Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry LAB > COLOR REACTIONS OF PROTEINS AND AMINO ACIDS > Flashcards

COLOR REACTIONS OF PROTEINS AND AMINO ACIDS Flashcards

1
Q

1 ml = ???

A

20 drops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Few drops = ???

A

3 to 5 drops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Unspecified time for heating

A

5 mins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

the building blocks of proteins

A

Amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

The general reactions of amino acids are mostly due to the
presence of two functional groups namely __________ and __________

A

carboxyl (-COOH) group and amino (-NH2) group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

limitation of reaction tests

A

some non-protein substances can also give positive response to some of the
color tests

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q
  • NH3
A

Amino group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q
  • COOH
A

Carboxylic acid group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

it is where all four species are attached

A

(alpha) α - carbon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Side chain

A

R - group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

simplest amino acid

A

aminoacetic acid → glycine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

two amino acids

A

Dipeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

three amino acids

A

Tripeptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

50 amino acids or more

A

Proteins or polypeptides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

General Steps in Peptide Bond Formation

A
  1. Amino group on one amino acid molecule + carboxyl group on another amino acid
  2. Release of a molecule of water and formation of a peptide bond.
  3. The reactive amino group on the left and the reactive carboxyl group on the right can still react with additional amino acids to lengthen the peptide.
  4. The process can continue until thousands of units have joined, resulting in large proteins.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

pH at which an amino acid exists as a Zwitterion

A

Isoelectric point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

hydrogen is in excess

A

acid solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

OHion is in excess

A

alkaline solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Product of internal transfer of a hydrogen ion from the -COOH group to the -NH2 group to leave an ion with both a negative charge and a positive charge.

A

zwitterion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

isoelectric points: Acidic amino acids

A

aspartic acid (2.8), glutamic acid (3.2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

isoelectric points: Neutral amino acids

A

(5.0 to 6.3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

isoelectric points: Basic amino acids

A

lysine (9.7), arginine (10.8), histidine (7.6)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

base + amino acid in zwitterion form

A

Amino acid as an acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

acid + amino acid in zwitterion

A

Amino acid as base

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

zwitterion form:

A

ionized form (-COO-) of carboxylic group - base

ionized form (-NH3+) of amino group - acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

(alpha) α - carbon other name

A

chiral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

four different constituents/species and that the α - carbon is asymmetric.

A

chiral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

α - carbon shape

A

asymmetric → two possible, non-superimposable, mirror images of the amino acids.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Clockwise rotation

A

“dextrorotatory”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Counter clockwise:

A

“levorotatory”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

a pair of molecules that exist in two forms that are mirror images of one another but cannot be superimposed one upon the other.

A

Enantiomers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Enantiomeric molecules

A

optical property/optical activity → ability to rotate the plane of polarized light

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

All common amino acids are the _________

A

L-enantiomer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

capacity to interact with water

A

Polarity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Classification of Amino Acids Based on Polarity

A

(1) nonpolar,
(2) polar-neutral,
(3) polar-acidic, and
(4) polar-basic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

hydrophobic (“water-fearing”); not attracted to water molecules

A

Nonpolar Amino Acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Nonpolar Amino Acids

A
  1. Glycine
  2. Alanine
  3. Valine
  4. Leucine
  5. Isoleucine
  6. Proline
  7. Phenylalanine
  8. Methionine
  9. Tryptophan
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

In solution at physiological pH - side chain of this amino acid is neither acidic nor basic.

A

Polar neutral amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

More soluble in water than the nonpolar amino acids as, in each case, the R group present can form hydrogen bond to water

A

Polar neutral amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Polar neutral amino acids

A
  1. Serine
  2. Cysteine
  3. Threonine
  4. Asparagine
  5. Glutamine
  6. Tyrosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

In solution at physiological pH - side chain of this amino acid bears a negative charge; the side-chain carboxyl group has lost its hydrogen atom.

A

Polar acidic amino acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Polar acidic amino acid

A
  1. Aspartic acid
  2. Glutamic Acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

In solution at physiological pH - side chain of this amino acid bears a positive charge; the nitrogen atom of the amino group has accepted a proton.

A

Polar basic amino acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Polar basic amino acid

A
  1. Histidine
  2. Lysine
  3. Arginine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

side chain is H or alkyl (nonpolar)

A
  1. Glycine
  2. Alanine
  3. Valine
  4. Leucine
  5. Isoleucine
  6. Phenylalanine
  7. Proline
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

side chain contains an -OH group (hydroxyl)

A
  1. Serine
  2. Threonine
  3. Tyrosine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

side chain contains sulfur

A
  1. Cysteine
  2. Methionine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

side chain contains nonbasic nitrogen

A
  1. Asparagine
  2. Glutamine
  3. Tryptophan
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Side chain is acidic

A
  1. Aspartic acid
  2. Glutamic acid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

side chain is basic

A
  1. Lysine
  2. Arginine
  3. Histidine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

properties and reactions due to

A

Basic amino group and an acidic carboxyl group
Side chains
Dipolar nature/zwitterion form

52
Q

Solubility

A

generally soluble in water and insoluble in non-polar organic solvents; -> polar water molecules and the zwitterions

53
Q

Decomposition and melting tend _________ range

A

200 - 300°C

54
Q

__________ solids with __________ melting points;

A

crystalline; high

55
Q

Usual taste of amino acid

A

sour or umami

56
Q

tasteless

A

Leucine

57
Q

Sweet

A
  1. Glycine
  2. Alanine
  3. Valine
58
Q

Bitter

A
  1. Arginine
  2. Isoleucine
59
Q

Chemical Reactions

A
  1. Reaction due to the carboxylic group (-COOH)
  2. Reaction due to the amino group (-NH2)
60
Q

Reaction due to the carboxylic group (-COOH)

A

A. Salt formation: Amino + amino
B. Salt formation: Base
C. Ester Formation - Alcohol
D. Decarboxylation
E. Reaction to ammonia

61
Q
  1. Reaction due to the amino group (-NH2)
A

A. Salt formation - Acid
B. Reaction with Ninhydrin
C. Transamination
D. Oxidative deamination

62
Q

zwitterion in low pH

A

cation

63
Q

zwitterion in high pH

A

anion

64
Q

they can act either as a base or an acid

A

amphoteric

65
Q

Formation of peptide is a _________ process

A

Condensation

66
Q

Optical Activity is determined by

A

Polarimeter

67
Q

L-amino acid taste

A

sweet or bitter taste

68
Q

D-amino acid

A

Sweet

69
Q

Salt is formed by

A

acid-base neutralization reaction

70
Q

Salt formation

A

amino groups behave as bases and combine with acids

Amino acids form salts (COONa) with base

Amino acids can form esters (COOR) with alcohols

71
Q

removes a carboxyl group and releases carbon dioxide (CO2)

A

Decarboxylation

72
Q

could be used to develop latent fingerprints

A

ninhydrin

73
Q

α-amino acids react with ninhydrin to form a

A

purple, blue or pink color complex (Ruhemann’s purple)

proline and hydroxyproline = yellow color

74
Q

Decarboxylation

A

Amino acid - (enzymes) -> amine

75
Q

Carboxyl group of dicarboxylic amino acid reacts with NH3 to form an amide

A

Reaction with ammonia

76
Q

Reduce ninhydrin

A

hydrindantin

77
Q

transfer of an amino group from an amino acid to a keto acid to form a new amino acid

A

Transamination

78
Q

Transamination is catalyzed by the family of enzymes called

A

transaminase

79
Q

transaminases require the participation of aldehyde-containing enzyme called

A

pyridoxal phosphate (PLP)

80
Q

amino acid is converted into the corresponding keto acid by the removal of the amine functional group (NH2)

provide NH3 + for urea synthesis and a-keto acids for a variety of reactions

occurs primarily on glutamic acid

A

Oxidative deamination

80
Q

amino acid is converted into the corresponding keto acid by the removal of the amine functional group (NH2)

provide NH3 + for urea synthesis and a-keto acids for a variety of reactions

occurs primarily on glutamic acid

A

Oxidative deamination

80
Q

amino acid is converted into the corresponding keto acid by the removal of the amine functional group (NH2)

provide NH3 + for urea synthesis and a-keto acids for a variety of reactions

occurs primarily on glutamic acid

A

Oxidative deamination

81
Q

amino acid is converted into the corresponding keto acid by the removal of the amine functional group (NH2)

provide NH3 + for urea synthesis and a-keto acids for a variety of reactions

occurs primarily on glutamic acid

A

Oxidative deamination

82
Q

BIURET TEST positive result

A

Color produced may vary from pink to blue

83
Q

BIURET TEST Reactive group:

A

Proteins and peptides with at least two peptide linkages give positive
biuret test;

histidine

84
Q

BIURET TEST Principle:

A

alkaline copper (II) sulphate + peptides/proteins (–CONH2) → violet complex

85
Q

NINHYDRIN TEST Positive Result:

A

Intense blue or purple compound

(proline and hydroxyproline) = yellow color

86
Q

NINHYDRIN TEST Reactive group

A

α-amino group; peptides

87
Q

NINHYDRIN TEST Principle:

A

▪ Oxidative deamination and decarboxylation.

Triketohydrindenehydrate + alpha-a.a./peptides → intense blue color or purple color

Imino acids (proline and hydroxyproline) + ninhydrin → yellow color

88
Q

XANTHOPROTEIC TEST Positive Result:

A

orange colored derivative salts

89
Q

XANTHOPROTEIC TEST Reactive group:

A

aromatic ring of tyrosine and tryptophan

90
Q

XANTHOPROTEIC TEST Principle:

A

tyrosine/tryptophan + HNO3→ nitration of the phenyl group → yellow derivatives + alkali→ orange colored derivative salts

91
Q

MILLON’S TEST Positive Result:

A

old rose-colored complex

92
Q

MILLON’S TEST Reactive group:

A

phenolic ring of tyrosine

93
Q

MILLON’S TEST Principle:

A

Tyrosine + NaNO2 → nitration of hydroxyphenyl group of
tyrosine + mercuric sulfate → old rose colored salt

94
Q

MILLON’S TEST Interfering compounds:

A

alkalis and chlorides

95
Q

MILLON’S TEST Remedy:

A

addition of sodium nitrite or extra mercuric sulphate

96
Q

HOPKINS-COLE REACTION Positive Result:

A

violet complex

97
Q

HOPKINS-COLE REACTION Reactive group:

A

indole ring of tryptophan

98
Q

HOPKINS-COLE REACTION Principle:

A

▪ a.a. (indole group) + glyoxylic acid (aldehyde group) →
VIOLET/PURPLE COMPLEX

99
Q

HOPKINS-COLE REACTION Interfering compounds:

A

nitrites, nitrates, chlorides and chlorates

100
Q

HOPKINS-COLE REACTION Remedy:

A

pure sulfuric acid

101
Q

BROMINE WATER TEST Positive Result:

A

pinkish lavender complex

102
Q

BROMINE WATER TEST Reactive group:

A

indole ring of tryptophan

103
Q

BROMINE WATER TEST Principle:

A

▪ Bromine water + Tryptophan + n-amyl alcohol → PINKISH LAVENDER COMPLEX (soluble at alcohol layer)

104
Q

BROMINE WATER TEST Note:

A

color of excess reagent→ masked pinkish lavender color

Remedy: accuracy in amounts of reagents

105
Q

PAULY REACTION Positive Result:

A

highly colored dyes

106
Q

PAULY REACTION Reactive group:

A

phenolic ring in tyrosine; imidazole ring in histidine

107
Q

PAULY REACTION Principle:

A

(diazotization)

108
Q

LEAD ACETATE REACTION Positive Result:

A

black precipitate

109
Q

LEAD ACETATE REACTION Reactive group:

A

Sulfhydril (-SH) group of cysteine, disulfide bond in cystine

110
Q

LEAD ACETATE REACTION Note:

A

methionine has sulphide (-S), not sulfhydryl group (-SH), thus it will yield a negative result

111
Q

NITROPRUSSIDE REACTION Positive Result:

A

▪ Red compound indicates free sulfhydryl group
▪ Purple compound indicates disulfide bonds

112
Q

NITROPRUSSIDE REACTION Reactive group:

A

▪ sulfhydril (-SH) group in cysteine
▪ disulfide bond in cystine

113
Q

SAKAGUCHI REACTION Positive Result:

A

red or orange color

114
Q

SAKAGUCHI REACTION Reactive group:

A

guanidino group of arginine

115
Q

SAKAGUCHI REACTION Principle:

A

Arginine + a-naphthol and sodium hypobromite →
red or orange colored complex

116
Q

SCHIFF’S TEST Positive Result:

A

magenta/pink color

117
Q

SCHIFF’S TEST Reactive group:

A

compounds containing aldehyde group; amino group of lysine

118
Q

SCHIFF’S TEST

A

Qualitative test for aldehydes

1st lysine + aldehyde → Schiff base
2nd Schiff base + Schiff reagent → Schiff Adduct (red or orange compound)

119
Q

FOLIN’S MCCARTHY SULLIVAN TEST Positive Result:

A

Red colour

120
Q

FOLIN’S MCCARTHY SULLIVAN TEST Reactive group:

A

Methionine

121
Q

FOLIN’S MCCARTHY SULLIVAN TEST Principle:

A

▪ Methionine + Sodium nitroprusside + HCl → red color

122
Q

ISATIN TEST Positive Result:

A

blue colored product

123
Q

ISATIN TEST Reactive group:

A

imino group of proline/hydroxyproline

124
Q

ISATIN TEST Principle:

A

Proline and hydroxyproline + isatin reagent → blue-colored
product.

Biochemistry LAB (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions