Proteins I Flashcards
(118 cards)
1
Q
______ flavors can arise in proteinaceous systems due to low molecular weight ________________
A
Bitter
hydrophobic peptides
2
Q
Aromatic amino acids are largely (hydrophilic/hydrophobic)
A
hydrophobic
3
Q
What does the following sequence favour?
-P-N-P-P-N-N-P-
A
a-helix formation
4
Q
Proline and hydroxyproline are found extensively in __________ proteins
A
structural
5
Q
________ can serve as an attack point for reducing sugars
A
Amides
6
Q
The hydrophobicity of ________ AA increases as their chain lengthens
A
aliphatic
7
Q
The amino acids linked by peptide bonds represent the _______ level of structure of proteins
A
primary
8
Q
_______ is 50% ionized at pH 10.5
A
Lysine
9
Q
Glycine, Alanine, Valine, Leucine, and Isoleucine are _______ AA.
A
aliphatic
10
Q
______________ AA are readily hydrolyzed to their corresponding acids under conditions of heat and/or acidic conditions
A
Carboxylic
11
Q
OH-group on hydroxyl AA serve as a _________ bonding site and is a generally reactive moiety.
A
hydrogen
12
Q
____________ AA are found extensively in structural proteins
A
Imino acids
13
Q
The D configuration has an OH group on the _______
A
right
14
Q
Gamma-COOH group of ___________ are 50% ionized at pH 4.2
A
glutamic acids
15
Q
Quaternary structures do not have ___________, unlike tertiary structure
A
NO covalent bonds (disulfide crosslinks)
16
Q
What are nonpolar AA?
A
Glycine, Alanine, Valine, Leucine, Isoleucine, Methionine, Phenylalanine or Tryptophan
17
Q
Serine, Threonine, and Tyrosine are __________ AA.
A
hydroxyl
18
Q
A protein’s lowest point of solubility is at its ____________
A
isoelectric point
19
Q
___ separate macromolecules, of which __ are identical, are intertwined to form a suprahelix
A
3 2
20
Q
_______ aromatic AA is reactive due to its OH group; forms _____ linkages with phosphate
A
Tyrosine ester
21
Q
At low pH, the amino acid is _______
A
protonated (NH3+)
22
Q
The ____________ AA provide flavor due to their breakdown when being cooked, mainly due to the release of ______
A
sulfur-containing H2S
23
Q
_______ speed up the flavor development in cheese
A
Lipases
24
Q
The R group in Histidine is the _________ group
A
imidazole
25
What determines whether a helical structure forms?
AA composition
26
The ability to leaven dough is specifically due to \_\_\_\_\_\_\_\_\_\_
Gluten
27
The peptide bond is an ______ bond
amide
28
Surimi makes use of __________ to make analogs of crab meat and scallops
pollock
29
Monosodium glutamate is the _____________ salt of glutamic acid
monosodium
30
The _______ amino group is the most reactive amino group in Lysine.
epsilon
31
Synthetic production of amino acids generally leads to _________ mixtures of D and L isomers
racemic
32
In carboxylic AA, at pH 7 and above, most of the free carboxyl groups would be _________ charged.
negatively
33
Why aren't proline and hydroxyproline considered to be amino acids?
- They do not contain a true amino group (NH2) - Instead they contain an imino group (NH)
34
\_\_\_\_\_\_\_\_ readily undergoes rapid reaction with reducing sugars (Maillard reaction), which reduces the availability of this essential amino acid
Lysine
35
What structure does the following sequence favour?
-N-P-N-P-N-P-N-
B-sheet formation
36
Due to the ____________ form of AA and \_\_\_\_\_\_\_\_\_\_, protein polymers tend to twist upon itself
L-chiral steric hindrance
37
What are exogenous enzymes supplied by?
Microorgniams contaminating food
38
Amino acids can act as acids or bases and are said to be \_\_\_\_\_\_\_\_\_\_
amphoteric
39
The ___ structure wants to reduce its free energy
3rd
40
\_\_\_\_\_\_\_\_\_\_ are mirror images of a compound, which are not superimposable. ________ are an example
Enantiomers Amino acids
41
For all amino acids (except \_\_\_\_\_\_\_), the alpha-carbon is an asymmetric carbon
Glycine
42
The __________ group of cysteine is very basic, and ionized at pH 8.2
sulfhydral (-SH)
43
Meat contains an appreciable amount of \_\_\_\_\_\_\_\_\_\_\_, which provide flavor as well as being a source of ____________ products
free amino acids Maillard reaction
44
\_\_\_\_\_\_\_ is considered to be somewhat basic, and is capable of ionizing beyond pH 10
Tryptophan
45
\_\_\_\_\_\_\_ are used to tenderize meat.
Proteases
46
Proteins that have a significant amount of _______ and _______ tend to have high isoelectric points
lysines arginines
47
All proteins are synthesized from __ amino acids
L
48
Proteins are composed of ___ amino acids
20
49
\_\_\_\_\_\_\_\_\_ AA are relatively unreactive
aliphatic
50
The L configuration has an OH group on the \_\_\_\_\_\_\_
left
51
Disrupted _______ is extensively used in the food industry as a gelling agent
collagen
52
When an asymmetric carbon is present, molecules can rotate ___________ light in _______ directions
plane-polarized opposite
53
The suprahelix is held together by _______ bonds supplied by \_\_\_\_\_\_\_\_
hydrogen glycine
54
Lysine contains ___ amino groups
2
55
Lysine, Histidine, and Arginine are _______ AA.
basic
56
The side chains of the amides of _____________ and _____________ play a role in non-enzymatic browning reactions
aspartic acid glutamic acid
57
\_\_\_\_\_\_\_\_\_\_\_\_\_ are used to make meaty flavours
Protein hydrolysates
58
A very low pH is needed to suppress the _____ charges on the _____ side chains (i.e. to convert _____ to \_\_\_\_)
negative acidic COO- to COOH
59
\_\_\_\_\_\_\_\_\_\_\_\_\_ and _____________ do not contribute to a-helix formation
Proline hydroxyproline
60
A very high pH is needed to suppress the _____ charges on the _____ side chains (i.e. to convert _____ to \_\_\_\_)
positive basic NH3+ to NH2
61
\_\_\_\_\_\_\_ is used to remove headspace oxygen from food packages
Glucose oxidase
62
The _______________ of proteins is important in stabilizing protein conformation through \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
charge distribution electrostatic force
63
The _____ are more polar than the acid forms, and hence make proteins (more/less) water-soluble
amides more
64
The breakdown products of proteins , ________ and \_\_\_\_\_\_\_, are major contributors to flavor
amino acids peptides
65
\_\_\_\_\_\_\_\_\_\_ is a breakdown product of proteins that contributes to flavor in Chinese cuisine
MSG
66
\_\_ amino acids cannot be used by the body for protein synthesis
D
67
Amino acids decompose at relatively ___ temperatures due to their attributes as a \_\_\_\_\_
high salt
68
In a diester linkage, one ________ group is linked to two ________ AA via ester linkages
phosphate hydroxyl
69
Sugars and carbohydrate are often attached to the amide group of asparagine by an \_\_\_-glycosidic linkage
N
70
What is autolytically?
Using endogenous enzymes
71
Soy sauce is a _____________ produced by the fermentation of soybeans
protein hydrolysate
72
The quaternary structure of proteins represents ___ or more tertiary globular proteins associating as a group to form \_\_\_\_\_\_\_, \_\_\_\_\_\_, or\_\_\_\_\_\_\_\_
2 dimers, tetramers, or octamers
73
When _________________ AA are incorporated into a protein side chain, they interrupt the natural tendency to form an _______ since they cannot form intramolecular ________ bonds
imino a-helix hydrogen
74
\_\_\_\_\_\_\_\_ is weakly basic; ionized at pH 6
Histidine
75
\_\_\_\_\_\_\_ is a protein with elastic properties not found in other grains
Gluten
76
The peptide bond has a ____________ character
partial double bond
77
\_\_\_\_\_\_\_\_\_ AA play an important role in stabilizing protein conformation through hydrophobic interactions
Aromatic
78
What is attached to the alpha carbon in an amino acid?
- NH2 - COOH - R-group
79
Amino acids have a crystalline structure, and are soluble in water since they have the attributes of a \_\_\_\_\_\_\_
salt
80
The a-helix is stabilized by _______ bonding due to the repetitive proximity of the peptide ___________ (electron-rich) and the _________ from the nitrogen ___ residues away
hydrogen carbonyl oxygen hydrogen 4
81
Proline and hydroxyproline are _______ acids
imino
82
\_\_\_\_\_\_\_\_ are usually 5-15 AA in length
B-strands
83
\_\_\_\_\_ has been linked to Chinese Restaurant Syndrome
MSG
84
Carbohydrates are often attached to the OH group of _________ or _________ by an \_\_-glycosidic bond
serine threonine O
85
When the overall charge on the protein averages out to neutral, the protein is said to be at its \_\_\_\_\_\_\_\_\_\_\_\_
isoelectric point
86
The suprahelix is found in \_\_\_\_\_\_\_\_\_
collagen
87
\_\_\_\_\_\_\_\_\_ AA are very reactive and play an important role in protein structure
Carboxylic
88
At its isoelectric point, the amino acid is a \_\_\_\_\_\_\_\_\_\_\_
zwitterion
89
\_\_\_\_\_\_\_ proteins can form a curd
Milk and soybean
90
\_\_\_\_\_\_\_\_ contains a very basic guanidino group, which has a pKa of 12.5
Arginine
91
The structure of an enantiomer is \_\_\_\_\_\_\_
tetrahedral
92
Phenylalanine, Tyrosine, and Tryptophan are _______ AA.
aromatic
93
In a peptide bond, the ________ is linked to the \_\_\_\_\_\_\_\_\_\_
a-amino group a-carboxyl group
94
Does glutamic acid or glutamine dissolve better in water?
Glutamine
95
Collagen is a major structural animal protein composed of large amounts of _______ and \_\_\_\_\_\_\_
glycine proline
96
The polypeptide chain starts at the \_\_-terminus with the ____ group, and ends at the \_\_\_-terminus with the ____ group
N amino C carboxyl
97
The C-CO-NH-C unit is planar with the ___________ and ___________ of the peptide bond always trans to each other
carboxyl oxygen amino hydrogen
98
Aspartic and glutamic acids are found in nature as their corresponding \_\_\_\_\_\_\_: ____________ and \_\_\_\_\_\_\_\_\_\_\_\_
amides asparagine glutamine
99
Proteins that contain significant amounts of aspartic and glutamic acid tend to have _____ isoelectric points.
low
100
Rotation of the _________ is restricted to 6o
peptide bond
101
As the pH of an amino acid is increased, ___ protons are stripped away
Two
102
\_\_\_\_\_\_\_\_ is very reactive and can undergo oxidation/reduction reactions to form the _____ cystine
Cysteine
dimer
103
The major feature of ________ AA is their ability to form an ester linkage with a phosphate group
hydroxyl
104
\_\_\_\_\_\_\_\_ linkages play an important role in the 3D structure of a protein, and make it less susceptible to denaturation
Diester
105
\_\_\_\_\_\_\_\_\_\_ is a synonym for optical isomer
Enantiomers
106
AA are generally considered to be precursors of _____________ odors and flavors in meat and fish
putrefactive
107
Putrefactive odors and flavors are due to compounds produced by the _____________________________ by \_\_\_\_\_\_\_\_\_
enzymatic deamination or decarboxylation of free AA microbial enzymes
108
Meat analogs from soy protein via ___________ using __________ technology
texturization extrusion
109
B-carboxyl group of __________ are 50% ionized at pH 3.8
aspartic acids
110
What is the issue with racemic mixtures?
Only half have AA activity
111
Cysteine, Cystine, and Methionine are _______ AA.
sulfur-containing
112
If a _____ forms between ___ cysteine residues, it forms a \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
dimer 2 disulfide crosslink
113
\_\_ AA are considered essential
9
114
Each turn of the a-helix involves ___ AA residues
3.6
115
\_\_\_\_\_\_\_ are used to manufacture corn syrups/sugars
Amylases
116
What are the 5 types of interactions/bonds found in the tertiary structure of proteins?
- Hydrophobic interactions - Electrostatic interactions - Hydrogen bonding - Disulfide crosslinks - Van der Waals interactions
117
\_\_\_\_\_\_\_ amino acids are responsible for UV absorbance of most proteins at 280
Aromatic
118
The basic subunit for the suprahelix is \_\_\_\_\_\_\_\_\_\_\_
tropocollagen
