Exam 1 Flashcards
1
Q
If a reaction has a negative delta G, is it spontaneous?
A
The reaction is spontaneous because the delta G is negative.
2
Q
______ is the free energy of the reaction under the actual reaction conditons
A
Delta G
3
Q
______ is the free energy under the standard states.
A
Delta G degree
4
Q
______ is the free energy under the biochemical standard states.
A
Delta G degree prime
5
Q
______ is the free energy of the transition state.
A
Delta G transition symbol
6
Q
When the reaction conditions match the biochemical standard states, the values of _____ and _____ will be equal.
A
Delta G and Delta G degree prime
7
Q
The _____ determines the rate constant, while _____ determines the favorability of a reaction under standard conditons.
A
Delta G transition and Delta G degree
8
Q
An endergonic reaction with a ______ Delta H and a ______ Delta S can be changed into an exergonic reaction by decreasing the temperature.
A
negative; negative
9
Q
For the reaction phosphoenolpyruvate + ADP + H+ –> pyruvate + ATP, if Keq>1, which of the following conditions is TRUE?
-[pyruvate][ATP] > [phosphoenolpyruvate][ADP][H+}
-[pyruvate][ATP] < [phosphoenolpyruvate][ADP][H+}
-[pyruvate][ATP] = [phosphoenolpyruvate][ADP][H+}
-none of the above
A
[pyruvate][ATP] > [phosphoenolpyruvate][ADP][H+}
10
Q
Change in enthalpy (Delta H) is best defined as _____.
-the sum of heat absorbed and work done
-the heat transferred at constant pressure
-the pressure change at constant temperature
-the measure of disorder in a system
-none of the above
A
The heat transferred at constant pressure
11
Q
For a reaction with Delta H=23 kJ/mol and Delta S=22 J/L mol, at 2 degrees Celsius, the reaction is ____.
-spontaneous
-nonspontaneous
-at equilibrium
-impossible to determine reactivity
-none of the above
A
Nonspontaneous
12
Q
A spontanous process always has ____.
-Delta G < 0
-Delta G > 0
-Delta H < 0
-Delta H > 0
-none of the above
A
Delta G < 0
13
Q
Is adenine a purine or pyrimidine?
A
Purine
14
Q
What is the name of the molecule that is composed of adenine linked to the C-1’ of ribose?
A
Adenosine
15
Q
In the structure of DNA, the bases in complementary strands interact through _______, while the bases within one strand interact through _________. Lastly, phosphodiester groups interact with magnesium ions through _________.
A
-hydrogen bonds
-pi-pi interactions
-ionic interactions
16
Q
In order to perform PCR, which of the following describes the reagents that must be included in the reaction mixture?
-DNA fragment, primers flanking the region of interest, dNTPs, DNA polymerase
-DNA fragment, primers flanking the region of interest, dNTPs, ddNTPs, DNA polymerase
-DNA fragment, one primer, dNTPs, DNA polymerase, DNA ligase
-DNA fragment, primers flanking the region of interest, dNTPs, DNA ligase
-None of the above
A
DNA fragment, primers flanking the region of interest, dNTPs, DNA polymerase
17
Q
EcoRI recognizes the sequence 5’G arrow AATTC-3’ (arrow indicates the point of cleavage). Treatment of the following oligonucleotide with EcoRI would produce two oligonucleotides with sizes of _____ nucleotides containing _____ ends.
5’- AAGTCGATACAGAATTCGTACCTAG-3’
-12 and 13; sticky
-11 and 8; sticky
-12 and 8; blunt
-9 and 13; sticky
-12 and 13; blunt
A
12 and 13; sticky
18
Q
Which component is not necessary for transformation?
-foreign DNA
-growth media
-plasmid
-gene gun
A
Gene gun
19
Q
Which of the following statements is TRUE regarding phosphodiester bonds that link adjacent nucleotides in both RNA and DNA?
-Phosphodiester bonds join the 3’ hydroxyl of one nucleotide to the 5’ hydroxyl of the next
-Phosphodiester bonds are uncharged at pH 7.0
-Phosphodiester bonds always link G with C and A with either T or U
-Phosphodiester bonds are positively charged.
A
Phosphodiester bonds join the 3’ hydroxyl of one nucleotide to the 5’ hydroxyl of the next
20
Q
Phosphodiester bonds link DNA monomers to form a polymer by which mechanism?
-The OH group on the C-2 in the 2-deoxyribose monosaccharide forms a covalent to elongate the DNA polymer
-The OH group on the C-3 in the ribose carbohydrate forms a covalent to elongate the DNA chain
-The OH group on the C-3 in the 2-deoxyribose carbohydrate forms a covalent to elongate the DNA chain
-The OH group on the C-2 in the ribose carbohydrate forms a covalent to elongate the DNA polymer
A
The OH group on the C-3 in the 2-deoxyribose carbohydrate forms a covalent to elongate the DNA chain
21
Q
Which of the following statements is most correct?
-DNA polymerase can only add a nucleotide to the free 5’-OH group of a base-paired polynucleotide
-DNA polymerase can only add a nucleotide to the free 3’-OH group of a base-paired polynucleotide
-DNA polymerase can only add a nucleotide to the free 3’-OH group of a polynucleotide that is not base-paired
-DNA polymerase can only add pyrophosphate to the free 3’-OH group of a base-paired polynucleotide
A
DNA polymerase can only add a nucleotide to the free 3’-OH group of a base-paired polynucleotide
22
Q
DNA polymerase from Thermus aquaticus is used in PCR because
-the enzyme is readily deactivated by heat, effectively halting the reaction
-the genes from Thermus aquaticus are readily distinguished from those of ‘normal’ organisms
-it is stable at high temperatures
-it is not infectious
-it is a soluble protein
A
It is stable at high temperatures
23
Q
DNA ______ is an enzyme necessary for splicing together fragments of DNA with complementary ends.
A
ligase
24
Q
Which of the following is a function of the ribosome?
-binds mRNA and allows codon recognition
-mediates the binding of proteins necessary for initiation, elongation, and termination
-catalyzes the synthesis of peptide bonds
-translocate such that multiple codons can be read
A
All of the above
25
Which level of protein architecture is composed of multiple subunits in a protein?
-tertiary
-quarternary
-primary
-secondary
Quareternary
26
RNA occurs primarily as single-stranded molecules that can give rise to ____ structures.
-tautomeric
-parallel
-haploid
-stem-loop
-diploid
Stem-loop
27
The pyrimidine found in both DNA and RNA is ______.
cytosine
28
The pyrimidine found only in DNA is _______.
thymine
29
The pyrimidine found only in RNA is ______.
uracil
30
Which one of the following statements about peptide bonds is FALSE. Peptide bonds are:
-rigid and planar, with partial double-bond character
-charged
-amides
-covalent
-involved in forming the primary structure of proteins
Charged
31
Which of the following statements BEST describes a prosthetic group?
-They are the active part of an enzyme
-They are nonpeptide molecules or ions critical to a protein's structure
-They are short peptide chains attached to a larger protein
-They are nonfunctional components of a protein
They are nonpeptide molecules or ions critical to a protein's structure
32
The _____ character of most standard amino acids causes solutions of amino acids to rotate the plane of polarized light.
-chiral
-zwitterionic
-polar
-hydrophobic
-none of the above
Chiral
33
For the reaction H+ (aq) + HCO3- (aq) <--> H2CO3 (aq), if the reaction is at equilibrium, which conditions must be maintained?
-[H2CO3] > [H+][HCO3-]
-[H2CO3] < [H+][HCO3-]
-[H2CO3] = [H+][HCO3-]
-none of the above
[H2CO3] > [H+][HCO3-]
34
Please rank the following acids in order of increasing pKa.
-CH3COOH, HF, HCl, H2O
-HF, HCl, H2O, CH3COOH
-H2O, CH3COOH, HF, HCl
-HCl, HF, CH3COOH, H2O
HCl, HF, CH3COOH, H2O
35
Guanine, a DNA base, tightly bonds to cytosine through which intermolecular forces?
-covalent bonding
-dipole-dipole interactions
-hydrogen bonding
-London dispersion forces
Hydrogen bonding
36
The second law of thermodynamics states ____.
-that spontaneous processes are characterized by the overall conversion of order to disorder
-that spontaneous processes are characterized by the conversion of work to force
-that nonspontaneous processes are characterized by the conversion of order to disorder
-that spontaneous processes are characterized by the conversion of heat to pressure
-none of the above
That spontaneous processes are characterized by the overall conversion of order to disorder
37
Change in enthalpy (Delta H) is best defined as ____.
-the sum of heat absorbed and work done
-the heat transferred at constant pressure
-the pressure change at constant temperature
-the measure of disorder in a system
-none of the above
The heat transferred at constant pressure
38
A spontaneous process _____.
-occurs without the addition of free energy
-has a Delta G < 0
-is exergonic
-is all of the above
-is none of the above
Is all of the above
39
The term used to indicate the degree of randomness within a system is _____.
entropy
40
Spontaneous processes are characterized by a change in Gibbs free energy that is ______.
negative
41
The symbol for free energy under standard biochemical conditions is ______.
-Delta H degree prime
-Delta G degree prime
-Delta T
-Delta H
-is none of the above
Delta G degree prime
42
For a reaction with Delta H = 23 kJ/mol and Delta S = 22 J/K mol, at 2 degrees Celsius, the reaction is _____.
-spontaneous
-nonspontaneous
-at equilibrium
-impossible to determine reactivity
-none of the above
nonspontaneous
43
An increase in disorder in the system _____.
-is required for a process to be spontaneous
-results in a decrease in entropy
-is characteristic of a system increasing in enthalpy
-results in the factor T Delta S being positive
-is found in every exergonic process
Results in the factor T Delta S being positive
44
The ketone body Beta-hydroxybutyrate is a small molecule found in some metabolic states. In organisms, Beta-hydroxybutyrate will spontaneously decarboxylate into acetone and carbon dioxide. Which of the rate laws best describes this overall reaction?
-Rate = k[Beta-hydroxybutyrate]
-Rate = k[Beta-hydroxybutyrate]^2
-Rate = k[acetone][CO2]
-Rate = k[Beta-hydroxybutyrate][acetone][CO2]
-Rate = k([acetone][CO2])/[Beta-hydroxybutyrate])
Rate = k[Beta-hydroxybutyrate]
45
Read the following 3 statements and determine which are true and false.
i.) Nucleic acids are synthesized in the 3'-5' direction.
ii.) The sugar-phosphate groups which form the "backbone" of the DNA double-helix are located on the outside of the helix because they are polar.
iii.) RNA polymerase "reads" a template strand by running along it in a 5'-3' direction.
ii is true
i and iii are false
46
Which of the following does NOT apply to the reaction catalyzed by a DNA polymerase?
-It is a phosphoryl group transfer reaction.
-It involves a nucleophilic attack by an -OH group.
-It is a biosynthetic (anabolic) reaction and so has a positive free energy change (Delta G).
-It is facilitated by the hydrolysis of a pyrophosphate group.
-It requires an abundant supply of deoxynucleoside triphosphates.
It is a biosynthetic (anabolic) reaction and so has a positive free energy change (Delta G).
(While the reaction catalyzed by DNA polymerases is biosynthetic, reactions in biological systems cannot proceed unless they have an overall negative free energy change.)
47
What is the function of a restriction enzyme?
-It seals breaks in the sugar-phosphate backbone.
-It cuts DNA.
-It adds a nucleotide base to the template strand of DNA.
-It unwinds DNA.
It cuts DNA.
48
Why does the polymerase chain reaction require a heat-stable DNA polymerase?
-High temperatures are necessary to cause strand separation after each cycle of synthesis.
-High temperatures are necessary for annealing primers.
-High temperatures are necessary for initiating DNA synthesis.
-High temperatures are necessary for high-fidelity in DNA synthesis.
High temperatures are necessary to cause strand separation after each cycle of synthesis.
49
Nucleotides play a central role in living organisms because ____.
-they mediate transport of energy within the cell
-they are involved in oxidation-reduction reactions
-they are involved in intracellular signaling
-they function as building blocks for nucleic acids
-all of the above
All of the above
50
Inside our cells, free nucleotides are almost always associated with ____.
-proteins
-cholesterol
-Cl- counterions
-fatty acids
-Mg2+ counterions
Mg2+ counterions
51
Nucleoside triphosphates are useful for energy transfer because the phosphoanhydride bonds are relatively _____.
-stable
-high energy
-biocampatible
-large
-low energy
High energy
52
Which of the following nucleotides contain energy rich bonds?
-ATP
-TTP
-CTP
-GTP
-all of the above
All of the above
53
Which of the following molecules does not contain an energy-rich phosphoanhydride bond?
-ADP
-GDP
-AMP
-CDP
-all of the above
AMP
54
DNA forms a double _____.
helix
55
The two strands run _____.
antiparallel
56
The sugar is ______.
deoxyribose
57
The sugar-phosphate groups are _______.
on the outside of the helix
58
The bases are _______.
in the center of the helix
59
The bases are planar, and their plane is oriented ______ to the axis of the helix.
perpendicular
60
The helix has a minor and major _____ on its surface.
groove
61
The link between a purine and ribose is made from the _____ of the purine ring to the _____ of the ribose.
N-9 and C-1'
62
In DNA, the ribose derivative lacks an _____ on C-_____.
-alcohol; 2
-alcohol; 3
-amine; 2
-amine;3
-none of the above
Alcohol; 2
63
What type of bond is made between nucleotides?
-ester
-phosphoester
-phosphodiester
-glycosidic
-none of the above
Phosphodiester
64
The most common base pairs in DNA are ____ and ____.
C-G and T-A
65
An A-T base pair consists of _____ H-bonds and a G-C base pair consists of ____ H-bonds.
2 and 3
66
Which of the following correctly describes the B-DNA double helix?
-antiparallel strands
-right-handed helix
-base pairs are located in the center of the helix
-one helical rotation has a rise of 3.4 nm
-all of the above
All of the above
67
The replication of DNA is made possible by the presence of ____ strands in the double helix of DNA.
complementary
68
In living organisms, genetic information is most often stored in the form of _____.
-ribonucleic acid
-deoxyribonucleic acid
-proteins
-enzymes
-deoxynucleotides
Deoxyribonucleic acid
69
An E. coli has ____ replication forks on its single chromosome; humans have _____ replication forks on each chromosome.
2; many
70
Which strand of DNA is replicated exclusively in a discontinuous fashion?
-forward strand
-reverse strand
-leading strand
-laggin strand
-the strand that is read in a 5' to 3' direction
Lagging strand
71
Which of the following best describes a new strand of DNA relative to the template strand used to synthesize it?
-an exact duplicate of the template
-a negative copy of the template
-a palindromic copy of the template
-an exact copy of the template but with the 3' and 5' ends reversed
-none of the above
A negative copy of the template.
72
In most organisms, replication proceeds in a ____ manner from the ____.
-bidirectional; replication origin
-bidirectional; theta site
-bidirectional; lagging strand
-unidirectional; chromosome ends
-none of the above
Bidirectional; replication origin
73
Incorporation of which of the following would result in chain termination during sequencing of DNA?
-dATP
-dCTP
-ddTTP
-dGTP
-none of the above
ddTTP
74
The results of DNA sequencing are obtained by first separating different-sized pieces of DNA using _____ followed by detection of the particular dideoxynucleotide using ______.
-HPLC; NMR
-HPLC; absorbance spectroscopy
-electrophoresis; fluorescence spectroscopy
-electrophoresis; X-ray crystallography
-none of the above
electrophoresis; fluorescence spectroscopy
75
The most commonly used technique for making large numbers of copies of DNA is ____.
-polymerase chain reaction
-dideoxy-sequencing
-restriction digestion
-genetic engineering
-site-directed mutagenesis
Polymerase chain reaction
76
What reagents are required to perform PCR?
-DNA fragment, primers flanking the region of interest, dNTPs, DNA polymerase
-DNA fragment, primers flanking the region of interest, dNTPs, ddNTPs, DNA polymerase
-DNA fragment, one primer, dNTPs, DNA polymerase, DNA ligase
-DNA fragment, one primer, dNTPs, DNA polymerase, DNA endonuclease
-DNA fragment, primers flanking the region of interest, dNTPs, DNA endonuclease
DNA fragment, primers flanking the region of interest, dNTPs, DNA polymerase
77
Which of the following represents the correct order of steps in a PCR reaction beginning with double-stranded DNA?
-primer annealing, strand separation, primer extension
-strand separation, primer extension, primer annealing
-strand separation, primer annealing, primer extension
-primer extension, primer annealing, strand separation
-primer annealing, primer extension, strand separation
strand separation, primer annealing, primer extension
78
What term describes the production of multiple identical organisms from a single ancestor?
-transcription
-cloning
-sequencing
-phenotyping
-ligation
Cloning
79
Double-stranded DNA molecules can be cleaved at specific recognition sites by _____.
-RNA polymerase
-DNA ligase
-DNA polymerase
-reverse transcriptase
-Type II restriction endonucleases
Type II restriction endonucleases
80
DNA sequencing by the chain-termination method uses DNA polymerase I to make a complementary copy of the target or template DNA molecule. A reaction with a 20 bp template and dideoxyadenosine nucleotides as terminators results in the production of a 5 bp fragment. Based on this result, we can conclude that the template contains _____.
-a cytosine at position 5
-a thymine at position 5
-a cytosine at position 16
-a thymine at position 16
-a uracil at position 5
A thymine at position 16
81
In molecular cloning, transformed organisms must be identified. One common method for accomplishing this involves the inclusion of ______ in the plasmid.
-a restriction site
-a nuclease gene
-a deletion
-an origin of replication
-an antibiotic resistance gene
An antibiotic resistance gene
82
What are the steps of DNA replication?
1. Formation of a replication bubble
2. Replication of the leading and lagging strand in 5' to 3' direction
3. Ligation of the replicated strands on the lagging strand.
83
A PCR experiment was performed on a highly conserved gene from two species, one prokaryotic and one eukaryotic. Which of the following statements best describes the expected results?
-The sequences of the PCR products would be identical
-The sequences of the PCR products would be mostly identical except for any random mutations.
-The sequences of the PCR product would be different since eukaryotes have introns and exons.
-The sequences of the PCR products would be different since prokaryotes have introns and exons.
The sequences of the PCR product would be different since eukaryotes have introns and exons.
84
Which statement is TRUE for RNA but not DNA?
-RNA uses 2-deoxryribose sugar.
-RNA uses uracil as a nitrogenous base
-RNA is created from DNA in a process known as translation
-RNA is the only nucleic acid that can be absorbed in the UV spectrum
RNA uses uracil as a nitrogenous base
85
RNA occurs primarily as single-stranded molecules that can give rise to _____ structures.
-diploid
-stem-loop
-parallel
-tautomeric
-haploid
Stem-loop
86
Genomic DNA is ____, resulting in the production of _____.
-transcribed; mRNA
-translated; tRNA
-transcribed; protein
-translated; protein
-translated; rRNA
transcribed; mRNA
87
Polypeptide synthesis proceeds from the ____ to the ____.
-entrance site; exit site
-50S subunit; 30S subunit
-C-terminus; N-terminus
-N-terminus; C-terminus
-peptidyl site; aminoacyl site
N-terminus; C-terminus
88
What are the 3 types of RNA that are directly involved in translation?
mRNA. rRNA, tRNA
89
_____ moves genetic information from the nucleus to the ribosomes in the cytoplasm.
mRNA
90
______ decodes the genetic message; it matches sequences of 3 nucleotides to amino acids.
tRNA
91
_____ is involved in the catalysis of amide bond formation
rRNA
92
In bacteria, riboflavin can inhibit its own synthesis by binding to an mRNA element termed a _______.
riboswitch
93
RNA interference is a mechanism of post-transcriptional RNA-dependent ______.
-chromatin-remodeling
-gene silencing
-histone methylation
-coactivation
-apoptosis
gene silencing
94
What is the region immediately adjacent to the starting site for RNA polymerization called?
-promoter
-enhancer
-initiator
-consensus sequence
-TF binding site
Promoter
95
Two amino acids of the standard 20 contain hydroxyl-groups. They are...
threonine and serine
96
At a pH above its pKa, the phenol group of tyrosine is ______.
deprotonated
97
A typical protein weighs _____ daltons.
50,000
98
Which statement is most TRUE regarding peptide bonds?
-They are amide linkages that connect amino acids.
-They are flexible linkages that rotate around the sp2 bond in the carbonyl carbon
-They are composed of an electronegative carbonyl group and an electropositive nitrogen atom.
-They are weaker than London dispersion forces.
They are amide linkages that connect amino acids.
99
In the tripeptide Lys-Pro-Ile, the C-terminal residue is ______.
Isoleucine
100
The formation of a dipeptide from two amino acids involves
-side-chain complementarity
-loss of water
-oxidation of the alpha carbon
-reduction of the alpha carbon
-base catalysis
Loss of water
101
Which one of the following statements about peptide bonds is FALSE. Peptide bonds are
-rigid and planar, with partial double-bond character
-charged
-covalent
-involved in forming the primary structure of proteins
-amides
charged.
102
Which of the following statements BEST describes a prosthetic group?
-They are nonpeptide molecules or ions critical to a protein's structure.
-They are short peptide chains attached to a larger protein.
-They are nonfunctional components of a protein
-They are the active part of an enzyme
They are nonpeptide molecules or ions critical to a protein's structure.
103
Which of the following are methods of denaturing a protein?
-pH changes
-heat
-mechanical agitation
-all of the above
All of the above
104
Why do detergents denature proteins?
-The primary structure of the protein can cause alterations in the charges of the residues.
-The secondary structure can be altered because of disruptions in the hydrogen bonding.
-The forces stabilizing the tertiary structure are disrupted, changing the conformation of the protein.
-The quarternary structure can be modified because of the deprotonation of prosthetic groups.
The forces stabilizing the tertiary structure are disrupted, changing the conformation of the protein.
105
Two cysteine residues would most likely result in what type of bonding?
-hydrogen bond
-disulfide bond
-dispersion forces
-salt bridges
Disulfide bond
106
The simplest protein structure is ____ structure.
primary
107
The overall charge of the polypeptide His-Tyr-Lys-Met-Ile-Glu at pH 6.9 is ____?
0
108
Which level of protein structure is defined as "the hydrogen bonded arrangement of the polypeptide backbone"?
Secondary
109
Why does a decrease in pH alter/disrupt the tertiary structure of an enzyme?
-It reduces disulphide bonds
-It promotes proteolytic cleavage of peptide bonds
-It disrupts ion pairs/salt bridges
-It reduces hydrophobic interactions
-It deprotonates prosthetic groups
It disrupts ion pairs/salt bridges.
(Ion pairs/salt bridges are relatively weak, non-covalent interactions between charged R groups which play a role in fine-tuning protein tertiary structure. Because the charge of some amino acid R groups is sensitive to pH, changes in pH may disrupt these bonds and alter the protein's tertiary structure.)
110
Zwitterions are ____.
-amino acids
-ionic molecules that are racemic
-ions that bear both negatively and positively charged groups
-side-chain carboxylate anions
-delocalized ions
Ions that bear both negatively and positively charged groups
111
Which of the 20 standard amino acids is optically inactive?
Gly
112
Which amino acid has a charged polar side chan at pH 7.0?
Glu
113
Which amino acid has a sulfur atom in its side chain?
Met
114
At a pH above its pKa, the R-group of Asp is ______.
deprotonated and negatively charged.
115
Leucine has a _____ side chain.
nonpolar
116
Glutamate has a _____ side chain.
charged
117
At physiological pH, all amino acids have at least _____ charged groups.
2
118
In general, amino acids are ____ molecules that act as building blocks for proteins.
chiral
119
Amino acids and amino acid derivative can act as ________ such as hormones or neurotransmitters.
extracellular messenger molecules
120
Do ribosomes use L or D amino acids for protein synthesis?
L
121
What amino acid/amino acid derivative can act as neurotransmitters?
glycine
glutamate
gamma-aminobutyric acid (GABA)
122
The peptide AYDG has an N-terminal _____ residue.
alanine
123
Which tripeptide would be expected to be the most hydrophobic?
GYA
124
The predominant noncovalent interaction seen in alpha helices and beta sheets is ____.
hydrogen bond
125
Which amino acid is generally absent from an alpha helix?
Pro
126
Alpha helices and beta sheets constitute ____ structure.
secondary
127
Which of the following best describes the peptide backbone in a beta sheet?
-coiled
-compacted
-highly extended
-rigid
-none of the above
Highly extended
128
In a protein, the most conformationally restricted amino acid is ____; the least conformationally restricted is _____.
Pro; Gly
129
Which of the following statements is not accurate when considering water and biological molecules?
-Water is more likely to act as a hydrogen bond donor than a hydrogen bond acceptor
-Polar substances are soluble because of their interaction with water
-The hydrogen bonding pattern of water is disrupted by the presence of hydrophobic molecules
Water is more likely to act as a hydrogen bond donor than a hydrogen bond acceptor.
(Water molecules are equally likely to act as either a hydrogen bond donor or acceptor.)
130
According to the Brosted-Lowry definition, a _____ is a substance that can accept a proton.
base
131
Which of the following explains the interactions that occur between the atoms of water molecules and the ions that form when sodium chloride dissolves in water?
-Hydrogens interact with the sodium ion; oxygens interact with the chloride ion
-Hydrogens interact with the chloride ion; oxygens interact with the sodium ion
-Hydrogens interact with the sodium and chloride ions.
-Oxygens interact with the sodium and chloride ions
-None of the above
Hydrogens interact with the chloride ion; oxygens interact with the sodium ion.
132
Which functional group has two hydrogen bond donors and one hydrogen bond acceptor?
amine
133
The boiling point of water is 264 degrees celsius higher than the boiling point of methane because _____.
-the molecular mass of methane is much lower than that of water
-methane molecules tend to avoid contact with each other
-water molecules are connected to each other by H-bonds
-Methane molecules do not undergo London dispersion forces
water molecules are connected to each other by H-bonds
134
What is the conjugate acid of H2PO4-?
H3PO4
135
What shows the buffer that is found in the bloodstream?
H2CO3 <--> HCO3- + H+
136
In an enzyme catalyzed reaction, the reactant that the enzyme interacts with is called the _____.
substrate
137
The active site for elastase contains valine. Which amino acid would be most likely to bind to the active site?
-Ala
-Asp
-Ser
-Met
Ala
138
Another name for a biological catalyst is a _____.
enzyme
139
For a Michaelis-Menten kinetics enzyme Vmax decreases and Km increases, for which type of inhibition?
-Competitive
-Uncompetitive
-Suicide
-Mixed
Mixed
140
Zinc is required for carbonic anhydrase to properly work. It is an example of a _____.
-cofactor
-coenzyme
-ion catalyst
-suicide inhibitor
Cofactor
141
Which of these amino acid groups would NOT make a good nucleophilic catalyst?
-amino
-sulfhydryl
-imidazole
-methyl
-hydroxyl
Methyl
142
Proton transfer from an acid, lowering the free energy of a reaction's transition state is characteristic of _______
-electrostatic catalysis
-nucleophilic catalysis
-general base catalysis
-general acid catalysis
-concerted acid-base catalysis
General acid catalysis
143
Acid base catalysis may be accomplished by
-active site specificity
-charge delocalization
-buffer effects
-induced strain
-conformational change
Charge delocalization
144
Which statement about phosphorylation is TRUE?
-It is an irreversible covalent modification
-It is carried out by phosphatases
-It can alter the charges on proteins by making them more positively charged
-It can trigger cell signaling cascades and be turned on or off.
It can trigger cell signaling cascades and be turned on or off.
145
Chymotrypsin catalyzes the hydrolysis of a peptide bond and is therefore characterized as an _____
-oxidoreductase
-transferase
-hydrolase
-lyase
-ligase
Hydrolase
146
The highest point in a reaction coordinate diagram represents _______.
-an intermediate of the reaction pathway
-the reactants in an exergonic reaction
-the products in an endergonic reaction
-the transition state
-the overall Delta G for the reaction
The transition state
147
If you add enzymes to a solution containing only the products of a reaction, would you expect any substrate to form?
-It depends on the time interval and temperature of reaction.
-It depends on the concentration of products added
-It depends on the energy difference between E + P and the transition state.
-All of the above may determine if product forms
It depends on the energy difference between E + P and the transition state.
148
If A --> B is a zero order reaction, the rate is dependent on the ______.
rate constant
149
A plot of velocity versus substrate concentration for a simple enzyme-catalyzed reaction produces a ____ curve. This indicates that at some point, the enzyme is _____.
hyperbolic curve; saturated with substrate
150
When a substate and enzyme interact, the first chemical species formed is the _____.
enzyme-substrate complex
151
Which of the following expresses the velocity for an enzyme-catalyzed reaction that obeys Michaelis-Menten kinetics?
-v = k1[E][S]
-v = k1 [E][S] - k-1[ES]
-v = k2 [ES]
-v = k1[E][S] + k2[ES]
v = k2 [ES]
152
Which equation must be true if the steady state assumption is to be used?
-
d [ES] / dt = 0
153
The Michaelis constant is defined as...
KM = (k2 + k-1) / k1
154
What equation properly expresses the Michaelis-Menten equation?
v0 = Vmax [S] / (KM + [S])
155
KM is ____.
the [S] that half saturates the enzyme
156
A Lineweaver-Burk plot is a ____.
-double reciprocal plot
-Michaelis-Menten plot
-sigmoidal plot
-hyperbolic plot
-logarithmic plot
Double reciprocal plot
157
Which of the following indicates that an enzyme has evolved to its most efficient form?
-kcat is a large number
-KM is a small number
-KM is a large number
-kcat/KM is a small number
-kcat/KM is near the diffusion-controlled limit
kcat/KM is near the diffusion-controlled limit
158
An extremely efficient enzyme has a _____ KM and a _____ kcat.
small; large
159
Some irreversible inhibitors are called ______ because they bind to the active site of the enzyme and begin the catalytic process, just like a normal substrate.
suicide substrate
160
Which is the conjugate base in the product of the following reaction:
H2SO4 + H2O --> HSO4- + H3O+
HSO4-
161
For a Michaelis-Menten enzyme, the inhibitor binds to the enzyme at the active site in which type of inhibition?
Competitive
162
Which amino acid is most likely to act as a covalent catalyst in an enzyme active site?
-Ala
-Met
-Ile
-Ser
Ser
163
Which statement best describes the model of "induced fit"?
-Enzyme-substrate binding induces formation of the transition state, which reduces the free energy of the reaction.
-Enzyme-substrate binding induces enzyme specificity
-Enzyme-substrate binding induces a conformational change in the enzyme, such that the binding site better conforms to the shape of the substrate.
-Enzyme-substrate binding induces an increase in the reaction entropy.
Enzyme-substrate binding induces a conformational change in the enzyme, such that the binding site better conforms to the shape of the substrate.
164
For a Michaelis-Menten enzyme, the inhibitor binds to the enzyme-substrate complex in which type of inhibition?
Uncompetitive
165
Which amino acid would most likely participate in general acid-base catalysis under basic conditions?
-Ala
-Tyr
-Leu
-Gln
Tyr
166
Which of these amino acid groups would NOT make a good nucleophilic catalyst?
-methyl
-hydroxyl
-imidazole
-sulfhydryl
-amino
Methyl
