BCH Exam 2
The burst phase for chymotrypsin hydrolysis of p-nitro phenylacetate is evidence for:
a. General-acid/general base catalysis
b. allosteric activation
c. a covalent intermediate
d. feedback activation
e. rapid-localization solvent pH change - correct answer ✔✔a covalent intermediate
A characteristic feature(s) if the ordered addition mechanism for a bimolecular enzyme reaction is
(choosing from the following)
i. a compulsory binding sequence
ii. a ternary enzyme-substrate complex
iii. conformationally modified enzyme
iv. covalent enzyme-substrate complex
v. the same Michaelis constant for both substrates. - correct answer ✔✔i. a compulsory binding
sequence
ii. a ternary enzyme-substrate complex
Hyperchromicity refers to:
a. fine structure in the absorbance spectrum of nucleic acid
b. spectra shifts due to cation interactions with the phosphodiester backbone of nucleic acids.
c. changes in the ratio of absorbance at 280nm/260nm when the nucoleic acid component of nucleic
acid/protein mixture is increased.
d. enhancement of the absorption accompanying melting of DNA
,e. conversion of DNA from colorless to orange when reacted with certain dye complexes. - correct
answer ✔✔enhancement of the absorption accompanying melting of DNA
Which of the following is most likely to show homotropic cooperativity with aspartate transcarbamylase?
a. glutamic acid
b. asparaginine
c. ATP
d. GTP
e. carbamyl phosphate - correct answer ✔✔carbamyl phosphate
The reaction A->B is known to have a G° = -25kj/mol.deg. What can be predicted about this reaction?
a. The reaction is spontaneous as written under standard conditions.
b. An enzyme or other catalyst is necessary for this reaction to reach equilibrium.
c. The reaction has a fairly high activation energy..
d. The standard state entropy for this reaction must be negative.
e. A large amount of heat must be liberated during reaction. - correct answer ✔✔The reaction is
spontaneous as written under standard conditions.
First order kinetics for enzymatic reaction are obeyed:
a. at one-half maximum velocity
b. when substrate is saturating
c. when [S] = Km
d. When substrate concentration is below the Michaelis constant.
e. at Vmax - correct answer ✔✔When substrate concentration is below the Michaelis constant
Branching of the glycogen molecule is due to the formation of:
, a. alpha 1,4 linkages between glucose units
b. beta 1,4 linkages between glucose units
c. alpha 1,6 linkages between glucose units
d. beta 1,6 linkages between glucose units
e. alternating alpha 1,4 and beta 1,4 linkages between glucose units. - correct answer ✔✔alpha 1,6
linkages between glucose units
Which of the following lipids would you expect to contribute most to increase membrane fluidity?
a. 1 palmitoyl-2-oleoyl-phosphatidyl choline
b. 1,2 palmitoyl-phosphatidyl choline
c. 1,2 oleoyl-phosphatidyl -choline
d. 1,2 linoleyl-phosphatidyl choline
e. 1 palmitoyl-2-stearoyl-phosphatidyl choline - correct answer ✔✔1,2 linoleyl-phosphatidyl choline
Which of the following is an aldose/ketose pair (in that order)?
a. fructose/mannose
b.glucose/mannose
c. glucose/ribose
d. ribose/galactose
e. glyceraldehyde/dihydroxyacetone. - correct answer ✔✔glyceraldehyde/dihydroxyacetone.
Enzymes which act on monosaccharides to change the configuation around a specific carbon atom are
called:
a. transferases
b. reductases
The burst phase for chymotrypsin hydrolysis of p-nitro phenylacetate is evidence for:
a. General-acid/general base catalysis
b. allosteric activation
c. a covalent intermediate
d. feedback activation
e. rapid-localization solvent pH change - correct answer ✔✔a covalent intermediate
A characteristic feature(s) if the ordered addition mechanism for a bimolecular enzyme reaction is
(choosing from the following)
i. a compulsory binding sequence
ii. a ternary enzyme-substrate complex
iii. conformationally modified enzyme
iv. covalent enzyme-substrate complex
v. the same Michaelis constant for both substrates. - correct answer ✔✔i. a compulsory binding
sequence
ii. a ternary enzyme-substrate complex
Hyperchromicity refers to:
a. fine structure in the absorbance spectrum of nucleic acid
b. spectra shifts due to cation interactions with the phosphodiester backbone of nucleic acids.
c. changes in the ratio of absorbance at 280nm/260nm when the nucoleic acid component of nucleic
acid/protein mixture is increased.
d. enhancement of the absorption accompanying melting of DNA
,e. conversion of DNA from colorless to orange when reacted with certain dye complexes. - correct
answer ✔✔enhancement of the absorption accompanying melting of DNA
Which of the following is most likely to show homotropic cooperativity with aspartate transcarbamylase?
a. glutamic acid
b. asparaginine
c. ATP
d. GTP
e. carbamyl phosphate - correct answer ✔✔carbamyl phosphate
The reaction A->B is known to have a G° = -25kj/mol.deg. What can be predicted about this reaction?
a. The reaction is spontaneous as written under standard conditions.
b. An enzyme or other catalyst is necessary for this reaction to reach equilibrium.
c. The reaction has a fairly high activation energy..
d. The standard state entropy for this reaction must be negative.
e. A large amount of heat must be liberated during reaction. - correct answer ✔✔The reaction is
spontaneous as written under standard conditions.
First order kinetics for enzymatic reaction are obeyed:
a. at one-half maximum velocity
b. when substrate is saturating
c. when [S] = Km
d. When substrate concentration is below the Michaelis constant.
e. at Vmax - correct answer ✔✔When substrate concentration is below the Michaelis constant
Branching of the glycogen molecule is due to the formation of:
, a. alpha 1,4 linkages between glucose units
b. beta 1,4 linkages between glucose units
c. alpha 1,6 linkages between glucose units
d. beta 1,6 linkages between glucose units
e. alternating alpha 1,4 and beta 1,4 linkages between glucose units. - correct answer ✔✔alpha 1,6
linkages between glucose units
Which of the following lipids would you expect to contribute most to increase membrane fluidity?
a. 1 palmitoyl-2-oleoyl-phosphatidyl choline
b. 1,2 palmitoyl-phosphatidyl choline
c. 1,2 oleoyl-phosphatidyl -choline
d. 1,2 linoleyl-phosphatidyl choline
e. 1 palmitoyl-2-stearoyl-phosphatidyl choline - correct answer ✔✔1,2 linoleyl-phosphatidyl choline
Which of the following is an aldose/ketose pair (in that order)?
a. fructose/mannose
b.glucose/mannose
c. glucose/ribose
d. ribose/galactose
e. glyceraldehyde/dihydroxyacetone. - correct answer ✔✔glyceraldehyde/dihydroxyacetone.
Enzymes which act on monosaccharides to change the configuation around a specific carbon atom are
called:
a. transferases
b. reductases
