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Chem 193 Biochemistry C3 > Protein > Flashcards

Protein Flashcards

1
Q

Proteins account for more than __- of the
dry mass of most cells

A

50%

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2
Q

Selective acceleration of chemical reactions
Example: Digestive enzymes catalyze the hydrolysis
of bonds in food molecules.

A

Enzymatic proteins

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3
Q

Function: Protection against disease
Example: Antibodies inactivate and help destroy
viruses and bacteria

A

Defensive proteins

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4
Q

Function: Transport of substances
Examples: Hemoglobin, the iron-containing protein
of vertebrate blood, transports oxygen from the
lungs to other parts of the body. Other proteins
transport molecules across cell membranes.

A

Transport proteins

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5
Q

Function: Storage of amino acids Function: Transport of substances
Examples: Casein, the protein of milk, is the major
source of amino acids for baby mammals. Plants
have storage proteins in their seeds. Ovalbumin is
the protein of egg white, used as an amino acid
source for the developing embryo.

A

Storage proteins

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6
Q

Function: Response of cell to chemical stimuli
Example: Receptors built into the membrane
of a nerve cell detect signaling molecules released by
other nerve cells.

A

Receptor proteins

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7
Q

Function: Coordination of an organism’s activities
Example: Insulin, a hormone secreted by the
pancreas, causes other tissues to take up glucose,
thus regulating blood sugar concentration

A

Hormonal proteins

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8
Q

Function: Movement
Examples: proteins are responsible for the
undulations of cilia and flagella. Actin and myosin
proteins are responsible for the contraction of
muscles

A

Contractile and motor proteins

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9
Q

Function: Support
Examples: Keratin is the protein of hair, horns,
feathers, and other skin appendages. Insects and
spiders use silk fibers to make their cocoons and webs,
respectively. Collagen and elastin proteins provide a
fibrous framework in animal connective tissues.

A

Structural proteins

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10
Q

are polymers, that are composed
of a series of monomers linked together
by peptide bonds

A

Proteins

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11
Q

are unbranched polymers
built from the same set of 20 amino acids.

A

Polypeptides

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12
Q

differ in their properties
due to differing side chains, called R
groups

A

Amino acids

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13
Q

All amino acids are ______ due to the presence
of an asymmetric carbon atom in the molecule, except
for glycine.

A

optically active

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14
Q

All amino acids absorb in the ________,
except for tyrosine, tyrosine, tryptophan, and
phenylalanine, which absorbs at

A

far ultraviolet (<220 nm),
260-280 nm

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15
Q

naturally occuring, found in proteins, and the most
common and naturally-occurring amino acids

A

L-enantiomer

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16
Q

amino acid config found in bacterial cell walls and
certain antibiotics.

A

D-enantiomer

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17
Q

hybridization and geometrical shape of amino acid

A

sp3 and tetrahedral

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18
Q

Side chains that are mainly hydrocarbons
– Very unreactive and hydrophobic amino
acids

A

Nonpolar side chains

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19
Q

Subgroups of nonpolar side chain

A

Aliphatic Hydrocarbons
Aromatic Hydrocarbons

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20
Q

Nonpolar amino acid

A

alanine, valine, leucine, proline, methionine, tryptophan, glycine, isoleucine, and phenylalanine

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21
Q

Non chiral amino acid

A

glycine

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22
Q

nonpolar amino acid that can interact and
bind with metal ions. Often found in
metalloproteins

A

Methionine

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23
Q

Only imino acid

A

proline

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24
Q

Can be converted to serotonin

A

tryptophan

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25
The only nonpolar aromatic amino acids
Tryptophan Phenylalanine
26
Polar amino acids include
STCYNQ
27
Amino acids with -OH group
Threonine, tyrosine, serine
28
Converted to catecholamines – includes epinephrine (adrenaline) “fight or flight” hormone
Tyrosine
29
Amino acid with amide group
asparagine and glutamine
30
The only amino acid with sulfhydryl group
cysteine
31
Acidic amino acids
Glutamic and Aspartic acids
32
Basic amino acids
Histidine, lysine, arginine
33
Physiological pH of glutamate
7.4
34
Physiological pH of aspartate
7.4
35
Always negatively charge at Physiological pH
aspartate and glutamate
36
gain a proton at physiological pH ( pH=7.4)
Lysine, arginine, histidine
37
what group will be deprotonated first
carboxylic group
38
predominates at neutral pH
Zwitterion
39
are amphoteric and are often called ampholytes from “amphoteric electrolytes”
Zwitterion
40
When an amino acid is dissolved in water, it exists in solution as the dipolar ion or
Zwitterion
41
pH at which the positive equals the negative charge; net charge is or no ionizable side chain
isoelectric point
42
Isoelectric point equation
pI = pKa1 + pKa2 / 2
43
these amino acids can’t be synthesized in the body unlike the 11 other amino acids, so these amino acids should be derived or taken from the food
essential amino acids
44
what are the essential amino acids
PVT TIM HALL ( histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine)
45
Peptide bonds are generated via a ____________ synthesis reaction
dehydration
46
Amino acid is added to the __ terminus of the chain
C-terminus
47
3 peptide bond, 4 amino acids
Tetrapeptide
48
involved the removal of water molecule by forming amide bonds or peptide bonds.
Dehydration reaction
49
only happens when the desired pH is greater than the pKa values
deprotonation
50
A peptide with 9 amino acid residues and is the hormone of love.
Oxytocin
51
has 104 amino acid residues linked in a single chain
Human cytochrome c --
52
has 245 amino acid residues
Bovine chymotrypsinogen --
53
considered to be the largest protein which has nearly 27,000 amino acid residues; constituent of vertebral muscles
Titin --
54
results when a protein consists of multiple polypeptide chains
Quaternary structure
55
found in most proteins, consists of coils and folds in the polypeptide chain
secondary structure
56
unique sequence of amino acids
Primary structure
57
is determined by interactions among various side chains (R groups)
tertiary structure
58
an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin.
sickled cell
59
the amino acid substitution causes sickled cell
glutamic acid into valine
60
Structure of hemoglobin
quaternary
61
what secondary structure of hemoglobin is affected in sickled cell
beta subunit, exposed hydrophobic region
62
The coils and folds of secondary structure result from ______ between repeating constituents of the polypeptide backbone.
hydrogen bonds
63
Hydrogen bonding between _______________ in neighboring regions of the protein chain sometimes causes certain patterns of folding to occur.
amino groups and carboxyl groups
64
coil structures
alpha helix
65
folded structure
beta pleated sheet
66
examples of proteins with dominated alpha helix structure
elephant and horse hair myosin fibrin
67
examples of proteins with dominated beta pleated structure
silkworm gut and gelatine
68
types of beta pleated sheet
parallel and antiparallel
69
more stable type of beta pleated sheet
antiparallel
70
interactions between R groups in tertiary structure
hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions * Strong covalent bonds called disulfide bridges
71
type of tertiary structure
compact globular rodlike
72
Compact globular includes
ribonuclease, ovalbumin, serum ovalbumin, lysozyme, myoglobin
73
Rodlike/Fibrous includes
fibrinogen/collagen
74
* the first protein to which the tertiary structure was determined by X-ray crystallography * consists of 153 amino acids in a single chain with a prosthetic group, the heme group * a compact structure, with the interior atoms very close together --- responsible for the 3D shapes of proteins
Myoglobin
75
how many alpha helical structure does myoglobin have
8
76
In myoglobin, Two_________ residues are found in the interior; they are involved in interactions with the heme group and bound oxygen
polar histidine
77
how many heme group does myoglobin have
1
78
Myoglobin consists of a single polypeptide chain and so contains ____ heme group. On the other hand, hemoglobin consists of four polypeptide chains and so contains ____ heme groups.
1, 4
79
how many heme group does hemoglobin have
4
80
the structure that formed in a heme group
porphyrin ring
81
results when two or more polypeptide chains form one macromolecule
Quaternary structure
82
is a fibrous protein consisting of three polypeptides coiled like a rope
collagen
83
is a globular protein consisting of four polypeptides: two alpha and two beta chains
Hemoglobin
84
In quaternary structure, how many subunits does the ff have: Insulin Thrombin Hemoglobin Arginine decarboxylase
– 2 subunits – 3 subunits – 4 subunits – 5 subunits
85
Positive for proteins with two or more peptide bonds,
biuret test
86
positive and negative result in biuret test
pink-violet, blue
87
functional group detected in biuret test
peptide linkage
88
functional group detected in Ninhydrin test
free alpha-amino group
89
positive result in Ninhydrin test
blue-violet yellow in proline
90
Specific for the R groups of tyrosine and tryptophan.
Xanthoproteic test
91
positive result in Xanthoproteic test
yellow
92
functional group detected in xanthoproteic test
aromatic ring, except phenylalanine
93
why does phenylalanine do not give positive result in xanthoproteic test, even though it is an aromatic compound?
due to the high stability of its ring
94
what are four general aromatic amino acids
Tyrosine Tryptophan Phenylalanine Histidine
95
Histidine is an aromatic AA but is usually ignored due to its
basicity, positively charged side chain
96
Test specific for cysteine due to the sulfhydryl group
Sulfur testti
97
positive result in sulfur test
black precipitate due to the formation of PbS
98
test for phenolic amino acids (phenol group)
Millon's test
99
positive result for Millon's test
Red or pink ppt
100
Test for the presence of indole ring (Tryptophan)
ADAMKIEWICZ- HOPKINS TEST
101
positive result for Hopkins-cole test
purple ring appears between the two layers
102
reagents in Millons test
HgNO3 and HNO3
103
Test for the presence of guanido group (Arginine)
Sakaguchi test
104
positive result for sakaguchi test
Red complex
105
* on hydrolysis gives only amino acids * may be fibrous or globular
simple proteins
106
Simple proteins that are present in: - present in egg, milk and blood - present in combination with DNA or with heme to form hemoglobin of red blood cells - protein in cereals - structural proteins, not digested (keratin, collagen and elastin) - present in the DNA (forming chromatin)
*albumin and globulins * globins * gliadines * scleroproteins * histones
107
on hydrolysis, give protein part and non protein part (prosthetic group) such as metal ions, carbohydrates, lipids, phosphoric acid, nucleic acids and FAD
Conjugated Proteins
108
proteins conjugated with lipids; function to help lipids be transported in blood and help lipid soluble substances to pass through cell membranes
Lipoproteins -
108
- basic proteins (e.g. histones) conjugated with nucleic acid (DNA or RNA)
Nucleoproteins
108
- proteins conjugated with phosphate group. Phosphorus is attached to OH group of serine or threonine.
phosphoprotein
108
- proteins conjugated with metal like iron, copper, zinc,among others
Metalloproteins
108
- proteins conjugated with sugar (carbohydrate); e.g. – some hormones such as erythropoeitin, present in cell membrane structure, blood groups
Glycoproteins
109
- proteins conjugated with pigment e.g. Melanoprotein - proteins of hair or iris which contain melanin.
Chromoproteins
109
- proteins conjugated with Flavin Adenine Dinucleotide (FAD)
Flavoproteins
109
produced from hydrolysis of simple proteins and conjugated proteins
derived proteins
110
The loss of a protein’s native structure is called
denaturation
110
: from hydrolysis of collagen : from hydrolysis of albumin
Gelatin Peptone
110
– at either high or low extremes of pH, some of the charges on the protein are missing and so the electrostatic interactions that would normally stabilize the native, active form of the protein are drastically reduced leading to denaturation.
Extremes of pH
110
an increase in temperature favors vibrations within the molecule, and the energy of these vibrations can become great enough to disrupt the tertiary structure
heat
110
– these reagents form Hbonds with the protein that are stronger that those within the protein itself.
urea and guanidine hydrochloride
110
– this is frequently used to reduce disulfide bridges to two sulfhydryl groups.
Β-mercaptoethanol
111
111
111
111
112
112
112
112
112
112
Scientists use to determine a protein’s structure
X-ray crystallography
113
113
113
are protein molecules that assist the proper folding of other proteins * Diseases such as Alzheimer’s, Parkinson’s, and mad cow disease are associated with misfolded proteins
Chaperonins

Chem 193 Biochemistry C3 (4 decks)

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