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24 Cards in this Set
- Front
- Back
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What is another name for RNA polymerases? Why is it called that?
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DNA-dependent RNA polymerases. This is because the polymerase requires a DNA template in order for it to transcribe a strand of RNA.
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What enzyme is responsible for transcribing RNA in both prokaryotic and eukaryotic cells?
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RNA polymerase
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The site on the DNA to which an RNA polymerase binds prior to initiating transcription.
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Promoter
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In what direction does an RNA polymerase move along the template DNA?
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3'->5'
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In what direction does a newly synthesized RNA chain grow?
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5'->3'
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What does it mean the an RNA polymerase must be processive?
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It must remain attached to the DNA template over long stretches.
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In what form do nucleotides enter the polymerization reaction?
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As trinucleotide precursors.
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The polymerization reaction is driven forward by the hydrolysis of _______.
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pyrophosphate (PPi->2Pi)
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What is the only type of RNA polymerase found in prokaryotes?
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A core enzyme formed by five associating subunits.
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What are the two enzymatic activities of RNA polymerase?
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-digestion of incorrect nucleotides
-polymerization |
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In the absence of _______, the core enzyme cannot associate with DNA at specific initiation sites.
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sigma factor
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The attachment of a sigma factor to the core enzyme increases its affinity to _______ and decreases its affinity to _______.
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-promoter sites
-the DNA |
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What are the two conserved regions of DNA in prokaryotes?
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- (-35 element)/consensus sequence
- Pribnow Box |
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What is the amino acid sequence for the consensus sequence?
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TTGACA
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What is the amino acid sequence for the Pribnow Box?
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TATAAT
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What are two ways of transcription termination that can occur in bacteria?
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-rho factor dissociates the RNA and DNA
-terminator sequence |
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What are the three types of RNA polymerases found in eukaryotic cells?
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-RNA polymerase I, II, and III
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What types of RNAs are synthesized by RNA polymerase I?
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Most rRNAs:
- larger rRNAs -28S -18S 5.8S |
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What types of RNAs are synthesized by RNA polymerase II?
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mRNAs:
-most small nuclear RNAs (snRNAs and snoRNAs) -most microRNAs -telomerase RNAs |
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What types of RNAs are synthesized by RNA polymerase III?
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-tRNAs
-5S RNA -U6 snRNA |
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_______ regulate the activity of RNA polymerases in eukaryotic cells.
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Transcription Factors
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The initial RNA molecule synthesized.
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primary transcript (pre-RNA)
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DNA segment corresponding to a primary transcript.
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Transcription Unit
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Which RNA polymerases in eukaryotes are
most sensitive to toxin second most and least? |
Most - RNAII
2nd - RNA III Least - RNAI |
