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Biochemistry > Qualitative Reaction of Proteins > Flashcards

Qualitative Reaction of Proteins Flashcards

1
Q

polypeptides with at least
50 amino acid residues and could
have hundreds and even thousands
of amino acid residues

A

proteins

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2
Q

structure of
protein is largely determined by their
amino sequence as postulated by this
dogma

A

Anfinsen’s dogma

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3
Q

Hierarchy of structural organization
of proteins

A

➢ Primary structure (1o
➢ Secondary structure (2o
➢ Tertiary structure (3o
➢ Quaternary structure (4o

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4
Q

amino acid
sequence of polypeptide which starts
at the N-terminal amino acid and
ends with C-terminal amino acid

A

primary structure

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5
Q

refers to the
local folding of a short segment of a
peptide into specific configurations
such as α-helix, β-sheet, or random
coil

A

secondary stucture

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6
Q

over-all threedimensional shape of the protein
which can either be globular or
fibrous in conformation

A

tertiary structure

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7
Q

– association of
the various sub-units of a multimeric
protein

A

quaternary structure

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8
Q

play countless roles
throughout the biological world, from catalyzing chemical reactions to
building structures of all living things

A

protein

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9
Q

made up of carbon,
oxygen, nitrogen, hydrogen, and
sulfur atoms

A

amino acid

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10
Q

– interact with
oppositely charged amino acid or
water

A

charged amino acid

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11
Q

protein chian fold into this
can form regular patterns of
hydrogen bonds between the
backbone atoms of nearby amino
acids

A

alpha-helix

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12
Q

backbone atoms of the
chain can interact side-by-side to
form

A

beta-sheets

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13
Q

forms a pocket to hold
heme, a small molecule with an iron
atom at the center that binds oxygen

A

hemoglobin

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14
Q

its flexible arms protect
the body from disease by recognizing
and binding to foreign molecules and
thus preventing the viral RNA or DNA
to enter the cell

A

antibodies

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15
Q

forms a strong triple helix
that is used throughout the body for
structural support

A

collagen

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16
Q

moves ions across
cell membranes allowing the
synchronized contraction of muscles

A

calcium pump

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17
Q

small, stable protein that
can easily maintain its shape while
travelling through the blood to
regulate blood sugar level

A

insulin

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18
Q

enzyme that has a
catalytic site that begins the
breakdown of carbohydrates in our
saliva

A

alpha-amylase

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19
Q

forms a hollow shell that
stores iron from our food

A

ferritin

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20
Q

put together a model
of myoglobi

A

John Kendrew

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21
Q

proteins are made up
of these

A

amino acid

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22
Q

used to detect the
presence of a peptide bond and uses
alkaline/basic copper sulfate reagent

A

biuret test

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23
Q

what does biuret test uses as an reagent

A

alkaline
basic copper sulfate

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24
Q

forms a
coordination complex with the
nucleophilic nitrogen atom of
the peptide bond which
manifests as violet complex

A

copper ion

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25
Q

violex complex is called what in biuret test

A

biurety complex

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26
Q

color of biuret when negative

A

blue

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27
Q

color of biuret when positive

A

deep purple

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28
Q

– used for the
detection of free amine on amino
acids or peptides where ninhydrin
reagent forms an intense violet
colored complex called Ruhemann’s
purple

A

Ninhidyrin test

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29
Q

violet colored complex in ninhydrin test

A

Ruhemann’s purple

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30
Q

is a chemical test that can differentiate between an alpha-amino group and a free amino acid.

A

ninhydrin test

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31
Q

In this test, ninhydrin is used as an oxidizing/reducing agent that reacts with the amino group of the analyte

A

oxidizing

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32
Q

positive ninhydrin test is what color

A

purple-colored complex

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33
Q

what is the color of ninhydrin when proline is present

A

yellow

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34
Q

Proline is an _____ and it reacts with ninhydrin to form a yellow-colored complex

A

imino acid

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35
Q

This is because the reaction of proline with ninhydrin yields an ___ salt, which is yellow-orange in colo

A

iminium

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35
Q

used to
distinguish the presence of
tryptophan or tyrosine which forms
yellow-colored product with nitric
acid

A

Xanthoproteic test

36
Q

tryptophan or tyrosine forms a yellow-coloredp roduct with what reagent

A

nitric acid

37
Q

what structure of these amino
acids reacts with nitric acid
forming a yellow by-product

A

benzene ring

38
Q

used to confirm the
presence of tyrosine by the formation
of reddish-brown product with
mercury in nitrous acid

A

Millons test

39
Q

reagent that tyrosine reacts with in Millons test

A

acificied mercuric sulphate solution

40
Q

Detects tyrosine by the
reaction of its phenolic group
with the reagents, producing a
reddish-brown complex

A

millons test

41
Q

used for the
detection of tryptophan which forms
a violet ring upon reaction with
glyoxylic acid and conc. Sulfuric acid

A

hopkins-cole test

42
Q

Detects tryptophan by the
reaction of its indole ring
reacts with the reagents

A

hopkins-cole test

43
Q

Manifested in the formation of
violet ring in between the layer
of the sample and sulfuric acid

A

positive hopkins-cole test

44
Q

reagent in Hopkins-cole test

A

glyoxylic acid

45
Q

disruption of these
stabilizing forces and bonds in a
protein that results to the disruption of its native conformation and
subsequent loss of its biological
function

A

denaturation

46
Q

Physical manifestations that can
denature a protein

A

mechanical agitation
heat

47
Q

Chemical agents that can denature a
protein:

A

➢ Acids
➢ Bases
➢ Salts
➢ Organic solvents
➢ Detergent
➢ Alkaloids
➢ Heavy metals

48
Q

Chaotropic agents include (5)

A

– guanidine
HCl
urea,
βmercaptoethanol,
dithioeitol

49
Q

can disrupt specific
stabilizing bonds or forces in
the protein which leads to
alternation in its structure as
manifested by the
precipitation of the protein
from the solution

A

chaotropic agents

50
Q

Stabilizing bonds or force in proteins

A

H-bond
Salt bridge
Hydrophobic interaction
disulfide bond

51
Q

Fill in the blanks

Carefully separate egg white from
yolk of one medium-sized chicken
egg. Discard _____. Measure the
volume of egg using a ______ . Transfer to a 250 ml
beaker and dilute with equal
volume of _____ ______. Use
as a sample for subsequent
analysis

A

yolk
graduated cylinder
phosphate buffer

52
Q

Transfer _____ mL of the egg white
solution to _____separate test tubes
and label them properly. Add the
ff reagents to the respective test
tubes:

A

2 mL
5 test tubes

53
Q

Test tube 1 – 2.00 ml of
____solution, heat for
5 minutes in water bath or
until a color change is
observed

A

ninhydrin solution

54
Q

test tube 2 – 5 drops of
concentrated ___ _____
(xanthoproteic test), heat
for 5 minutes in water bath
or until a color change is
observed

A

nitric acid

55
Q

Test tube 3 – 5 drops of
______ _____, heat for 5
minutes in water bath or
until precipitate is formed

A

Millon’s reagent

56
Q

Test tube 4 – 5 drops of
_____ ____ (HopkinsCole reagent), tilt the tube
slightly and carefully add
2.0 mlo of concentrated
sulfuric acid to form two
layers. Wait for color
change

A

glyoxylic acid

57
Q

Test tube 5 – 2 mL of ______
solution and 1 mL of 0.200
M _____. Shake vigorously
and incubate until a color
change is observed

A

biuret
NaOH

58
Q

Transfer 2 mL of the egg white
solution to _ separate test tubes
and label them properly. Add the
following reagents to the
respective test tubes

A

8

59
Q

Test tube 1 – 0.200 M ___
drop by drop until change
occurs

A

HCl

60
Q

test tube 2 – 0.200 M ____
drop by drop until change
occurs

A

NaOH

61
Q

Test tube 3 – 0.200 M _____
____drop by drop until
change occurs

A

lead acetate

62
Q

Test tube 4 – 0.200 M _____
drop by drop until change
occurs

A

urea

63
Q

Test tube 5 – 0.200 M ____
acid drop by drop until
change occurs

A

tannic

64
Q

test 6 – 70% ____
drop by drop until change
occurs

A

ethanol

65
Q

Test tube 7 – _____in water
bath until change occurs

A

heat

66
Q

Test tube 8 – ______
vigorously until change
occurs

A

shake

67
Q

– increases kinetic energy,
causing atoms of proteins to vibrate.
The vibrating motion disrupts or
breaks the weak hydrogen bonds and
dispersion forces

A

heat

68
Q

The accelerated vibration can
disrupt the _____ ______ ,
_______ ______, as
well as ___ _____forces,
causing the unfolding of
protein’s 3D structure

A

hydrogen bond
hydrophobic interactions
van der waals

69
Q

a hydrogen bonds to
polarized areas of charge, such as
peptide groups.

A

urea

70
Q

Mutual influence weakens the
intermolecular bonds and
interactions, weakening the
overall secondary and tertiary
structure

A

urea

71
Q

capable of engaging in
intermolecular hydrogen bonding
with protein molecules, disrupting
intramolecular hydrogen bonding
within the protein

A

ethanol

72
Q

combine with positively
charged amino groups in proteins to
disrupt ionic bonds

A

tannic acid

73
Q

normally, a person hav

A

protein

74
Q

– large amount of protein
in urine may mean that you have a
problem with your kidneys

A

proteinuria

75
Q

Early sign of chronic kidney
diseases (CKD

A

proteinuria

76
Q

Needed for the
synthesis of proteins

A

phenylalanine

77
Q

Important precursor
of amino acid Ltyrosine (Tyr)

A

phenyalanine

78
Q

Used as an energy
fuel

A

phenylalanine

79
Q

too much of this when converted into
phenylpyruvate, and
the individual usually
develops seizures,
brain damage, and
mental retardation

A

phenyalanine

80
Q

too little of this causes growth
failure, loss of
muscle mass, and
organ damage

A

phenylalanine

81
Q

Play a significant role
in the regulation of
energy metabolism,
locomotor activity,
and eating behavior

A

tyrosine

82
Q

too much of this can cause migraine headaches
and hyperthyroid
conditions

A

tyrosine

83
Q

too little of this is associated with
behavioral and
learning disorders,
depression, anxiety,
and inability to deal
with stress

A

tyrosine

84
Q

role in
brain serotonin
synthesis is an
important factor
involved in mood,
behavior, and
cognition

A

tryptophan

85
Q

high levels is
associated with
headaches and
selective serotonin
reuptake inhibitor
treatmen

A

tryptophan

86
Q

Low levels are
commonly correlated
with depression,
insomnia, and
schizophrenia

A

tryptophan

87
Q
A

Biochemistry (12 decks)

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