GCU BIO 181 FINAL EXAM (EXAM 4)
Questions and Correct Answers (Verified
Answers) | New 2026/27 Update | Graded A+
The tryptophan operon is a repressible operon that is: - ANSWERS Turned off
whenever tryptophan is added to the growth medium.
The lactose operon is likely to be transcribed when: - ANSWERS The cyclic
AMP and lactose levels are both high within the cell.
For a repressible operon to be transcribed, which of the following must occur? -
ANSWERS RNA polymerase must bind to the promoter, and the repressor
must be inactive.
Which of the following, when taken up by the cell, binds to the repressor so that
the repressor no longer binds to the operator? - ANSWERS Inducer
What is a promoter? - ANSWERS Sequence where the RNA polymerase binds
and begins transcription. It is upstream of the sequence encoding the protein
Which of the following is a protein produced by a regulatory gene? - ANSWERS
Repressor
What is a corepressor? - ANSWERS A small molecule that combines with and
activates a repressor produced by a regular gene
, What is an operator? - ANSWERS A regulatory sequence that a repressor can
bind to
What is a regulatory gene? - ANSWERS Genes that encode a protein involved
in regulation of gene expression
What has to happen for a gene to be transcribed? - ANSWERS RNA
polymerase, which makes new RNA molecules from a DNA template, must attach
to the DNA of the gene.
In eukaryotes, general transcription factors: - ANSWERS Bind to other proteins
or to a sequence element within the promoter called the TATA box.
What is a TATA box? - ANSWERS DNA sequence that indicates where a genetic
sequence can be read and decoded
Two potential devices that eukaryotic cells use to regulate transcription are -
ANSWERS DNA methylation and histone modification. (epigenetic
phenomena)
Why are viruses obligate parasites? - ANSWERS They cannot reproduce
outside of the host cell
Which characteristic is common to all viruses? - ANSWERS A genome (nucleic
acid) enclosed in a protein capsid
Questions and Correct Answers (Verified
Answers) | New 2026/27 Update | Graded A+
The tryptophan operon is a repressible operon that is: - ANSWERS Turned off
whenever tryptophan is added to the growth medium.
The lactose operon is likely to be transcribed when: - ANSWERS The cyclic
AMP and lactose levels are both high within the cell.
For a repressible operon to be transcribed, which of the following must occur? -
ANSWERS RNA polymerase must bind to the promoter, and the repressor
must be inactive.
Which of the following, when taken up by the cell, binds to the repressor so that
the repressor no longer binds to the operator? - ANSWERS Inducer
What is a promoter? - ANSWERS Sequence where the RNA polymerase binds
and begins transcription. It is upstream of the sequence encoding the protein
Which of the following is a protein produced by a regulatory gene? - ANSWERS
Repressor
What is a corepressor? - ANSWERS A small molecule that combines with and
activates a repressor produced by a regular gene
, What is an operator? - ANSWERS A regulatory sequence that a repressor can
bind to
What is a regulatory gene? - ANSWERS Genes that encode a protein involved
in regulation of gene expression
What has to happen for a gene to be transcribed? - ANSWERS RNA
polymerase, which makes new RNA molecules from a DNA template, must attach
to the DNA of the gene.
In eukaryotes, general transcription factors: - ANSWERS Bind to other proteins
or to a sequence element within the promoter called the TATA box.
What is a TATA box? - ANSWERS DNA sequence that indicates where a genetic
sequence can be read and decoded
Two potential devices that eukaryotic cells use to regulate transcription are -
ANSWERS DNA methylation and histone modification. (epigenetic
phenomena)
Why are viruses obligate parasites? - ANSWERS They cannot reproduce
outside of the host cell
Which characteristic is common to all viruses? - ANSWERS A genome (nucleic
acid) enclosed in a protein capsid
