BCH EXAM 1 QUESTIONS AND ANSWERS NEWEST
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Identify the most conservative amino acid substitution, assuming that these two residues occur
at the same position in two homologous proteins.
Glu --> Leu
Glu --> Lys
Glu --> Ala
Glu --> Asp - CORRECT ANSWERS Glu --> Asp
T/F Growth of actin filaments is dynamic and continuous under normal cellular conditions. -
CORRECT ANSWERS True
Which of the following assembles by association of multiple protofilaments?
myosin
actin
tubulin
keratin
collagen - CORRECT ANSWERS tubulin
Each myosin head contains a binding site for _____ and a binding site for _____.
tubulin; GTP
another myosin molecule; ATP
kinesin; GTP
actin; ATP - CORRECT ANSWERS actin; ATP
Which of the two proteins below has a binding site for tubulin?
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Myosin
Kinesin
Both - CORRECT ANSWERS kinesin
Which of the following proteins contain polypeptide chains that associate in a coiled-coil
interaction?
a)Actin
b)Keratin
c)Myosin
d)A and B
e)B and C - CORRECT ANSWERS e
During muscle contraction, hydrolysis of ATP results in a change in the:
conformation of actin
conformation of myosin
structure of myofibrils
structure of the Z disk
none of the above - CORRECT ANSWERS conformation of myosin
For a given reaction, the value of deltaH is 15 kJ/mol and the value of deltaS is 51 J/K mol.
Above what temperature will this reaction be spontaneous? - CORRECT ANSWERS 0 >
15,000 J/mol - (T)(51 J/Kmol)
-15,000 > (T)(51 /K)
15,000 < (T)(51 /K)
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294K < T or T > 294K
294 - 273 = 21C
this reaction is favorable in temps above 21 degrees
Which of the following are insoluble in water?
Alanine (A)
Glucose (G)
Palmitate (fatty acid) (P)
Cholesterol (C) - CORRECT ANSWERS Palmitate (fatty acid) (P)
Cholesterol (C)
highly non polar molecules
Rank the melting points of the following compounds.
a) H3C-CH2-O-CH3
b)H3C-C=O-NH2
c)H2N-C=O-NH2
d)H3C-(CH2)3-CH3
e)H3C-CH2-CH=O - CORRECT ANSWERS c > b > e > a > d
Thermal energy is added in overcome the intermolecular forces holding molecules together.
The higher those forces, the more the T must be raised to overcome those forces. The strongest
intermolecular forces would be ionic - but none of these molecules are charged. The next
strongest type of intermolecular force would be H bonds. Both (b) and (c) can hydrogen bond -
but (c) can to a greater extent. Next, we look for permanent dipoles - like (a) and (e). In this
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case, (e) has a stronger dipole and would therefore have a higher melting point. The weakest
forces are London dispersion - as would be true for (d)
What is the conjugate base of the weak acid H3BO3?
A) BO33-
B) HBO32-
C) H2BO3- - CORRECT ANSWERS c
Which of the following would be the strongest acid?
A) Citrate, pK 4.76
B) Succinic acid, pK 4.21
C) Succinate, pK 5.64
D) Citric acid, pK 3.13
E) Formic acid, pK 3.75 - CORRECT ANSWERS d
What is the pH of a solution of 1.0 x 10-9 M HCl? Express answer as a whole number (no
decimals). - CORRECT ANSWERS The HCl is a strong acid and dissociates completely.
This means that the concentration of hydrogen ions contributed by the HCl is 1.0 x 10-9 M. But
the concentration of the hydrogen ions contributed by the dissociation of water is 100-fold
greater than this: 1.0 x 10-7 M. The concentration of the hydrogen ions contributed by the HCl
is negligible in comparison. Therefore, the pH of the solution is equal to 7.0. Note that this
demonstrates that water, itself, is a buffer! From H2O: 1 x 10-7 M
From HCl: 1 x 10-9 M or 0.01 x 10-7 M
Sum: 1.01 x 10-7 M
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Identify the most conservative amino acid substitution, assuming that these two residues occur
at the same position in two homologous proteins.
Glu --> Leu
Glu --> Lys
Glu --> Ala
Glu --> Asp - CORRECT ANSWERS Glu --> Asp
T/F Growth of actin filaments is dynamic and continuous under normal cellular conditions. -
CORRECT ANSWERS True
Which of the following assembles by association of multiple protofilaments?
myosin
actin
tubulin
keratin
collagen - CORRECT ANSWERS tubulin
Each myosin head contains a binding site for _____ and a binding site for _____.
tubulin; GTP
another myosin molecule; ATP
kinesin; GTP
actin; ATP - CORRECT ANSWERS actin; ATP
Which of the two proteins below has a binding site for tubulin?
,BCH EXAM 1 QUESTIONS AND ANSWERS NEWEST
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Myosin
Kinesin
Both - CORRECT ANSWERS kinesin
Which of the following proteins contain polypeptide chains that associate in a coiled-coil
interaction?
a)Actin
b)Keratin
c)Myosin
d)A and B
e)B and C - CORRECT ANSWERS e
During muscle contraction, hydrolysis of ATP results in a change in the:
conformation of actin
conformation of myosin
structure of myofibrils
structure of the Z disk
none of the above - CORRECT ANSWERS conformation of myosin
For a given reaction, the value of deltaH is 15 kJ/mol and the value of deltaS is 51 J/K mol.
Above what temperature will this reaction be spontaneous? - CORRECT ANSWERS 0 >
15,000 J/mol - (T)(51 J/Kmol)
-15,000 > (T)(51 /K)
15,000 < (T)(51 /K)
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294K < T or T > 294K
294 - 273 = 21C
this reaction is favorable in temps above 21 degrees
Which of the following are insoluble in water?
Alanine (A)
Glucose (G)
Palmitate (fatty acid) (P)
Cholesterol (C) - CORRECT ANSWERS Palmitate (fatty acid) (P)
Cholesterol (C)
highly non polar molecules
Rank the melting points of the following compounds.
a) H3C-CH2-O-CH3
b)H3C-C=O-NH2
c)H2N-C=O-NH2
d)H3C-(CH2)3-CH3
e)H3C-CH2-CH=O - CORRECT ANSWERS c > b > e > a > d
Thermal energy is added in overcome the intermolecular forces holding molecules together.
The higher those forces, the more the T must be raised to overcome those forces. The strongest
intermolecular forces would be ionic - but none of these molecules are charged. The next
strongest type of intermolecular force would be H bonds. Both (b) and (c) can hydrogen bond -
but (c) can to a greater extent. Next, we look for permanent dipoles - like (a) and (e). In this
, BCH EXAM 1 QUESTIONS AND ANSWERS NEWEST
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case, (e) has a stronger dipole and would therefore have a higher melting point. The weakest
forces are London dispersion - as would be true for (d)
What is the conjugate base of the weak acid H3BO3?
A) BO33-
B) HBO32-
C) H2BO3- - CORRECT ANSWERS c
Which of the following would be the strongest acid?
A) Citrate, pK 4.76
B) Succinic acid, pK 4.21
C) Succinate, pK 5.64
D) Citric acid, pK 3.13
E) Formic acid, pK 3.75 - CORRECT ANSWERS d
What is the pH of a solution of 1.0 x 10-9 M HCl? Express answer as a whole number (no
decimals). - CORRECT ANSWERS The HCl is a strong acid and dissociates completely.
This means that the concentration of hydrogen ions contributed by the HCl is 1.0 x 10-9 M. But
the concentration of the hydrogen ions contributed by the dissociation of water is 100-fold
greater than this: 1.0 x 10-7 M. The concentration of the hydrogen ions contributed by the HCl
is negligible in comparison. Therefore, the pH of the solution is equal to 7.0. Note that this
demonstrates that water, itself, is a buffer! From H2O: 1 x 10-7 M
From HCl: 1 x 10-9 M or 0.01 x 10-7 M
Sum: 1.01 x 10-7 M
