Experiment #14: COLOR REACTION OF PROTEINS Flashcards

(92 cards)

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
Amino acids containing an _____ form ______on heating with______ (Nitric acid)
Aromatic nucleus, yellow nitro derivatives, Concentrated HNO3
26
The salts of these derivatives are ____ in color
Orange
27
Xanthoproteic acid is a Test for the presence of amino acids like
Tryptophan, phenylalanine, tyrosine, serine, threonine
28
Negative result for xanthoproteic acid test
Absence of aromatic amino acids (tyrosine and tryptophan) Colorless
29
Positive result for xanthoproteic acid test
Presence of aromatic amino acids (tyrosine and tryptophan) Dark yellow or orange color
30
Lead sulfide test
Detection of amino acid containing sulfhydryl or thiol group (-SH)
31
Lead sulfide test is also known as
Cysteine test
32
The reaction in lead sulfide test is specifically given by ________ as in ______ and ______
Sulfur group, cysteine,cystine
33
Group that can be removed by treatment with alkali as sodium sulfide
Sulfur group
34
If _____ are present _____ will precipitate
Lead ions, lead sulfide
35
Oxidized derivative of the amino acid cysteine
Cystine
36
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
NaOH, sodium sulfide, precipitation, lead sulfide (PbS)
37
Positive result for lead sulfide test
Black precipitate
38
Negative result for lead sulfide test
No black precipitate
39
What is hopkins cole test
Detection of tryptophan
40
Hopkins cole test is also known as
Glyoxylic acid reaction
41
Used for detecting the presence of tryptophan in proteins
Hopkins cole test
42
The indole group of tryptophan reacts with _______ in the presence of ______(sulfuric acid) to give a purple color
Glyoxylic acid, cone H2SO4
43
Glyoxylic acid is prepared by_______ with______ or ________
reducing oxalic acid, magnesium powder, sodium amalgam
44
Exposed to the sunlight also contains glyoxylic acid and can thus be used for Hopkins cole test
Glacial acetic acid
45
Positive result for hopkins cole test
Purple ring at the junction of two layers Tryptophan present
46
Negative result of hopkins cole test
Absence of purple ring
47
Sakaguchi test
Detection of arginine
48
Is used to test for a certain amino acids and protein
Sakaguchi test
49
The amino acid that is detected in sakaguchi test is
Arginine
50
Since arginine has a_______ in its side chain, it gives a _______ with ______ in the presence of an oxidizing agent like bromine solution
Guanidine group, red color, a-naphtol
51
The quantification of arginine is hindered in this test due to the______ of color development and destruction of some________ by the reagent
Slow rate, guanidinium
52
Positive result of sakaguchi test
Red colored complex Presence of arginine or a guanidinium compound
53
Negative result of Sakaguchi test
No red colored complex No arginine or a guanidinium compound
54
Biuret test in albumin, gelatin, casein
Purple
55
Biuret test in distilled water
Sky blue
56
Xanthoproteic acid test in albumin, gelatin, casein
Yellow
57
Xanthoproteic acid test in distilled water
Clear
58
Cysteine test in albumin
Black precipitate
59
Cysteine test in gelatin
Yellow
60
Cysteine test in casein
Bronze color
61
Cysteine test in distilled water
Transparent
62
Hopkins cole test in albumin
Purple ring
63
Hopkins cole test in gelatin
None
64
Hopkins cole test in casein and albumin
Purple ring
65
Hopkins cole test in distilled water
None
66
Sakaguchi test in albumin, gelatin, casein
Red
67
Sakaguchi test in distilled water
Black
68
Amino acids present in albumin
Aromatic, Cysteine, Tryptophan, Arginine
69
Amino acids in casein
Aromatic, Tryptophan, Arginine
70
Amino acids present in gelatin
Aromatic, Arginine
71
Reagent of Biuret test
Biuret reagent
72
Biuret test is a test for
General test for protein (with at least 2 peptides)
73
Positive result of biuret test
Violet complex
74
Reagent of Xanthoproteic acid test
Concentrated HNO3 ( Nitric Acid)
75
Xanthoproteic acid test is a test for
Aromatic amino acids
76
Positive result for xanthoproteic acid test
Dark yellow or orange colored solution
77
Reagent of lead sulfide test
Lead (II) acetate
78
Lead sulfide test is a test for
Cysteine (sulfhydryl group or thiol group -SH)
79
Positive result for lead sulfide test
Black precipitate
80
Hopkins cole test reagent
Hopkins cole reagent
81
Hopkins cole test is a test for
Tryptophan
82
Positive result for hopkins cole test
Purple ring at the junction of two layers
83
Sakaguchi test reagent
Sakaguchi reagent( a-naphtol and sodium hypochlorite)
84
Sakaguchi test is a test for
Arginine
85
Positive result of sakaguchi test
Red colored complex
86
Is a protein catalyst (amylase)
Enzyme
87
Is a protein catalyst (amylase)
Enzyme
88
Hydrogen peroxide is
Toxic to the body
89
Source of salivary amylase
Saliva
90
Albumin
Secondary structure
91
Levels of protein organization
Primary structure, secondary, tertiary, quarternary
92
Two sulfide bonded together
Disulfide bonds