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1.
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In an operon, what is the operator?
a. | sequence of DNA to which RNA polymerase binds to initiate
transcription | b. | regulatory gene that produces a repressor protein | c. | small molecule that
inactivates a repressor protein | d. | sequence of DNA that serves as an “on/off
switch” by controlling access of RNA polymerase to the gene(s) of
interest |
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2.
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What is the role of a repressor protein?
a. | binds to the operator and prevents transcription by RNA
polymerase | b. | blocks the transcription of mutated DNA sequences | c. | transcribes the
genes for proteins that block biochemical pathways | d. | binds to RNA polymerase and prevents
transcription |
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3.
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A corepressor
a. | is a molecule that interacts with a protein to switch off an
operon. | b. | is a molecule that interacts with RNA polymerase to prevent
transcription. | c. | is a molecule that binds to an operon to switch off
transcription. | d. | allows transcription to take place when it binds to a regulatory
protein. |
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4.
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In a repressible operon,
a. | transcription is stimulated directly by the regulatory protein. | c. | transcription is
usually on, but can be prevented by the binding of a molecule to a
protein. | b. | RNA polymerase will not bind to the DNA unless a regulatory protein is
present. | d. | transcription is
usually off, but can be initiated by the binding of a molecule to a
protein. |
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