Proteins Flashcards

1
Q

The word protein is derived from the Greek word

A

proteios

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2
Q

The word protein is derived from the Greek word, “proteios” which means

A

primary

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3
Q

are used for bodybuilding; ____ molecules carry out all the major structural and functional aspects of the body.

A

protein

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4
Q

Abnormality in protein structure will lead to

A

molecular diseases

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5
Q

Proteins contain what major elements (4)

A

carbon
hydrogen
oxygen
nitrogen

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6
Q

minor constituents of protein

A

sulfur
phosphorus

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7
Q

On average, the nitrogen content of ordinary proteins is __% by weight

A

16

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8
Q

All proteins are polymers of

A

amino acids

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9
Q

chain of amino acids bound to one another by peptide bonds

A

protein

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10
Q

parts of an amino acid (4)

A

central carbon
carboxylic acid group
amino group
side chain

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11
Q

five amino acids that we can get from food but we can also make ourselves are called what?

also give what are those

A

non-essential amino acids

alanine
asparagine
aspartic acid
glutamic acid
serine

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12
Q

amino acids that healthy bodies can make them under normal circumstances, but can’t in starvation or certain inborn errors of metabolism (6)

A

cysteine
arginine
glutamine
glycine
proline
tyrosine

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13
Q

nine amino acids that we can only get from food (what are they called as well)

A

essential amino acids

histidine
isoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valnie

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14
Q

provide essential amino acids that allows the body to produce proteins, hormones, and other important molecules

A

dietary proteins

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15
Q

process that begin when the food reaches the stomach wherein HCl denatures the protein unfolding it and making the amino acid chain more accessible to enzymatic action

A

proteolysis

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16
Q

made by gastric chief cells, cleaves any available protein into oligopeptide chains

A

pepsin

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17
Q

move into the duodenum where a second set of digestive enzymes made by the pancreas further chops these into tripeptides, dipeptides, and individual amino acids

A

oligopeptides

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18
Q

cells where dipeptides and tripeptides are converted into amino acids

A

intestinal cells

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19
Q

all nine essential amino acids are provided by what food

A

animal-based protein

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20
Q

provide high amount of some while low amounts of others are provided in these foods

A

plant foods

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21
Q

what bridge is formed when an alphacarboxyl group of one amino acid reacts with the alpha amino acid group of another amino acid

A

CO-NH bridge

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22
Q

synthesized by the polymerization of amino acids through peptide bonds

A

proteins

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23
Q

two amino acids combined to form a what

A

dipeptide

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24
Q

three amino acids form a what

A

tripeptide

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25
Q

four amino acids will form what

A

tetrapeptide

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26
Q

a few amino acids together will make a what

A

oligopeptide

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27
Q

combination of 10-50 amino acids forms an

A

polypeptide

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28
Q

long polypeptide chains containing more than 50 amino acids are called ___

A

proteins

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29
Q

different levels of structural organization of proteins

A

primary
secondary
tertiary
quaternary

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30
Q

means the order of amino acids in the polypeptide chain and the location of disulfide bonds, if any

what structure

A

primary

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31
Q

is the steric relationship of amino acids, close to each other

A

secondary structure

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32
Q

denotes the overall arrangement and inter-relationship of the various regions, or domains of a single polypeptide chain

A

tertiary structure

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33
Q

results when the proteins cosist of two or more polypeptide chains held together by non-covalent forces

A

quaternary structure

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34
Q

the primary structure is maintained by what bonds of the peptide linkages

A

covalent bonsd

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35
Q

partial double bond

A

peptide bond

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36
Q

C-N bond is ‘trans’ or ‘cis’

A

trans

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37
Q

distance between peptide bonds

A

1.32A

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38
Q

angles of rotation of side chains of the peptide bonds are known as

A

Ramachandran angles

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39
Q

in a polypeptide chain, at one end there will be one free alpha amino group called

A

amino terminal (N-terminal) end

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40
Q

amino acid contributing the alpha-amino group is named as what amino acid

A

first amino acid

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41
Q

the other end of the poylpeptide chain where there is a free alpha carboxyl group

A

carboxy terminal end (c-terminal)

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42
Q

amino acid residues in polypeptides are named by changing the suffix “-ine” to what

A

-yl

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43
Q

branching points in the chains may be produced by interchain

A

disulphide bridges

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44
Q

bond between the disulphide bridges are what kind

A

covalent

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45
Q

the covalent disulphide bonds between different polypeptide chains in the same protein are called

A

interchain

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46
Q

covalent disulphide bonds between different polypeptide chains in portions of same polypeptide chain

A

intrachain

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47
Q

rarely, instead of the alpha COOH group, this part of the glutamic acid may enter into peptide formation

A

gamma carboxyl

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48
Q

is used to denote such peptide bond formed by carboxyl group, other than that present in alpha position

A

pseudopeptide

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49
Q

protein in circular form

A

gramicidin

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50
Q

has two polypeptide chains, a chain of glycine (21 amino acids) b chain of phenylalanine (30 amino acids)

A

insulin

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51
Q

how many interchain disulfide bonds are there in insulin

A

two

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52
Q

what cysteine in A chain and B chain are connected

A

7th and 19th

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53
Q

intrachain disulfide bond between chain a and b is located in what

A

chain a - 6th and 11th

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54
Q

beta cells of pancreas synthesize insulin as prohormone called

A

proinsulin

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55
Q

single polypeptide chain with 86 amino acids

A

proinsulin

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56
Q

biologically active insulin (2 chains) is formed by the removal of what portion of proisulin before release

A

central

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57
Q

a protein with a specific primary structure will automatically form what shape

A

three-dimensional

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58
Q

means the spacial relationship of every atom in a molecule

A

conformation

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59
Q

denotes the spatial relationship between particular atoms

A

configuration

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60
Q

denotes the configurational relationship between residues, which are about 3-4 amino acids apart in the linear sequence

A

secondary structure

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61
Q

secondary and tertiary levels of protein structure are preserved by ___

A

noncovalent forces or bonds

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62
Q

noncovalent forces/bonds in secondary and tertiary structure of proteins

A

hydrogen bonds
electrostatic bonds
hydrophobic interactions
van der Waals forces

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63
Q

most common and stable conformation for a polypeptide chain (secondary structure)

A

alpha helix

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64
Q

in proteins like ___ and ____, the alpha helix is abundant

A

hemoglobin
myoglobin

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65
Q

structure of alpha helix wherein he polypeptide bonds form the back-bone and side chains of amino acids extending outward

A

spiral structure

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66
Q

alpha structure is stabilized by what bonds between NH and C=O groups of the main chain

A

hydrogen bonds

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67
Q

alpha-helix is generally left/right handed

A

right

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68
Q

this configuration of alpha helix is rare, because amino acids found in proteins are of L-variety

A

left handed

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69
Q

the polypeptide chains in this is almost fully extended, the distance between adjacent amino acids is 3.5A

A

Beta-Pleated Sheet

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70
Q

stabilized by hydrogen bonds between NH and C=O groups of neighboring polypeptide segments

what secondary structure

A

beta-pleated sheet

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71
Q

major structural motif in proteins like silk fibroin, flavodoxin, and carbonic anhydrase

A

beta-pleated sheet

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72
Q

fibroin is parallel/anti-parallel/both?

A

anti-parallel

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73
Q

flavodoxin is parallel/anti-parallel/both?

A

parallel

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74
Q

carbonic anhydrase is parallel/anti-parallel/both?

A

both

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75
Q

may be formed in many proteins in beta-pleated sheet due to the abrupt U-turn folding of the chain

A

beta bends

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76
Q

what stabilizes beta bends in b-pleated sheet?

A

intrachain disulfide bridges

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77
Q

denotes three dimensional structure of the whole protein

A

tertiary structure

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78
Q

defines the steric relationship of amino acids which are far apart from each other in the linear sequence, but are close in three-dimensional

A

tetriary structure

79
Q

aggregated polypeptides in a functional protein

A

quaternary structure

80
Q

forces that keep quaternary structure (4)

A

hydrogen bonds
electrostatic bonds
hydrophobic bonds
van der Waals forces

81
Q

depending on the number of polypeptide chain, the protein may be termed as

1- chain
2 chain
4 chhain

A

monomer
dimer
tetramer

82
Q

each polypeptide chain is termed as a __

A

subunit, monomer

83
Q

contain two copies of the same polypeptide chain

A

homodimer

84
Q

contains two different types of polypeptides as a functional unit

A

heterodimer

85
Q

creatine kinase (CK) is what

monomer/dimer/tetramer

A

dimer

86
Q

lactate dehyrodgenase is what

monomer/dimer/tetramer

A

tetramer

87
Q

structural conformation that provides and maintains the functional characteristics

A

three-dimensional

88
Q

catalyses the reversible hydration of carbon dioxide

A

carbonic anhydrase

89
Q

structural motif present in myoglobin

A

alpha helix and beta pleated sheet

90
Q

structural motif present in collagen

A

triple helix

91
Q

structural motif present in keratin

A

coiled coil

92
Q

structural motif present in elastin

A

no specific motif

93
Q

motif present in superoxide dimutase

A

antiparallel beta pleated sheet

94
Q

transporter of oxygen that is a tetrameric protein, with each monomer having a heme unit

A

hemoglobin

95
Q

binding of H+ and CO2 promotes the release of what in heme

A

O2

96
Q

allosteric interaction that binds H+ and CO2 to heme to release oxygen

A

Bohr effect

97
Q

most abundant protein in mammals and is the main fibrous component of skin, bone, tendon, cartilage, and teeth

A

collagen

98
Q

forms a superhelical cable where 3 polypeptide chains are wound around itself

A

collagen

99
Q

in collagen, every 3rd residue is what

A

glycine

100
Q

replacement of central glycine in collagen can result to what

A

brittle bone disesase

101
Q

the triple helix of ___ is stabilized by the steric repulsion of the rings of hydroxyproline and also by hydrogen bonds between them

A

collagen

102
Q

in this deficiency, failure oh hydroxylation of proline/lysine lead to reduced hydrogen bonding and consequent weakness of collagen

A

vitamin C deficiency

103
Q

in collagen, this is responsible for its tensile strength

A

quarter staggered triple helical structure

104
Q

heat denatured collagen

A

gelatin

105
Q

mammals contain what kind of keratin

A

alpha-keratin

106
Q

classified into soft and hard depending on sulfur content

A

keratin

107
Q

residues that are responsible for disulfide bridge formation which confers characteristic for each type of protein

A

cysteine

108
Q

have low sulfur content, present in skin

A

soft keratin

109
Q

present in hair, horn, and nails having high sulfur content

A

hard keratin

110
Q

abnormalities in keratin structure will cause loss of skin integrity and result in diseases like

A

epidermolysis bullosa

111
Q

first protein to be sequenced

A

insulin

112
Q

who sequenced insulin in 1955?

A

Sanger

113
Q

the purity of protein thus isolated is studied using

A

electrophoresis

114
Q

molecular weight can be determined by what process

A

mass spectroscopy

115
Q

steps for determining primary structure is first ascertained by treating them with what

A

dansyl chloride

116
Q

combines with N-terminal acid and the tagged polypeptide chain are subjected to what process by boiling with 6 N HCl at 110 degrees celsius

A

complete hydrolysis

117
Q

can indicate the number of polypeptide chains in determining the primary structure

A

dansyl amino acids

118
Q

originally, sanger used this for identification of N-terminal amino acid

A

flurodinitrobenzene (Sanger’s reagent)

119
Q

may be identified by carboxypeptidase A and B

A

C-terminal amino acid

120
Q

enyzmes that specifically hydrolyze and release the C-terminal amino acid from the polypeptide chain

A

carboxypeptidase A and B

121
Q

enzyme that will not act if C terminal is Arginine, Proline, or Lysine

A

Carboxypeptidase A

122
Q

will only act if the penultimate residue is proline

A

carboxypeptidase b

123
Q

purified individual polypeptide chains are then sequenced using what technique

A

Edman’s degradation technique

124
Q

Edman’s reagent is called

A

phenly isothiocynate

125
Q

forms a covalent bond to the N-terminal amino acid of any peptide chain, then reacts with second amino acid (now the alpha amino group)

useful in sequencing first 10-30 amino acids

A

Edman’s reagent

126
Q

hydrolyzes peptide bonds formed by alpha carboxyl group of Lysine and Arginine

A

Trypsin

127
Q

preferentially acts on peptide bonds formed by carboxyl group of amino acids Phe, Tyr, Trp, or Leu

A

Chymotrypsin

128
Q

attacks C-side of methionine residue and breaks the peptide bond (CNBr)

A

cyanogen bromide

129
Q

position of what bond can be determined by cleaving the native protein sample to get fragments with intact S-S bonds.

A

disulfide bonds

130
Q

helping the amino acid sequencing by having a rough sequencing of protein done by Edman’s method and then small length oligonucleotide primers are made

A

DNA sequencing

131
Q

after DNA sequencing, this process is done to amplify the appropriate gene

A

polyamerase chain reaction (PCR)

132
Q

artificially synthesized to get pure preparations for medical or diagnostic purpose e.g. HIV antibody in the blood

A

peptides

133
Q

introduced the solid phase peptide synthesis

A

Bruce Merrifield

134
Q

first major protein chemically synthesized

A

insulin

135
Q

shape of insulin

A

globular

136
Q

shape of albumin

A

oval

137
Q

purification of enzymes and other proteins usually start by what process

A

precipitating

138
Q

what groups of proteins (-NH2, COOH, OH) tend to attract water molecules around them to produce a shell of hydration

A

water

139
Q

procedures of protein precipitation that happens when a neutral salt, such as ammonium sulfate or sodium sulfate is added to a protein solution

A

salting out

140
Q

as a general rule, the higher the mol weight of a protein, the ___ the salt required for precipitation

A

lesser

141
Q

thus, globulins need more/less salt than albumin

A

less

142
Q

proteins are the least soluble at what pH

A

isoelectric pH

143
Q

forms a flocculent precipitate at 4.6 pH (its isoelectric pH) and redissolves in highly acidic or alkaline solutions

A

Casein

144
Q

what part of peptide are utilized for peptide bond formation, hence are not ionizable

A

alpha amino group
carboxyl group

145
Q

at the isoelectic point, the number of anions and cations on the protein molecule will be equal and and the net charge is ____

A

zero

146
Q

what structure is not altered during denaturation

A

primary structure

147
Q

sometimes used as an antidote for mercury poisoning

A

raw egg

148
Q

classification of proteins (7)

A

catalytic
structural
contractile
transport
regulatory proteins/hormones
genetic proteins
protective proteins

149
Q

when heated at isoelectric point, some proteins will denature irreversibly to produce thick floating conglomerates called

A

coagulum

150
Q

only contain amino acids

A

simple proteins

151
Q

soluble in water, and coagulated by heat. Has a molecular weight of 69,000, present in milk and egg

A

albumin

152
Q

insoluble in pure water, but soluble in dilute salt solutions, coagualted by heat, present in legumin of peas

A

globulin

153
Q

soluble in water, dilute acids but not coagulated by heating

contain a large number of arginine and lysine residues

A

protamines

154
Q

soluble in 70-80 alcohol, but insoluble in pure water. rich in proline but lack lysine (ex. corn, wheat, barley)

A

prolamins

155
Q

precipitated by 30-60 ammonium sulfate

have high affinity to sugar groups

PHA from red kidney bean that agglutinates RBCs and WBCs

A

Lectins

156
Q

insoluble in water, salt soltions, and organic solvents and soluble only in hot strong acids

form supporting tissues (collagen of bones, cartilage and tendon, keratin, horn, nail and hoof)

A

scleroproteins

157
Q

combinations of proteins with a non-protein part

A

conjugated proteins

158
Q

proteins combined with carbohydrates

A

glycoproteins

159
Q

hydroxyl groups of serine or threonine and amide groups of asparagine and glutamine form linkages with what residues

A

carbohydrates

160
Q

example of glycoproteins

A

serum proteins
blood group antigens

161
Q

glycoproteins when carbohydrate content is >10% is called

A

mucoproteins
proteoglycans

162
Q

proteins loosely combined with lipid components (occurs in blood and cell membranes)

A

lipoproteins

163
Q

proteins attached to nucleic acid (e.g. histones)

A

nucleoproteins

164
Q

DNA is positive/negatively charged that combines with Histones that is positive/negatively charged

A

DNA -
histones +

165
Q

proteins with colored prosthetic groups

A

chromoproteeins

166
Q

red colored prosthetic group

A

heme (hemoglobin)

167
Q

yellow colored prosthetic group

A

riboflavin (flavoproteins)

168
Q

purple colored prosthetic group

A

vitamin a (visual protein)

169
Q

proteins that contain phosphorus

A

phosphoproteins

170
Q

contain metal ions (ex. hemoglobin - iron, cytochrome - iron, tyrosinanse copper)

A

metalloproteins

171
Q

proteins to smallest unit

A

protein > peptones > peptides > amino acid

172
Q

proteins that are spherical or globular or oval in shape, easily soluble

A

globular proteins

173
Q

proteins where its molecules are elongated or needle shaped

solubility is minimum, resist digestion (ex. collagen, elastin, keratin)

A

fibrous proteins

174
Q

proteins that are complete, first class

contain all the essential amino acids

A

nutritionally rich proteins

175
Q

lack one essential amino acid, cannot promote body growth in children but sustain the body weight in adults

A

incomplete proteins

176
Q

lack in many essential amino acids and a diet based on this proteins will not sustain the original body weight

A

poor proteins

177
Q

when 10 or less number of amino acids are joined together it is called an

A

oligopeptide

178
Q

biologically important peptides (4)

A

thyrotropin releasing hormone (TRH)
glutathione
oxytocin and vasopressin (AD)
angiotensin I

179
Q

tripeptide with sequqnce of Glu-His-Pro but Glu and Pro are modified

A

thyrotropin releasing hormone (TRH)

180
Q

tripeptide, it is a gamma glutamyl cysteinyl glycine that evolved in erythrocyte membrane integrity and is important in keeping enzymes in active state

A

Glutathione

181
Q

nanopeptides, with 9 amino acids, secreted by posterior pituitary

A

oxytocin
vasopressin

182
Q

has 10 amino acids, pressor agents and elevate blood pressure

A

angiotensin I

183
Q

how many amino acids does angiotensin II have

A

8 amino caids

184
Q

procedure wherein the protein is digested by boiling with conc. sulfuric acid in presence of copper sulfate and sodium sulfate

A

Kjeldahl’s procedure

185
Q

on average, proteins contain what percent of nitrogen

A

16%

186
Q

most accurate and precise method of standardizing a particular protein

A

Kjeldahl’s procedure

187
Q

in this method, cupric ions with peptide bonds of proteis in alkaline medium produce a pink or violet color

intensity is proportional to the number of peptide bonds

A

Biuret Method

188
Q

based on the reduction of Folin-Ciocalteau phenol reagent by the tyrosine and tryptophan residue of protein

A

Lowry’s Method

189
Q

process wherein protein will absorb UV at 280 nm. This is due to the Tyr and Trp residues to quantify the absorbance of test solution with a known standar

A

Spectrophotometric Estimation

190
Q

detection of light scattered by turbid particles in solution

A

Nephelometry

191
Q

emergent light is proportional to the turbidity of the solution

T or F

A

T

192
Q

like nephelometry, this test utilize emergent light but is comparatively cheaper and at a different angle (180)

A

Turbidimetry

193
Q

proteins of nanogram and picogram quantities are to be estimated using this test

A

ELISA (enzyme-linked immunosorbent assay) test

194
Q

study of entire galaxy of proteins produced by a cell under different conditions

A

proteomics