Proteins Flashcards
1
Q
The word protein is derived from the Greek word
A
proteios
2
Q
The word protein is derived from the Greek word, “proteios” which means
A
primary
3
Q
are used for bodybuilding; ____ molecules carry out all the major structural and functional aspects of the body.
A
protein
4
Q
Abnormality in protein structure will lead to
A
molecular diseases
5
Q
Proteins contain what major elements (4)
A
carbon
hydrogen
oxygen
nitrogen
6
Q
minor constituents of protein
A
sulfur
phosphorus
7
Q
On average, the nitrogen content of ordinary proteins is __% by weight
A
16
8
Q
All proteins are polymers of
A
amino acids
9
Q
chain of amino acids bound to one another by peptide bonds
A
protein
10
Q
parts of an amino acid (4)
A
central carbon
carboxylic acid group
amino group
side chain
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
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
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
14
Q
provide essential amino acids that allows the body to produce proteins, hormones, and other important molecules
A
dietary proteins
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
16
Q
made by gastric chief cells, cleaves any available protein into oligopeptide chains
A
pepsin
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
18
Q
cells where dipeptides and tripeptides are converted into amino acids
A
intestinal cells
19
Q
all nine essential amino acids are provided by what food
A
animal-based protein
20
Q
provide high amount of some while low amounts of others are provided in these foods
A
plant foods
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
22
Q
synthesized by the polymerization of amino acids through peptide bonds
A
proteins
23
Q
two amino acids combined to form a what
A
dipeptide
24
Q
three amino acids form a what
A
tripeptide
25
four amino acids will form what
tetrapeptide
26
a few amino acids together will make a what
oligopeptide
27
combination of 10-50 amino acids forms an
polypeptide
28
long polypeptide chains containing more than 50 amino acids are called ___
proteins
29
different levels of structural organization of proteins
primary
secondary
tertiary
quaternary
30
means the order of amino acids in the polypeptide chain and the location of disulfide bonds, if any
what structure
primary
31
is the steric relationship of amino acids, close to each other
secondary structure
32
denotes the overall arrangement and inter-relationship of the various regions, or domains of a single polypeptide chain
tertiary structure
33
results when the proteins cosist of two or more polypeptide chains held together by non-covalent forces
quaternary structure
34
the primary structure is maintained by what bonds of the peptide linkages
covalent bonsd
35
partial double bond
peptide bond
36
C-N bond is 'trans' or 'cis'
trans
37
distance between peptide bonds
1.32A
38
angles of rotation of side chains of the peptide bonds are known as
Ramachandran angles
39
in a polypeptide chain, at one end there will be one free alpha amino group called
amino terminal (N-terminal) end
40
amino acid contributing the alpha-amino group is named as what amino acid
first amino acid
41
the other end of the poylpeptide chain where there is a free alpha carboxyl group
carboxy terminal end (c-terminal)
42
amino acid residues in polypeptides are named by changing the suffix "-ine" to what
-yl
43
branching points in the chains may be produced by interchain
disulphide bridges
44
bond between the disulphide bridges are what kind
covalent
45
the covalent disulphide bonds between different polypeptide chains in the same protein are called
interchain
46
covalent disulphide bonds between different polypeptide chains in portions of same polypeptide chain
intrachain
47
rarely, instead of the alpha COOH group, this part of the glutamic acid may enter into peptide formation
gamma carboxyl
48
is used to denote such peptide bond formed by carboxyl group, other than that present in alpha position
pseudopeptide
49
protein in circular form
gramicidin
50
has two polypeptide chains, a chain of glycine (21 amino acids) b chain of phenylalanine (30 amino acids)
insulin
51
how many interchain disulfide bonds are there in insulin
two
52
what cysteine in A chain and B chain are connected
7th and 19th
53
intrachain disulfide bond between chain a and b is located in what
chain a - 6th and 11th
54
beta cells of pancreas synthesize insulin as prohormone called
proinsulin
55
single polypeptide chain with 86 amino acids
proinsulin
56
biologically active insulin (2 chains) is formed by the removal of what portion of proisulin before release
central
57
a protein with a specific primary structure will automatically form what shape
three-dimensional
58
means the spacial relationship of every atom in a molecule
conformation
59
denotes the spatial relationship between particular atoms
configuration
60
denotes the configurational relationship between residues, which are about 3-4 amino acids apart in the linear sequence
secondary structure
61
secondary and tertiary levels of protein structure are preserved by ___
noncovalent forces or bonds
62
noncovalent forces/bonds in secondary and tertiary structure of proteins
hydrogen bonds
electrostatic bonds
hydrophobic interactions
van der Waals forces
63
most common and stable conformation for a polypeptide chain (secondary structure)
alpha helix
64
in proteins like ___ and ____, the alpha helix is abundant
hemoglobin
myoglobin
65
structure of alpha helix wherein he polypeptide bonds form the back-bone and side chains of amino acids extending outward
spiral structure
66
alpha structure is stabilized by what bonds between NH and C=O groups of the main chain
hydrogen bonds
67
alpha-helix is generally left/right handed
right
68
this configuration of alpha helix is rare, because amino acids found in proteins are of L-variety
left handed
69
the polypeptide chains in this is almost fully extended, the distance between adjacent amino acids is 3.5A
Beta-Pleated Sheet
70
stabilized by hydrogen bonds between NH and C=O groups of neighboring polypeptide segments
what secondary structure
beta-pleated sheet
71
major structural motif in proteins like silk fibroin, flavodoxin, and carbonic anhydrase
beta-pleated sheet
72
fibroin is parallel/anti-parallel/both?
anti-parallel
73
flavodoxin is parallel/anti-parallel/both?
parallel
74
carbonic anhydrase is parallel/anti-parallel/both?
both
75
may be formed in many proteins in beta-pleated sheet due to the abrupt U-turn folding of the chain
beta bends
76
what stabilizes beta bends in b-pleated sheet?
intrachain disulfide bridges
77
denotes three dimensional structure of the whole protein
tertiary structure
78
defines the steric relationship of amino acids which are far apart from each other in the linear sequence, but are close in three-dimensional
tetriary structure
79
aggregated polypeptides in a functional protein
quaternary structure
80
forces that keep quaternary structure (4)
hydrogen bonds
electrostatic bonds
hydrophobic bonds
van der Waals forces
81
depending on the number of polypeptide chain, the protein may be termed as
1- chain
2 chain
4 chhain
monomer
dimer
tetramer
82
each polypeptide chain is termed as a __
subunit, monomer
83
contain two copies of the same polypeptide chain
homodimer
84
contains two different types of polypeptides as a functional unit
heterodimer
85
creatine kinase (CK) is what
monomer/dimer/tetramer
dimer
86
lactate dehyrodgenase is what
monomer/dimer/tetramer
tetramer
87
structural conformation that provides and maintains the functional characteristics
three-dimensional
88
catalyses the reversible hydration of carbon dioxide
carbonic anhydrase
89
structural motif present in myoglobin
alpha helix and beta pleated sheet
90
structural motif present in collagen
triple helix
91
structural motif present in keratin
coiled coil
92
structural motif present in elastin
no specific motif
93
motif present in superoxide dimutase
antiparallel beta pleated sheet
94
transporter of oxygen that is a tetrameric protein, with each monomer having a heme unit
hemoglobin
95
binding of H+ and CO2 promotes the release of what in heme
O2
96
allosteric interaction that binds H+ and CO2 to heme to release oxygen
Bohr effect
97
most abundant protein in mammals and is the main fibrous component of skin, bone, tendon, cartilage, and teeth
collagen
98
forms a superhelical cable where 3 polypeptide chains are wound around itself
collagen
99
in collagen, every 3rd residue is what
glycine
100
replacement of central glycine in collagen can result to what
brittle bone disesase
101
the triple helix of ___ is stabilized by the steric repulsion of the rings of hydroxyproline and also by hydrogen bonds between them
collagen
102
in this deficiency, failure oh hydroxylation of proline/lysine lead to reduced hydrogen bonding and consequent weakness of collagen
vitamin C deficiency
103
in collagen, this is responsible for its tensile strength
quarter staggered triple helical structure
104
heat denatured collagen
gelatin
105
mammals contain what kind of keratin
alpha-keratin
106
classified into soft and hard depending on sulfur content
keratin
107
residues that are responsible for disulfide bridge formation which confers characteristic for each type of protein
cysteine
108
have low sulfur content, present in skin
soft keratin
109
present in hair, horn, and nails having high sulfur content
hard keratin
110
abnormalities in keratin structure will cause loss of skin integrity and result in diseases like
epidermolysis bullosa
111
first protein to be sequenced
insulin
112
who sequenced insulin in 1955?
Sanger
113
the purity of protein thus isolated is studied using
electrophoresis
114
molecular weight can be determined by what process
mass spectroscopy
115
steps for determining primary structure is first ascertained by treating them with what
dansyl chloride
116
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
complete hydrolysis
117
can indicate the number of polypeptide chains in determining the primary structure
dansyl amino acids
118
originally, sanger used this for identification of N-terminal amino acid
flurodinitrobenzene (Sanger's reagent)
119
may be identified by carboxypeptidase A and B
C-terminal amino acid
120
enyzmes that specifically hydrolyze and release the C-terminal amino acid from the polypeptide chain
carboxypeptidase A and B
121
enzyme that will not act if C terminal is Arginine, Proline, or Lysine
Carboxypeptidase A
122
will only act if the penultimate residue is proline
carboxypeptidase b
123
purified individual polypeptide chains are then sequenced using what technique
Edman's degradation technique
124
Edman's reagent is called
phenly isothiocynate
125
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
Edman's reagent
126
hydrolyzes peptide bonds formed by alpha carboxyl group of Lysine and Arginine
Trypsin
127
preferentially acts on peptide bonds formed by carboxyl group of amino acids Phe, Tyr, Trp, or Leu
Chymotrypsin
128
attacks C-side of methionine residue and breaks the peptide bond (CNBr)
cyanogen bromide
129
position of what bond can be determined by cleaving the native protein sample to get fragments with intact S-S bonds.
disulfide bonds
130
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
DNA sequencing
131
after DNA sequencing, this process is done to amplify the appropriate gene
polyamerase chain reaction (PCR)
132
artificially synthesized to get pure preparations for medical or diagnostic purpose e.g. HIV antibody in the blood
peptides
133
introduced the solid phase peptide synthesis
Bruce Merrifield
134
first major protein chemically synthesized
insulin
135
shape of insulin
globular
136
shape of albumin
oval
137
purification of enzymes and other proteins usually start by what process
precipitating
138
what groups of proteins (-NH2, COOH, OH) tend to attract water molecules around them to produce a shell of hydration
water
139
procedures of protein precipitation that happens when a neutral salt, such as ammonium sulfate or sodium sulfate is added to a protein solution
salting out
140
as a general rule, the higher the mol weight of a protein, the ___ the salt required for precipitation
lesser
141
thus, globulins need more/less salt than albumin
less
142
proteins are the least soluble at what pH
isoelectric pH
143
forms a flocculent precipitate at 4.6 pH (its isoelectric pH) and redissolves in highly acidic or alkaline solutions
Casein
144
what part of peptide are utilized for peptide bond formation, hence are not ionizable
alpha amino group
carboxyl group
145
at the isoelectic point, the number of anions and cations on the protein molecule will be equal and and the net charge is ____
zero
146
what structure is not altered during denaturation
primary structure
147
sometimes used as an antidote for mercury poisoning
raw egg
148
classification of proteins (7)
catalytic
structural
contractile
transport
regulatory proteins/hormones
genetic proteins
protective proteins
149
when heated at isoelectric point, some proteins will denature irreversibly to produce thick floating conglomerates called
coagulum
150
only contain amino acids
simple proteins
151
soluble in water, and coagulated by heat. Has a molecular weight of 69,000, present in milk and egg
albumin
152
insoluble in pure water, but soluble in dilute salt solutions, coagualted by heat, present in legumin of peas
globulin
153
soluble in water, dilute acids but not coagulated by heating
contain a large number of arginine and lysine residues
protamines
154
soluble in 70-80 alcohol, but insoluble in pure water. rich in proline but lack lysine (ex. corn, wheat, barley)
prolamins
155
precipitated by 30-60 ammonium sulfate
have high affinity to sugar groups
PHA from red kidney bean that agglutinates RBCs and WBCs
Lectins
156
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)
scleroproteins
157
combinations of proteins with a non-protein part
conjugated proteins
158
proteins combined with carbohydrates
glycoproteins
159
hydroxyl groups of serine or threonine and amide groups of asparagine and glutamine form linkages with what residues
carbohydrates
160
example of glycoproteins
serum proteins
blood group antigens
161
glycoproteins when carbohydrate content is >10% is called
mucoproteins
proteoglycans
162
proteins loosely combined with lipid components (occurs in blood and cell membranes)
lipoproteins
163
proteins attached to nucleic acid (e.g. histones)
nucleoproteins
164
DNA is positive/negatively charged that combines with Histones that is positive/negatively charged
DNA -
histones +
165
proteins with colored prosthetic groups
chromoproteeins
166
red colored prosthetic group
heme (hemoglobin)
167
yellow colored prosthetic group
riboflavin (flavoproteins)
168
purple colored prosthetic group
vitamin a (visual protein)
169
proteins that contain phosphorus
phosphoproteins
170
contain metal ions (ex. hemoglobin - iron, cytochrome - iron, tyrosinanse copper)
metalloproteins
171
proteins to smallest unit
protein > peptones > peptides > amino acid
172
proteins that are spherical or globular or oval in shape, easily soluble
globular proteins
173
proteins where its molecules are elongated or needle shaped
solubility is minimum, resist digestion (ex. collagen, elastin, keratin)
fibrous proteins
174
proteins that are complete, first class
contain all the essential amino acids
nutritionally rich proteins
175
lack one essential amino acid, cannot promote body growth in children but sustain the body weight in adults
incomplete proteins
176
lack in many essential amino acids and a diet based on this proteins will not sustain the original body weight
poor proteins
177
when 10 or less number of amino acids are joined together it is called an
oligopeptide
178
biologically important peptides (4)
thyrotropin releasing hormone (TRH)
glutathione
oxytocin and vasopressin (AD)
angiotensin I
179
tripeptide with sequqnce of Glu-His-Pro but Glu and Pro are modified
thyrotropin releasing hormone (TRH)
180
tripeptide, it is a gamma glutamyl cysteinyl glycine that evolved in erythrocyte membrane integrity and is important in keeping enzymes in active state
Glutathione
181
nanopeptides, with 9 amino acids, secreted by posterior pituitary
oxytocin
vasopressin
182
has 10 amino acids, pressor agents and elevate blood pressure
angiotensin I
183
how many amino acids does angiotensin II have
8 amino caids
184
procedure wherein the protein is digested by boiling with conc. sulfuric acid in presence of copper sulfate and sodium sulfate
Kjeldahl's procedure
185
on average, proteins contain what percent of nitrogen
16%
186
most accurate and precise method of standardizing a particular protein
Kjeldahl's procedure
187
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
Biuret Method
188
based on the reduction of Folin-Ciocalteau phenol reagent by the tyrosine and tryptophan residue of protein
Lowry's Method
189
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
Spectrophotometric Estimation
190
detection of light scattered by turbid particles in solution
Nephelometry
191
emergent light is proportional to the turbidity of the solution
T or F
T
192
like nephelometry, this test utilize emergent light but is comparatively cheaper and at a different angle (180)
Turbidimetry
193
proteins of nanogram and picogram quantities are to be estimated using this test
ELISA (enzyme-linked immunosorbent assay) test
194
study of entire galaxy of proteins produced by a cell under different conditions
proteomics
