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18 Cards in this Set
- Front
- Back
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How are ribosomal RNAs made? what are the subunits? |
they are synthesized in the nucleolus as pre-rRNA and then are cleaved by RNases to form the final products. they are made by poly I the subunits are 28S, 5.8S and, 18S. |
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Describe the transcription initiation complex of RNA pol I in euk. |
there are 2 main elements involved an upstream element and a core element. there are a bunch of different upstream activating factors that bind to the upstream element including histone subunits (3 and 4) as well as core factors like Tata binding protein (TBP). These all recruit the Pol 1 to come and bind at the promoter site. |
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what is different about the recognition methods of the transcription start sites used by prok and euk.? |
prok have the polymerase with an sigma subunit that recognizes the operators.
euk pol don't have that. they need a bunch of other protein factors to come and basically put out a beacon telling the pol 1 to come there. |
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what does euk pol 3 transcribe proteins for? |
for tRNA and 5S rRNA
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Describe the transcription initiation complex of RNA pol III in euk.
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for the tRNA, we have Transcription factor (TF3B) that contains the TATA Box binding motif. we also have TF3C. these proteins bind to the dna and also recruit/bind to pol 3
for 5S rRNA, we have theTF3B TF3C and TF3A doing the job of recruiting pol 3
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what kind of processing does euk. tRNA undergo after being made? |
RNase P cleaves a 16 NT seq at the 5' end. 14 NT intron is removed from the anticodon region. uracil residues at the 3' end are replaced by CCA seq. found in all mature tRNAs a lot of bases are converted into modified bases. |
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what do most pol 2 transcripts begin with |
75% of time purine 25% time pyrimidine. |
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Describe the transcription initiation complex of RNA pol II in euk. |
similar to the other ones, transcription factors need to recruit Pol 2 to the DNA. there is a TATA box where TBP binds to and bends the DNA.this allows other transcription factors to bind and create the preinitiation complex. |
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what does Pol 2 synthesize? what is different about pol 2 |
it synthesizes mRNA and some snRNA. along with TF2F, Pol2 has a subunit called Carboxyl terminal domain (CTD) which plays a crucial role in the elongation of polymerase |
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what important transcription factors are present in the preinitiation complex of pol II |
it has TF2E which has helicase activity. it has TF2H which has kinase activity which phosphorylates the CTD. |
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what kind of control elements are present in the euk gene that can regulate transcrip |
there are promoter-proximal elements (which are close to the start of transcription sites) and enhancers which are generally far away. |
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what are some examples of promoter-proximal elements? what do they bind to? what role do they play? |
SP1 which binds to GC box CTF which binds to CAAT box. they generally create a space where the enhancer proteins along with the dna can loop over and bind to/have protein interactions with the pol II |
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what roles do mediators play in the process of transcriptional regulation in euk.? |
they serve as a scaffolding that brings farther away sequences closer to the pol in order to be affected. the mediators bind to the promoter proximal regions and other transcriptional factors. |
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how do hormones act as transcription factors in the nucleus for euk.? |
lipid soluble hormones (steroid hormones) are able to get into the cell and bind to a ligand binding domain. which knocks of the inhibitor. these then enter into the nucleus and bind to the DNA and dimerize. |
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what are zinc finger motifs? where are they located? |
These allows the activated receptor to bind to the DNA and regulate the expression of genes. they are 4 AAs interacting with a divalent zn molecule. they are located on the DNA binding domains of the nuclear receptors. |
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describe the role of transcription factor CREB and how it works |
cAMP activates PKA which have 2 catalytic and 2 regulatory domains. the 2 catalytic domains split from the regulatory domains when cAMP binds. these subunits translocate into the nucleus and activate CREB by phosphorylating it. this dimerizes and binds to DNA . this then initiates transcription factors for cAMP response element. |
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What causes Rubinstein-Taybi syndrome? what happens? |
it is as a result of CBP (CREB binding protein) and it leads to developmental abnormalities. facial alterations, abnormal digits, heart failure, mental insufficiencies and death |
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what AAs do histone acetyl transferases and deacetyl transferases usually act on? |
lysine. |
