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Chem 193 Biochemistry C3 > Protein > Flashcards

Protein Flashcards

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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
Q

The only nonpolar aromatic amino acids

A

Tryptophan
Phenylalanine

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26
Q

Polar amino acids include

A

STCYNQ

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27
Q

Amino acids with -OH group

A

Threonine, tyrosine, serine

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28
Q

Converted to catecholamines –
includes epinephrine (adrenaline)
“fight or flight” hormone

A

Tyrosine

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29
Q

Amino acid with amide group

A

asparagine and glutamine

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30
Q

The only amino acid with sulfhydryl group

A

cysteine

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31
Q

Acidic amino acids

A

Glutamic and Aspartic acids

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32
Q

Basic amino acids

A

Histidine, lysine, arginine

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33
Q

Physiological pH of glutamate

A

7.4

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34
Q

Physiological pH of aspartate

A

7.4

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35
Q

Always negatively charge at Physiological pH

A

aspartate and glutamate

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36
Q

gain a proton at physiological pH
( pH=7.4)

A

Lysine, arginine, histidine

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37
Q

what group will be deprotonated first

A

carboxylic group

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38
Q

predominates at
neutral pH

A

Zwitterion

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39
Q

are amphoteric
and are often called
ampholytes from
“amphoteric electrolytes”

A

Zwitterion

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40
Q

When an amino acid is
dissolved in water, it exists
in solution as the dipolar ion or

A

Zwitterion

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41
Q

pH at
which the positive equals
the negative charge; net
charge is or no
ionizable side chain

A

isoelectric point

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42
Q

Isoelectric point equation

A

pI = pKa1 + pKa2 / 2

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43
Q

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

A

essential amino acids

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44
Q

what are the essential amino acids

A

PVT TIM HALL ( histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine)

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45
Q

Peptide bonds are generated via a
____________ synthesis reaction

A

dehydration

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46
Q

Amino acid is added to the __ terminus of the chain

A

C-terminus

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47
Q

3 peptide bond, 4 amino acids

A

Tetrapeptide

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48
Q

involved the removal of water
molecule by forming amide bonds or peptide bonds.

A

Dehydration reaction

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49
Q

only happens when the desired pH is greater than the pKa values

A

deprotonation

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50
Q

A peptide with 9 amino acid
residues and is the hormone of
love.

A

Oxytocin

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51
Q

has 104 amino acid residues
linked in a single chain

A

Human cytochrome c –

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52
Q

has 245 amino acid
residues

A

Bovine chymotrypsinogen –

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53
Q

considered to be the largest protein which has
nearly 27,000 amino acid residues; constituent of
vertebral muscles

A

Titin –

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54
Q

results when a protein
consists of multiple polypeptide chains

A

Quaternary structure

55
Q

found in most proteins,
consists of coils and folds in the polypeptide
chain

A

secondary structure

56
Q

unique sequence of amino acids

A

Primary structure

57
Q

is determined by interactions
among various side chains (R groups)

A

tertiary structure

58
Q

an inherited blood
disorder, results from a single amino acid
substitution in the protein hemoglobin.

A

sickled cell

59
Q

the amino acid substitution causes sickled cell

A

glutamic acid into valine

60
Q

Structure of hemoglobin

A

quaternary

61
Q

what secondary structure of hemoglobin is affected in sickled cell

A

beta subunit, exposed hydrophobic region

62
Q

The coils and folds of secondary structure result from ______ between repeating constituents of the polypeptide backbone.

A

hydrogen bonds

63
Q

Hydrogen bonding between _______________ in neighboring regions of the protein chain sometimes causes certain patterns of folding to occur.

A

amino groups and carboxyl groups

64
Q

coil structures

A

alpha helix

65
Q

folded structure

A

beta pleated sheet

66
Q

examples of proteins with dominated alpha helix structure

A

elephant and horse hair
myosin
fibrin

67
Q

examples of proteins with dominated beta pleated structure

A

silkworm gut and gelatine

68
Q

types of beta pleated sheet

A

parallel and antiparallel

69
Q

more stable type of beta pleated sheet

A

antiparallel

70
Q

interactions between R groups in tertiary structure

A

hydrogen bonds, ionic bonds, hydrophobic
interactions, and van der Waals interactions
* Strong covalent bonds called disulfide bridges

71
Q

type of tertiary structure

A

compact globular
rodlike

72
Q

Compact globular includes

A

ribonuclease,
ovalbumin,
serum ovalbumin,
lysozyme, myoglobin

73
Q

Rodlike/Fibrous includes

A

fibrinogen/collagen

74
Q
  • 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
A

Myoglobin

75
Q

how many alpha helical structure does myoglobin have

A

8

76
Q

In myoglobin, Two_________ residues are found in the
interior; they are involved in interactions with
the heme group and bound oxygen

A

polar histidine

77
Q

how many heme group does myoglobin have

A

1

78
Q

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.

A

1, 4

79
Q

how many heme group does hemoglobin have

A

4

80
Q

the structure that formed in a heme group

A

porphyrin ring

81
Q

results when two
or more polypeptide chains form one
macromolecule

A

Quaternary structure

82
Q

is a fibrous protein consisting
of three polypeptides coiled like a rope

A

collagen

83
Q

is a globular protein
consisting of four polypeptides: two
alpha and two beta chains

A

Hemoglobin

84
Q

In quaternary structure, how many subunits does the ff have:

Insulin
Thrombin
Hemoglobin
Arginine decarboxylase

A

– 2 subunits
– 3 subunits
– 4 subunits
– 5 subunits

85
Q

Positive for proteins with two or more peptide
bonds,

A

biuret test

86
Q

positive and negative result in biuret test

A

pink-violet, blue

87
Q

functional group detected in biuret test

A

peptide linkage

88
Q

functional group detected in Ninhydrin test

A

free alpha-amino group

89
Q

positive result in Ninhydrin test

A

blue-violet
yellow in proline

90
Q

Specific for the R groups of tyrosine and
tryptophan.

A

Xanthoproteic test

91
Q

positive result in Xanthoproteic test

A

yellow

92
Q

functional group detected in xanthoproteic test

A

aromatic
ring, except phenylalanine

93
Q

why does phenylalanine do not give positive result in xanthoproteic test, even though it is an aromatic compound?

A

due to the high stability of its ring

94
Q

what are four general aromatic amino acids

A

Tyrosine
Tryptophan
Phenylalanine
Histidine

95
Q

Histidine is an aromatic AA but is usually ignored due to its

A

basicity, positively charged side chain

96
Q

Test specific for cysteine due to the sulfhydryl group

A

Sulfur testti

97
Q

positive result in sulfur test

A

black precipitate due to the formation of PbS

98
Q

test for phenolic amino acids (phenol group)

A

Millon’s test

99
Q

positive result for Millon’s test

A

Red or pink ppt

100
Q

Test for the presence of indole ring (Tryptophan)

A

ADAMKIEWICZ- HOPKINS TEST

101
Q

positive result for Hopkins-cole test

A

purple ring appears between the two layers

102
Q

reagents in Millons test

A

HgNO3 and HNO3

103
Q

Test for the presence of guanido group (Arginine)

A

Sakaguchi test

104
Q

positive result for sakaguchi test

A

Red complex

105
Q
  • on hydrolysis gives only amino acids
  • may be fibrous or globular
A

simple proteins

106
Q

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)

A

*albumin and globulins
* globins
* gliadines
* scleroproteins
* histones

107
Q

on hydrolysis, give protein part and non protein
part (prosthetic group) such as metal ions,
carbohydrates, lipids, phosphoric acid, nucleic
acids and FAD

A

Conjugated Proteins

108
Q

proteins conjugated with lipids;
function to help lipids be transported in blood
and help lipid soluble substances to pass
through cell membranes

A

Lipoproteins -

108
Q
  • basic proteins (e.g. histones)
    conjugated with nucleic acid (DNA
    or RNA)
A

Nucleoproteins

108
Q
  • proteins conjugated with
    phosphate group. Phosphorus is attached to OH
    group of serine or threonine.
A

phosphoprotein

108
Q
  • proteins conjugated with metal like
    iron, copper, zinc,among others
A

Metalloproteins

108
Q
  • proteins conjugated with sugar
    (carbohydrate); e.g. – some hormones such as
    erythropoeitin, present in cell membrane
    structure, blood groups
A

Glycoproteins

109
Q
  • proteins conjugated with
    pigment
    e.g. Melanoprotein - proteins of hair or iris which
    contain melanin.
A

Chromoproteins

109
Q
  • proteins conjugated with Flavin
    Adenine Dinucleotide (FAD)
A

Flavoproteins

109
Q

produced from hydrolysis of simple proteins and
conjugated proteins

A

derived proteins

110
Q

The loss of a protein’s native structure is called

A

denaturation

110
Q

: from hydrolysis of collagen
: from hydrolysis of albumin

A

Gelatin
Peptone

110
Q

– 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.

A

Extremes of pH

110
Q

an increase in
temperature favors
vibrations within the
molecule, and the
energy of these
vibrations can become
great enough to disrupt
the tertiary structure

A

heat

110
Q

– these reagents form Hbonds with the protein that are stronger
that those within the protein itself.

A

urea and guanidine
hydrochloride

110
Q

– this is frequently
used to reduce disulfide bridges to two
sulfhydryl groups.

A

Β-mercaptoethanol

111
Q
A
111
Q
A
111
Q
A
111
Q
A
112
Q
A
112
Q
A
112
Q
A
112
Q
A
112
Q
A
112
Q

Scientists use to
determine a protein’s structure

A

X-ray crystallography

113
Q
A
113
Q
A
113
Q

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

A

Chaperonins

Chem 193 Biochemistry C3 (4 decks)

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