Biology 1002B Study Guide - Stem-Loop, Start Codon, Riboswitch

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Published on 21 Apr 2013
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Types of RNA
mRNA-can pair w/itself, pairs w/rRNA (SD Box and docking), pairs w/DNA
-in the nucleus, leaves the nucleus only to be translated
- it’s structure contains information... so does it’s sequence
-ribo-switch influences translation of mRNA
tRNA- can pair w/itself, pairs w/start codons, help w/ the pairing of anticodons w/codons to make amino
acids, pairs w/DNA
- functions outside the nucleus
rRNA-can pair w/itself, pairs w/mRNA (SD Box)this pairing docks the ribosomes onto the mRNA to
start translation, pairs w/DNA
-functions outside the nucleus
-has enzymatic ability
snRNA- pairs w/mRNA
-functions inside the nucleus
-recognizes splice signals in the mRNA... therefore splice signals must be in the DNA but are only
understood as mRNA by snRNA and snRNPs (protein)
microRNA-pairs w/itself
- it associates with a dicer which cuts the RNA into many pieces which then attract other
proteins which then bind to a single strand of RNA and then pairs w/ mRNA and inhibits
translation/ degrades RNA
all kinds of RNA will pair w/DNA since they are made from DNA in transcription
promoter- regulatory part
-attract the attention of RNA polymerase this binds to the promoter and begins transcription
-understood as DNA
-position AND direction dependent
terminator sequence- regulatory information to stop transcription
- only works after it has been transcribed
- forms a hair-pin loop which knocks off the polymerase
- understood as RNA
start codon- is the first to be translated, it is not the first to be transcribed
-understood as RNA
5’UTR- upstream of the start codon Untranslated regionTHIS IS TRANSCRIBED BUT NOT
TRANSLATED (helps w/the SD box)
stop codon- promotes the binding of release factors and then the ribosome simply falls off
- UAA, UAG, UGA and AUG (tRNA)
-understood as RNA
SD Box- on the mRNA and binds w/ rRNA to dock the ribosome to the mRNA
- understood as RNA
coding region- transcribed and translated
3’UTR- after everything else/downstream, transcribed NOT translated
Proximal promoter region- eukaryotic, acts like CAP in prokaryotes, activators bind here to make the
sequence more stable once transcription factors start piling on after the TBP
(TATA Binding Protein) has bound to the promoter
enhancer- upstream of the promoter, are not transcribed, transcription factors ALSO bind to this to
make the sequence more stable before folding over enhancer= a binding site for activator
-enhances/increases transcription but is NOT transcribed
clipping sequence-eukaryotic, it is transcribed and attracts an RNAse which cuts the message causing
the polymerase to stop transcribing and leaves a free 3’ end to which
polyApolymerase adds a string of adenines AFTER TRANSCRIPTION *there is NO
polyA sequence in the DNA
release factors- protein which binds to the ribosome (IT IS A PROTEINit has no bases so it cannot base
- release factors are always around, but are outcompeted by tRNA until the stop codon
since there are no tRNA which recognize the stop codon
DNAmRNA (binds w/rRNA of the ribosome)tRNAamino acids
ubiquitin- tags protein for degradation by proteosomes
Lac Operon
promoter- there is one promoter for the lacZ and lacy
lacI=lac repressor has it’s own promoter (found upstream of the lac operon)
repressor= DNA binding protein.... binds to operator
allolactose- binds to the repressor and makes it unable to bind to the operator
CAP/cAMP- found just before the operon
-proteins bind here to regulate transcription
-cAMP enables CAP to bind w/DNA and when this happens expression of the lac operon
-transcription increases when CAP bound
Proteins targeted to the E.R
-hormones, antibodies, enzymes (for lysosomes)
Things to remember...
in tRNA (stop codons)
UGA: "U Go Away"
UAA: "U Are Away"
UAG: "U Are Gone"
in DNA (stop codons)
TAG: "They Are Gone"
TAA: "They Are Away"
TGA: "They're Going Away"