BIO 340 Exam 4
Questions and
Complete Solutions
Graded A+
Denning [Date] [Course title]
, Lactose is an inducer of the lac operon. - Correct Ans: True
What would be the effect of a mutation in the lacI gene that prevented the repressor from binding to
lactose? - Correct Ans: The lac Z, Y, and A genes would not be expressed.
What is the role of glucose in catabolite repression? - Correct Ans: It decreases the levels of cAMP in the
cell, repressing transcription from the lac operon.
Which of the following mutations could lead to constitutive expression of the genes of the lac operon? -
Correct Ans: A mutation in the operator sequence
Which of the following best describes the biological role of the lac operon? - Correct Ans: It ensures that
a cell dedicates resources to the production of enzymes involved in lactose metabolism only when
lactose is available in the environment.
Submit
The placement of the operator sequence between the promotor and the structural genes is critical to
the proper function of the lac operon. - Correct Ans: True
Under the system of genetic control of the tryptophan operon, ________. - Correct Ans: when there is
no tryptophan in the medium, transcription of the trp operon occurs at high levels
Which of the following occurs as a result of an abundance of tryptophan in E. coli? - Correct Ans: The 5
trp genes (TrpA - TrpE) are not transcribed.
Which of the following features of the trp operon is likely least essential to the process of attenuation? -
Correct Ans: The order of the structural genes, E, D, C, B, A
Attenuator systems such as the one described for regulation of tryptophan synthesis would be just as
likely to occur in eukaryotes as in prokaryotes. - Correct Ans: False
Chromatin remodeling - Correct Ans: refers to changes in DNA/chromosome structure that can
influence overall gene output.
Questions and
Complete Solutions
Graded A+
Denning [Date] [Course title]
, Lactose is an inducer of the lac operon. - Correct Ans: True
What would be the effect of a mutation in the lacI gene that prevented the repressor from binding to
lactose? - Correct Ans: The lac Z, Y, and A genes would not be expressed.
What is the role of glucose in catabolite repression? - Correct Ans: It decreases the levels of cAMP in the
cell, repressing transcription from the lac operon.
Which of the following mutations could lead to constitutive expression of the genes of the lac operon? -
Correct Ans: A mutation in the operator sequence
Which of the following best describes the biological role of the lac operon? - Correct Ans: It ensures that
a cell dedicates resources to the production of enzymes involved in lactose metabolism only when
lactose is available in the environment.
Submit
The placement of the operator sequence between the promotor and the structural genes is critical to
the proper function of the lac operon. - Correct Ans: True
Under the system of genetic control of the tryptophan operon, ________. - Correct Ans: when there is
no tryptophan in the medium, transcription of the trp operon occurs at high levels
Which of the following occurs as a result of an abundance of tryptophan in E. coli? - Correct Ans: The 5
trp genes (TrpA - TrpE) are not transcribed.
Which of the following features of the trp operon is likely least essential to the process of attenuation? -
Correct Ans: The order of the structural genes, E, D, C, B, A
Attenuator systems such as the one described for regulation of tryptophan synthesis would be just as
likely to occur in eukaryotes as in prokaryotes. - Correct Ans: False
Chromatin remodeling - Correct Ans: refers to changes in DNA/chromosome structure that can
influence overall gene output.
