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30 Cards in this Set
- Front
- Back
All RNA is synthesized on a template of _____.
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...DNA.
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What were the 3 types of RNA we studied?
(abbreviation and name) |
rRNA = Ribosomal RNA
tRNA = Transfer RNA mRNA = Messenger RNA |
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2 synonymous terms for the "template" DNA strand are:
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1) antisense
2) non-coding |
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2 synonymous terms for the "non-template" DNA strand are:
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1) sense
2) coding |
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2 synonymous terms for the "antisense" DNA strand are:
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1) template strand
2) non-coding |
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2 synonymous terms for the "non-coding" DNA strand are:
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1) antisense
2) template strand |
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2 synonymous terms for the "sense" DNA strand are:
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1) coding
2) non-template |
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2 synonymous terms for the "coding" DNA strand are:
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1) sense
2) non-template |
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The E. coli RNAp holoenzyme is labeled with the subunit composition:
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α₂ββ'ωσ
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The E. coli RNAp core enzyme is labeled with the subunit composition:
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α₂ββ'ω
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DNA sequences that signal transcriptional start sites are called...
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...promoters.
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By convention, promoter sequences show the (non-sense/sense) strand.
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...sense...
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Sequence of Sense strand for promoters:
The Initiation site is labeled with the number _____. |
+1
|
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Sequence of Sense strand for promoters:
The type of nucleotide that is found at the Initiation site is usually... |
...purine. (A or G)
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Sequence of Sense strand for promoters:
The Pribnow Box is represented by the conserved nucleotide sequence... |
...TATAAT
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Sequence of Sense strand for promoters:
The Pribnow Box is labeled with the number _____. |
-10
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Describe the process of the E. coli RNAp holoenzyme recognizing and attaching to DNA.
(5 steps) |
1) σ recognizes the promoter
2) Holoenzyme (α₂ββ'ωσ) loosely associates with DNA 3) Moves along until it finds promoter sequence 4) Opens up DNA 5) Initiates transcription and loses σ |
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What are 2 common features that termination sequences of many E. coli genes share?
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1) A series of 4-10 consecutive A-T base pairs.
- A's are on the *template* strand. 2) G + C rich sequence that immediately precedes the series of A-T's. |
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The transcription of a termination sequence forms what type of structure?
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stem-loop
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What are the 2 methods by which transcription can be terminated?
Describe each briefly. |
1) Termination sequence
- stem-loop slows down RNAp - weak base pairing - rewinding DNA pushes RNA off the template 2) Rho-factor dependent termination - rho protein - recognizes sequence on nascent RNA - unwinds the RNA-DNA complex |
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True/False:
Once eukaryotic DNA is transcribed to form a strand of mRNA, the mRNA can be used immediately as a template to synthesize proteins. |
FALSE.
The mRNA of eukaryotes has to undergo post-transcriptional processing before it can be used. |
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The 3 main types of processing the eukaryotic mRNA undergoes are:
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1) 5' capping
2) Polyadenylation (i.e. poly-A tail) 3) Splicing |
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Post-transcriptional modification of mRNA:
Describe the "5' cap" and how it is linked. |
A structure consisting of a 7-methylguanosine (m⁷G) residue joined to the transcripts initial (5') nucleotide via a 5'-5' triphosphate bridge.
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Post-transcriptional modification of mRNA:
Describe the 3 steps involved in "capping" |
1) Removal of the 5' phosphate
2) Addition of guanine mono-phosphate. 3) Methylation of guanine at N7. |
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Post-transcriptional modification of mRNA:
Describe the 2 step process of "poly-A addition". |
1) Cleavage of 15-25 nucleotides 3' to AAUAAA sequence
2) Template independent addition of ~250 A to 3' end of RNA |
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Post-transcriptional modification of mRNA:
What is the function(s) of the "poly-A tail"? |
Gives stability.
Acts as a timer for degredation. |
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Post-transcriptional modification of mRNA:
What happen during splicing? |
Splicing is the removal of non-coding sequences of mRNA.
The introns (non-coding regions) are removed and the exons (coding regions) are spliced together. |
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Post-transcriptional modification of mRNA:
Which are bigger, introns or exons? |
Introns are around ~4-6 times larger than exons.
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Post-transcriptional modification of mRNA:
preRNA (RNA that has yet to be modified) is also known as what? |
heterogeneous nuclear RNA (hnRNA)
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True/False:
hnRNA can be used to synthesize proteins! |
FALSE
hnRNA has not yet been processed. |