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9 Cards in this Set
- Front
- Back
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Draw a picture of bacterial transcription.
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What are the 3 main steps of bacterial transcription?
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1) Initiation
2) Elongation 3) Termination |
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What are the 2 main steps of transcription initiation?
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1) RNAP, containing the σ-factor, slides along DNA to scan for a promoter.
2) Once a promoter is found, DNA begins to unwind at the -10 position. |
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What are the two parts of the transcription promoter in bacteria and where are they?
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1) The TATA box at -10 (TATAAT)
2) TTGACA sequence at -35 |
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In bacterial transcription, what are the 4 steps of elongation?
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1) Transcription bubble forms between the 2 strands of DNA (via unwinding).
2) σ-factor falls off after a few bases because it's no longer needed. 3) RNA is transcribed 5' to 3' as RNAP moves along DNA. 4) The DNA is rewound behind RNAP. |
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About how fast does transcription happen in bacteria? (nucleotides per second)
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25-50 nucleotides per second
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In bacterial transcription, what are the 2 steps of termination?
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1) RNAP reaches a pause sequence.
2) RNAP comes off via rho-dependent or rho-independent termination. |
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Describe rho-independent termination. (3 steps)
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1) RNAP reaches a pause sequence.
2) A hairpin forms in the RNA strand due to GC rich region (it is a palindrome). The RNA folds back on itself due to the strong GC base pairing. The hairpin prevents RNAP from backing up. 3) The GC rich region is followed by an AT rich region which is pulled away from the DNA due to the formation of the hairpin. |
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Describe the two types of transcription regulation.
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1) Negative regulation: a bound repressor inhibits transcription.
2) Positive regulation: a bound activator facitilitates transcription. |
