ECU Biology 1100 CH.17 Review Questions and Correct Answers
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Course
ECU BIO 1100
Institution
ECU BIO 1100
The first step in converting genetic information into proteins is transcription
Transcription Synthesis of an mrna version of the instructions stored in DNA
Template strand RNA polymerase performs this synthesis by transcribing only one strand of DNA
The other DNA strand is called non-template, ...
ECU Biology 1100 CH.17 Review
Questions and Correct Answers
The first step in converting genetic information into proteins is ✅transcription
Transcription ✅Synthesis of an mrna version of the instructions stored in DNA
Template strand ✅RNA polymerase performs this synthesis by transcribing only one
strand of DNA
The other DNA strand is called ✅non-template, or coding strand
-Matches the sequence of the mrna
- expect u are where the T's are
RNA polymerase do not require a ✅primer
Phosphodietser linage is formed by ✅RNA polymerase after case pairing occurs
Initiation ✅1st phase of transcription
RNA polymerase cannot initiate ✅transcription on
its own
Prokaryotic RNA polymerase ✅holoenzyme
Sigma ✅protein subunit
- must first bind to the polymerase
- guiding RNA polymerase to specific promoter sequneces
- on the DNA template strand.
Holoenzyme ✅- made up of the core enzyme and a sigma subunit
- has ability to synthesize RNA
Sigma acts as a ✅regulatory factor
Bacterial promoters ✅Are comprised of 4050 base pairs
Bacterial promoters have 2 key regions ✅-10 box and -35 box
-10 box ✅- Is found 10 bases upstream from the transcription start site (the 1 site)
- Consists of the sequence TATAAT
, -35 box ✅Is 35 bases upstream from the 1 site
Consists of the sequence TTGACA
Sigma factors bind to the ✅-35 and -10 boxes
- in the promoter
Transcription begins ✅- When sigma, as part of the holoenzyme complex
- Binds to the -35 and -10 boxes
Sigma, and not RNA polymerase, makes ✅- The initial contact with DNA that starts
transcription
- Supporting the hypothesis that sigma is a regulatory protein
Most bacteria have several types of sigma proteins ✅Each type allows RNA
polymerase to bind to a different type of promoter therefore a different kind of gene
Sigma opens the DNA double helix ✅The template strand is threaded through the
RNA polymerase active site
Sigma dissociates from the core enzyme ✅Once the initiation phase of transcription is
completed
Elongation phase of transcription ✅- RNA polymerase moves along the DNA template
- Synthesizes RNA in the 5 3 direction
Termination phase ✅- RNA polymerase transcribes a transcription
termination signal
- In the DNA template into RNA
In bacteria the transcription termination signal ✅- Codes for RNA that forms a hairpin
structure
- Causes the RNA polymerase to separate from the RNA transcript and thus to end
transcription
Eukaryotes have A much more diverse and complex series of promoters than
✅prokaryotes
Eukaryotic promoters ✅A unique sequence called the TATA box
Centered about 30 base pairs upstream of the 1
As with bacteria, the RNA polymerase does not bind directly to the ✅promoter
Basal transcription factors ✅Bind to the DNA promoter
Initiate transcription
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