53
Q

Negative result of Sakaguchi test

A

No red colored complex
No arginine or a guanidinium compound

54
Q

Biuret test in albumin, gelatin, casein

A

Purple

55
Q

Biuret test in distilled water

A

Sky blue

56
Q

Xanthoproteic acid test in albumin, gelatin, casein

A

Yellow

57
Q

Xanthoproteic acid test in distilled water

A

Clear

58
Q

Cysteine test in albumin

A

Black precipitate

59
Q

Cysteine test in gelatin

A

Yellow

60
Q

Cysteine test in casein

A

Bronze color

61
Q

Cysteine test in distilled water

A

Transparent

62
Q

Hopkins cole test in albumin

A

Purple ring

63
Q

Hopkins cole test in gelatin

A

None

64
Q

Hopkins cole test in casein and albumin

A

Purple ring

65
Q

Hopkins cole test in distilled water

A

None

66
Q

Sakaguchi test in albumin, gelatin, casein

A

Red

67
Q

Sakaguchi test in distilled water

A

Black

68
Q

Amino acids present in albumin

A

Aromatic, Cysteine, Tryptophan, Arginine

69
Q

Amino acids in casein

A

Aromatic, Tryptophan, Arginine

70
Q

Amino acids present in gelatin

A

Aromatic, Arginine

71
Q

Reagent of Biuret test

A

Biuret reagent

72
Q

Biuret test is a test for

A

General test for protein (with at least 2 peptides)

73
Q

Positive result of biuret test

A

Violet complex

74
Q

Reagent of Xanthoproteic acid test

A

Concentrated HNO3 ( Nitric Acid)

75
Q

Xanthoproteic acid test is a test for

A

Aromatic amino acids

76
Q

Positive result for xanthoproteic acid test

A

Dark yellow or orange colored solution

77
Q

Reagent of lead sulfide test

A

Lead (II) acetate

78
Q

Lead sulfide test is a test for

A

Cysteine (sulfhydryl group or thiol group -SH)

79
Q

Positive result for lead sulfide test

A

Black precipitate

80
Q

Hopkins cole test reagent

A

Hopkins cole reagent

81
Q

Hopkins cole test is a test for

A

Tryptophan

82
Q

Positive result for hopkins cole test

A

Purple ring at the junction of two layers

83
Q

Sakaguchi test reagent

A

Sakaguchi reagent( a-naphtol and sodium hypochlorite)

84
Q

Sakaguchi test is a test for

A

Arginine

85
Q

Positive result of sakaguchi test

A

Red colored complex

86
Q

Is a protein catalyst (amylase)

A

Enzyme

87
Q

Is a protein catalyst (amylase)

A

Enzyme

88
Q

Hydrogen peroxide is

A

Toxic to the body

89
Q

Source of salivary amylase

A

Saliva

90
Q

Albumin

A

Secondary structure

91
Q

Levels of protein organization

A

Primary structure, secondary, tertiary, quarternary

92
Q

Two sulfide bonded together

A

Disulfide bonds

Biochem Lab (6 decks)

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