1300487
Pregunta 1
Pregunta
An individual molecule of glycine possesses ________ carbon(s), and an individual molecule of alanine possesses _______ carbon (s).
Respuesta
-
2,2
-
1,2
-
2,1
-
2,3
-
3,2
Pregunta 2
Pregunta
A recent study found that polyQ aggregation can interfere with the clearance of misfiled proteins in the cytosol. PolyQ is a serial repeat of _____________ residues.
Respuesta
-
Arginine
-
Glycine
-
Glutamate
-
Ubiquitin
-
Glutamine
Pregunta 3
Pregunta
With the exception of glycine, all the standard proteinogenic amino acids __________
Respuesta
-
Contain an optically inactive alpha carbon
-
Do not exhibit chirality
-
Are found in biological systems in equal ratios of the two superimposable stereoisomeric conformations
-
All of the above are true
-
None of the above are true
Pregunta 4
Pregunta
_______________ is formed by post-translational modification of the collagen molecule.
Respuesta
-
Proline
-
Hydroxyproline
-
Pyrrolysine
-
Selenocysteine
-
Gamma-carboxyglutamate
Pregunta 5
Pregunta
Phosphates cannot normally be attached to ________________ .
Respuesta
-
Asparagine
-
Serine
-
Threonine
-
Phosphates cannot be attached to any of the above
-
Phosphates can be attached to all of the above
Pregunta 6
Pregunta
At neutral pH, the side chains of __________ are charged.
Respuesta
-
Lysine
-
Arginine
-
Aspartic acid
-
The side chains of all of the above are charged
-
The side chains of none of the above are charged
Pregunta 7
Pregunta
Which of the following bonds in a peptide exhibits the greater amount of free rotation?
Respuesta
-
The bond between the carbonyl carbon and the nitrogen of the peptide bond
-
The bond between the alpha carbon and the alpha-amino (the amino group attached to the central carbon of an amino acid)
Pregunta 8
Pregunta
A decapeptide (peptide composed of 10 amino acids) contains ______ peptide bonds. _____________ of these peptide bonds possess polarity and also partial double bond character.
Respuesta
-
Two, None
-
Nine, Nine
-
Ten, None
-
Eleven, Ten
-
Nine, None
Pregunta 9
Pregunta
A disulfide bond can be formed by the _________ of two _________
Respuesta
-
Reduction, selenocysteines
-
Oxidation, selenocysteines
-
Reduction, cystines
-
Oxidation, cystines
-
None of the above
Pregunta 10
Pregunta
Serotonin is synthesized from an amino acid precursor. This amino acid is ____________.
Respuesta
-
Tyrosine
-
Histidine
-
Cysteine
-
Tryptophan
-
Threonine
Pregunta 11
Pregunta
An alpha-helix is stabilized by __________________.
Respuesta
-
Hydrogen bonding between peptide-bond carbonyl oxygens and amide hydrogens
-
Disulfide bond formation between cysteine residues located 4 amino acids away from each other
-
Hydrophobic interactions between non polar side chains
-
All of the above
-
None of the above
Pregunta 12
Pregunta
A(n) _______________ can be formed from two or more separate polypeptide chains (or segments of polypeptide chains) arranged either in a parallel or in an anti-parallel manner relative to each other.
Respuesta
-
Alpha-helix
-
Beta-sheet
-
Both alpha and beta
-
Neither alpha nor beta
Pregunta 13
Pregunta
_________ structure can be possibly stabilized by covalent bonds, hydrophobic interactions, hydrogen bonds, or ionic interactions
Respuesta
-
Tertiary
-
Quaternary
-
Both T and Q
-
Neither T nor Q
Pregunta 14
Pregunta
A monomeric protein is denatured by exposure to a chaotropic agent. This act of denaturation can result in the unfolding and disorganization of the protein's ____________.
Respuesta
-
Secondary
-
Tertiary
-
Both
-
Neither
Pregunta 15
Pregunta
Which of the following statements about beta-amyloid is (are) true?
Respuesta
-
It is a highly denatured peptide that consists of many different random conformations
-
It is associated with the deposition of plaques inside certain key neurons
-
It always results from a genetically encoded amino acid substitution
-
All of the above are true
-
None of the above are true
Pregunta 16
Pregunta
Which of the following statements about prions is (are) true?
Respuesta
-
The prion genome consists of a single molecule of RNA
-
The prion genome codes for an inherently unstable peptide
-
Both statements are true
-
Neither statement is true
Pregunta 17
Pregunta
One is comparing the noninfectious, normal PrP in a healthy brain to the infectious PrP. The infectious PrP ___________ relative to the normal PrP
Respuesta
-
Exhibits less resistant to proteolytic degradation
-
Exhibits a greater tendency to form insoluble aggregates of fibrils
-
Both
-
Neither
Pregunta 18
Pregunta
The reaction A-B + water ---> A-OH + B-H is enzymatically mediated by a(n) ___________.
Respuesta
-
Isomerase
-
Ligase
-
Transferase
-
Hydrolase
-
None of the above
Pregunta 19
Pregunta
An enzyme binds its substrate under optimal conditions. Upon this binding, which of the following will subsequently occur?
Respuesta
-
An enzyme-substrate complex is produced
-
Binding of the substrate causes a conformational change in the enzyme
-
Enzyme-substrate complex is converted to an enzyme-product complex
-
All statements are true
-
None are true
Pregunta 20
Pregunta
An enzyme functions by ______________
Respuesta
-
Increasing the free energy of activation
-
Decreasing the free energy of the reactants
-
Increasing the free energy of the product
-
All statements are true
-
None of the statements are true
Pregunta 21
Pregunta
Which of the following statements about the tau protein is (are) true?
Respuesta
-
The normal version of tau helps in the assembly and stabilization of the intracellular micro tubular structure
-
The abnormal tau results from the substitution of a valine to a glutamate
-
The abnormal tau is hypophosphorylated (fewer phosphates than normal) and is highly soluble
-
All are true
-
None are true
Pregunta 22
Pregunta
Protein X is a large and complex polypeptide. X's secondary and tertiary structure would be potentially altered the most by the substitution of a single ______ for a single ________
Respuesta
-
arginine, lysine
-
alanine, valine
-
glutamate, aspartate
-
serine, proline
-
glutamine, asparagine
Pregunta 23
Pregunta
Which of the following statement(s) about amino acids is (are) correct?
Respuesta
-
Certain amino acids can function in neurotransmission
-
Certain neurotransmitters are derived from amino acids
-
Certain hormones are derived from amino acids
-
Certain amino acids are not incorporated into proteins (non-proteogenic)
-
All are correct
Pregunta 24
Pregunta
Which of the following statements is (are) correct?
Respuesta
-
Glycine is not a chiral molecule
-
Glycine can be found in both an L and D form in many human proteins
-
Glycine has an asymmetric center at the alpha carbon
-
All are correct
-
None are correct
Pregunta 25
Pregunta
Which of the following amino acids would be least likely to be found on the outside surface of a protein buried inside of a hydrophobic environment?
Respuesta
-
Tyrosine
-
Phenylalanine
-
Leucine
-
Tryptophan
-
Alanine
Pregunta 26
Pregunta
The formation of a disulfide bond by the oxidation of two ______ residues can contribute to the stability of proteins
Respuesta
-
Methionine
-
Proline
-
Cysteine
-
Histidine
-
All options
Pregunta 27
Pregunta
Which of the following statements about amino acids is (are) correct?
Respuesta
-
The side chains of certain amino acids contain a carboxylate group
-
The side chains of certain amino acids contain an amide group
-
The side chains of certain amino acids contain polar hydroxyl groups, which can serve as sites of attachment for compounds that are not amino acids
-
All are correct
-
None are correct
Pregunta 28
Pregunta
Which one of the following statements about protein structure is correct?
Respuesta
-
Proteins consisting of one polypeptide can have quaternary structure
-
The formation of a disulfide bond in a protein requires that the two participating cysteine residues by adjacent to each other in the primary sequence of the protein
-
The stability of quaternary structure in proteins is mainly a result of covalent bonds among the subunits
-
The denaturation of proteins always leads to irreversible loss of secondary and tertiary structure
-
The information required for the correct folding of a protein is contained in the specific sequence of amino acids along the polypeptide chain
Pregunta 29
Pregunta
Which one of the following statements is correct?
Respuesta
-
The alpha-helix can be composed of more than one polypeptide chain
-
B-sheets exist only in the anti-parallel form
-
There are 3.6 amino acids in each turn of an alpha helix
-
Domains are a type of secondary structure
-
The alpha-helix is stabilized primarily by ionic interactions between the side chains of amino acids
Pregunta 30
Pregunta
Which of the following statements about the normal form of PrP is (are) correct?
Respuesta
-
It has a different gene sequence relative to the infectious form
-
It has a different amino acid sequence relative to the infectious form
-
It has fewer B-sheets and more A-helices than the infectious form
-
It is more resistant to proteolytic degradation than the infectious form
-
It plays a significant role in the development of Alzheimer disease
Pregunta 31
Pregunta
A peptide bond:
Respuesta
-
Has partial double bond character
-
Is ionized at physiological pH
-
Is cleaved by agents that denature proteins, such as organic solvents and high concentrations of urea
-
Is stable to heating in strong acids
-
Most commonly in the cis configuration
Pregunta 32
Pregunta
Which of the following statements about the alpha-helix is (are) correct?
Respuesta
-
The sequence of amino acids in the alpha-helix always shows a predictable pattern of specific amino acids throughout the length of the entire helix
-
The formation of the alpha-helix is always mediated by the enzymatic activity of enzymes known as alpha-helicases
-
Approx. 50% of the alpha-helices are found in a parallel configuration, while about 50% are in anti-parallel configuration
-
All are correct
-
None are correct
Pregunta 33
Pregunta
Which of the following interactions can cooperate in the stabilization of the tertiary structure:
Respuesta
-
Ionic interactions between negatively charged and positively charged side chains
-
Hydrophobic interactions between different non polar side chains
-
Disulfide covalent linkages between two noncontiguous cysteine residues
-
All cooperate
-
None of the options cooperate
Pregunta 34
Pregunta
Which of the following statements about the neurofibrillary tangles associated with Alzheimer disease is (are) correct?
Respuesta
-
The neurofibrillary tangles are extra-cellular aggregates that tend to accumulate both in the brain and other regions of the central nervous system
-
There is significant evidence that these neurofibrillary tangles are usually caused by the ingestion of a pathogenic protein known as tau
-
The neurofibrillary tangles are generally intertwined with the intra-cellular amyloid plaque
-
All are correct
-
None are correct
Pregunta 35
Pregunta
Which of the following is the least likely to be disrupted by denaturation of a protein?
Respuesta
-
Disulfide bonds
-
Hydrophobic interactions
-
Peptide bonds
-
Weak noncovalent interactions
-
Hydrogen bonds
Pregunta 36
Pregunta
The addition of a hydroxyl to __________ produces tyrosine
Respuesta
-
Valine
-
Tyrosine
-
Phenylalanine
-
Glycine
-
Proline
Pregunta 37
Pregunta
This is an optically inactive amino acid
Respuesta
-
Valine
-
Tyrosine
-
Phenylalanine
-
Glycine
-
Proline
Pregunta 38
Pregunta
This is the precursor of dopamine, epinephrine, and norepinephrine
Respuesta
-
Valine
-
Tyrosine
-
Phenylalanine
-
Glycine
-
Proline
Pregunta 39
Pregunta
An example of an imino acid
Respuesta
-
Valine
-
Tyrosine
-
Phenylalanine
-
Glycine
-
Proline
Pregunta 40
Pregunta
Branched chain amino acid
Respuesta
-
valine
-
tyrosine
-
phenylalanine
-
glycine
-
proline
Pregunta 41
Pregunta
Protein P is a protein found inside a lipid environment. Which of the following amino acids would be most likely to be found on the outside surface of P
Respuesta
-
Aspartic acid
-
lysine
-
isoleucine
-
asparagine
-
arginine
Pregunta 42
Pregunta
Drug D has one ionizable group, an amino group, with a pKa of 9.0. This drug can pass through cell membranes most readily when uncharged. Theoretically, passage of the drug would occur most readily at pH ___________.
Respuesta
-
2.5
-
4.5
-
6.5
-
7.5
-
9.3
Pregunta 43
Pregunta
Which of the following amino acids participates the most in protein buffering of blood?
Respuesta
-
histidine
-
proline
-
alanine
-
tryptophan
-
phenylalanine
Pregunta 44
Pregunta
PrP(Sc) is the causative agent of transmissible spongiform encephalopathies because of:
Respuesta
-
A single point mutation in the gene coding for the PrP(Sc)
-
The ability of the PrP(Sc) to complex with an infectious molecule of nucleic acid
-
A higher proportion of alpha-helical structures in the PrP(Sc)
-
All are correct
-
None are correct
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