Chapter - 5
Protein Chemistry, Properties, and Analysis Methods
Protein Chemistry, Properties, and Analysis
Methods
1.
Proteins are high molecular weight polymers of a group of low molecular weight
monomers called:
A) Lipids
B) Carbohydrates
C) Amino acids
D) Nucleoproteins
2.
What is intimately associated with cell division and heredity, found in the
cell nucleus?
A) Enzymes
B) Amino acids
C) Lipids
D) Nucleoproteins
3.
Enzymes primarily serve what function in the cell cytoplasm?
A) Provide structure
B) Catalyze chemical changes
C) Store energy
D) Transport oxygen
4.
Excess proteins in animals can serve as a source of:
A) Connective tissue
B) Simple diffusible nutrients
C) Energy and fat
D) Hormones
5.
The most abundant substances in cell protoplasm are:
A) Carbohydrates
B) Lipids
C) Amino acids D) Proteins
6.
How many amino acids have been isolated from the proteins of all major classes
of living organisms, common to all?
A) More than 80
B) 9
C) 18
D) 20
7.
Amino acids that cannot be synthesized from other substances by the body cells
are called:
A) Nonessential amino acids
B) Non-nitrogenous amino acids
C) Essential amino acids
D) Alpha amino acids
8.
Which of the following is listed as an essential amino acid?
A) Glycine
B) Alanine
C) Phenylalanine
D) Proline
9.
Which of the following is listed as a nonessential amino acid?
A) Methionine
B) Tryptophan
C) Histidine
D) Glycine
10.
In the general formula for a protein chain, what does 'R' represent?
A) The peptide linkage
B) The free terminal amino group
C) The distinctive aromatic or aliphatic
radical of any of the 18 amino acids
D) The carboxyl group
11.
Amino acids with side chains containing basic groups include:
A) Serine, Threonine
B) Aspartic acid, Glutamic acid
C) Arginine, Lysine, Histidine
D) Glycine, Alanine
12.
The number of amino acids absorbed from the intestine into the portal blood
following digestion of a normal diet is approximately:
A) 18
B) 10
C) 20
D) 51
13.
Long chains of amino acids linked by the peptide bond are called:
A) Monopeptides
B) Dipeptides
C) Polypeptides
D) Simple globular proteins
14.
The simplest combination of amino acids that contains a peptide linkage is
called a:
A) Polypeptide
B) Tripeptide
C) Dipeptide
D) Tetrapeptide
15.
What is the number and order of amino acids in the polypeptide chains referred
to as?
A) Secondary structure
B) Quaternary structure
C) Tertiary structure
D) Primary structure
16.
The folding of polypeptide chains into a specific coiled structure held
together by disulfide and hydrogen bonds is the definition of which protein structure?
A) Primary structure
B) Secondary structure
C) Tertiary structure
D) Quaternary structure
17.
What are the three forms in which the polypeptide backbone exists in different
sections of a protein?
A) Fibrous protein, Globular protein,
Conjugated protein
B) alpha-helix, \beta-pleated sheet, Random
coil
C) Monomeric, Dimeric, Tetrameric
D) Primary, Secondary, Tertiary
18.
The arrangement and interrelationship of the twisted chains of protein into
specific layers, crystals or fibers is called the:
A) Primary structure
B) Secondary structure
C) Tertiary structure
D) Quaternary structure
19.
Quaternary structure is displayed when
several monomeric units combine, where these subunits are held together
primarily by:
A) Peptide bonds
B) Strong covalent bonds
C) Non-covalent bonds such as hydrogen and
ionic bonds
D) Ether linkages
20.
In the structure of collagen, what residue is found nearly every third position
because it is the only amino acid that can fit into the triple stranded helix?
A) Proline
B) Hydroxyproline
C) Glycine
D) Lysine
21.
Keratins, collagen, and elastin are examples of which type of protein?
A) Globular proteins
B) Conjugated globular proteins
C) Simple globular proteins
D) Fibrous proteins
22.
Fibrous proteins are generally known to be insoluble in:
A) Distilled water
B) Dil. salt solution
C) Organic solvents
D) All common solvents such as water, dil.
salt soln., dil. acids, alkalies and organic solvents
23.
Which simple globular protein is soluble in distilled water?
A) Protamines
B) Albumin
C) Histones
D) Globulins
24.
Globulins are classified as:
A) Water soluble simple globular proteins
B) Water insoluble globular proteins
C) Conjugated globular proteins
D) Fibrous proteins
25.
Proteins combined with pigments are called:
A) Glycoproteins
B) Lipoproteins
C) Chromoproteins
D) Nucleoproteins
26.
Mucin (in saliva) is an example of a conjugated globular protein combined with:
A) Lipids
B) Nucleic acid
C) Carbohydrates
D) Phosphoric acid
27.
Casein of milk is an example of which type of conjugated protein?
A) Lipoprotein
B) Chromoprotein
C) Phosphoprotein
D) Metalloprotein
28.
Denaturation of a protein is said to occur when the protein undergoes changes in:
A) Molecular weight only
B) Composition only
C) Structure or composition
D) Primary structure only
29.
Denaturation primarily results in the unfolding of the protein molecule due to
the destruction of:
A) Peptide bonds
B) Salt bridges by thermal agitation
C) Hydrogen bonds
D) Disulfide linkages
30.
Which mineral acid causes denaturation by destroying salt bridges by altering
the ionization of carboxyl and amino groups?
A) Nitric acid
B) Sulfosalicylic acid
C) Acetic acid
D) Citric acid
31.
Mineral alkalies, such as sodium hydroxide, denature proteins by:
A) Thermal agitation
B) Oxidative decomposition
C) Cleavage of hydrogen bonds
D) Splitting peptide bonds
32.
Neutral chemical agents, such as urea, cause protein denaturation by:
A) Splitting salt bridges
B) Mechanical deformation
C) Cleavage of hydrogen bonds
D) Splitting peptide bonds adjacent to
aromatic rings
33.
Amino acids react with ninhydrin to form a blue complex that maximally absorbs
light at what wavelength?
A) 640 nm
B) 570 nm
C) 520 nm
D) 603 nm
34.
The Biuret reaction tests for the presence of:
A) Aromatic rings
B) Alpha amino acids
C) Peptide linkages
D) Sulfhydryl groups
35.
The Biuret reaction is dependent upon the formation of a complex involving:
A) Silver
B) Copper
C) Iron
D) Zinc
36.
Albumin reacts specifically with Bromcresol green (BCG) at pH 4.1 to form what
colored complex?
A) Purple
B) Yellow
C) Greenish-blue
D) Red
37.
What is the process of movement of proteins in an electrical field called?
A) Chromatography
B) Nephelometry
C) Turbidimetry
D) Electrophoresis
38.
What is the isoelectric pH (pI) of a protein?
A) The pH at which it carries maximum
positive charge
B) The pH at which it is neutral and does
not carry any charge
C) The pH at which it binds lipids
D) The pH at which it precipitates easily
39.
What is the first step in the general metabolism of amino acids, where the
amino group is transferred from an amino acid to a keto acid?
A) Deamination
B) Decarboxylation
C) Transamination
D) Urea cycle
40.
Deamination, the removal of the amino group as NH3, results in the formation
of:
A) A tripeptide and urea
B) A ketoacid and ammonia
C) Glutamic acid
D) Pyruvic acid
41.
Oxidative deamination takes place mostly in which organs?
A) Spleen and pancreas
B) Heart and lungs
C) Liver and kidneys
D) Muscle and bone
42.
The major oxidative deamination reaction is catalyzed by which mitochondrial
enzyme?
A) Serum glutamate pyruvate transaminase
(SGPT)
B) Pepsin
C) Glutamate dehydrogenase (GLD)
D) Trypsin
43.
Ammonia derived from the deamination of alpha-amino acids is:
A) Non-toxic and excreted directly
B) Converted to urea in the kidneys
C) Toxic, and human tissues detoxify it by
converting it to glutamate for transport to the liver
D) Stored in muscle tissue
44.
The term "dynamic equilibrium" refers to the constant interchange
between:
A) Essential and nonessential amino acids
B) Plasma proteins and labile tissue
reserve
C) Serum albumin and globulin
D) Lipids and carbohydrates
45.
The most common metabolic disorder in amino acid metabolism, caused by a
deficiency of hepatic enzyme phenylalanine hydroxylase, is:
A) Albinism
B) Alkaptonuria
C) Phenylketonuria (PKU)
D) Wilson's disease
46.
What enzyme is defective in Phenylketonuria (PKU)?
A) Homogentisate oxidase
B) Tyrosinase
C) Phenylalanine hydroxylase
D) Glutamate dehydrogenase
47.
Which disorder is caused by the deficiency of homogentisate oxidase in tyrosine
metabolism, leading to urine that turns black or brown upon standing?
A) Phenylketonuria
B) Albinism
C) Alkaptonuria
D) Parkinson's disease
48.
The most common cause of Albinism is a defect in which enzyme?
A) Homogentisate oxidase
B) Tyrosinase
C) Phenylalanine hydroxylase
D) Ceruloplasmin
49.
Parkinson's disease is linked with decreased synthesis of which intermediate
compound formed in tyrosine metabolism?
A) Melanin
B) Homogentisate
C) Dopamine
D) Tyrosine
50.
What is the clinical condition in which increased amounts of proteins
(detectable by usual chemical methods) are present in urine?
A) Aminoaciduria
B) Microalbuminuria
C) Proteinuria
D) Hyperalbuminemia
51.
What is the approximate concentration of total protein in human plasma?
A) 3.3 - 4.8 g/dl
B) 10-40 mg/dl
C) 7.0-7.5 g/dl
D) Less than 1.0 g/dl
52.
Most plasma proteins are synthesized in the liver, with the exception of:
A) Albumin and globulins
B) Immunoglobulins and protein hormones
C) Fibrinogen and complement
D) Transferrin and ceruloplasmin
53.
Which transport protein binds thyroxin (T4) and triiodothyronine (T3)?
A) Retinal-Binding Protein (RBP)
B) Albumin
C) Prealbumin
D) Haptoglobin
54.
The most abundant protein in human plasma, representing 40-60% of the total
proteins, is:
A) Alpha-globulin
B) Fibrinogen
C) Albumin
D) Gamma-globulin
55.
What is the estimated half-life of albumin?
A) 12 hours
B) 90 minutes
C) 5 days
D) 15 to 19 days
56.
The most important biological functions of albumin include transport, storage
of ligands, serving as a source of endogenous amino acids, and maintaining the
plasma:
A) Hydrostatic pressure
B) Oncotic pressure
C) Coagulation balance
D) pH balance
57.
Which plasma glycoprotein binds extra-corpuscular hemoglobin in a tight
non-covalent complex?
A) Transferrin
B) Ceruloplasmin
C) Haptoglobin (Hp)
D) C-Reactive protein
58.
Transferrin, a 
1-globulin, plays a central role in the body's
metabolism of iron by:
A) Storing ferric ions
B) Transporting iron
C) Degrading extra-corpuscular hemoglobin
D) Inhibiting thrombin
59.
What protein carries 90% of the copper present in plasma and is an 
globulin?
A) Transferrin
B) Haptoglobin
C) Ceruloplasmin
D) Alpha2-Macroglobulin (AMG)
60.
Which disease is characterized by low levels of ceruloplasmin due to abnormal
metabolism of copper?
A) Nephrotic syndrome
B) Sickle cell anemia
C) Wilson's disease
D) Phenylketonuria
61.
C-Reactive Protein (CRP) is classified as an acute phase protein, synthesized
in the liver, and its normal concentration in serum is:
A) 10-40 mg/dl
B) Less than 800 micro-g/dl
C) 7.0-7.5 g/dl
D) 3.3-4.8 g/dl
62.
Which acute phase protein's concentration is markedly increased in nephrotic
syndrome because other proteins are lost in urine, while this large protein
tends to remain in the intravascular compartment?
A) Haptoglobin
B) Ceruloplasmin
C) Alpha2-Macroglobulin (AMG)
D) Albumin
63.
What is the method used for both manual and automated determinations of serum
(or plasma) total proteins?
A) Bromcresol Green (BCG) method
B) Rate Nephelometry
C) Biuret method
D) Turbidimetry
64.
The Biuret method is not suitable for body fluids containing low protein
concentrations, specifically less than:
A) 6-8 g/dl
B) 12 g/dl C) 2.0 g/dl D) 0.05 ml
65.
What method is typically used for the determination of serum (Plasma) albumin
in automation?
A) Biuret method
B) Bromcresol Green (BCG) method
C) Ninhydrin reaction
D) Sulfosalicylic acid turbidimetry
66.
In the BCG method for albumin determination, what color is the resulting
complex measured at 640 nm?
A) Blue-violet
B) Purple
C) Yellow
D) Greenish-blue
67.
Which method is used for the determination of total proteins in low protein
body fluids like urine and CSF?
A) Biuret method
B) Electrophoresis
C) Turbidimetry
D) HABA dye binding
68.
When serum proteins are subjected to electrophoresis using veronal buffer of pH
8.6, all proteins behave like anions and move towards the:
A) Anode
B) Cathode
C) Center line
D) Point of application
69.
In paper electrophoresis of serum proteins, which component is the fastest
moving?
A) Gamma-globulin
B) Beta-globulin
C) Alpha-1-globulin
D) Albumin
70.
In Rate Nephelometry, the intensity of
scattered light is measured at an angle of:
A) 90 degrees
B) 180 degrees
C) 70 degrees
D) 50 degrees
**CORRECT ANSWERS**
64. C
65. B
66. D
67. C
68. A
69. D
70. C
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