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Transcrip Translate
Question | Answer |
---|---|
What types of RNA polymerases are there in eukaryotes? | 3 - RMiT - ribosomal, messenger, transfer |
What is the holoenzyme? | core enzyme of 5 subunits plus sigma facotr, used for initiation of transcription. |
What is the recognition region for eukaryotic promotors called? | TATA box - AT rich. |
When does Euk transcrip start? | when TFIID (Transcription Factor for Polymerase II + D (sigma factor)) binds to TATA via the TATA Binding Protein TBP. ` |
What does the pre-initiation complex consist of? | TFIID bound to TATA box, TFIIB, RNApolII, TFIIF, TFIIE, TFIIH, CTD, other factors. |
What finally activated transcription? | TFIIH with helicase activity unwinds DNA at TATA box. with kinase activity it phosphorylates the CTD tail at Ser-5. |
What is the mediator complex comprised of? | Mediator, chromatin remodeling complex, histone-modifying enzyme, transcription facotr. |
Why is the C terminal domain important? | the CTD is a key regulatory region of RNApolII. Consists of 52 tandem repeats of 7 AA motif with Ser at pos 2 and 5. The phosphorylation of Ser5 affects the conformation and activity of RNApolII, releasing it to begin transcription. |
Where are proteins sourced for the emerging mRNA strand from? | From the capping proteins that bind to CTD when Ser5 is phosphorylated. |
What is added to 5' end of newly formed pre-mRNA? | 7-methylguanosine. |
What happens when Ser2 is phosphorylated? | other proteins bind to CTD such as splicing factors. |
What are the things that ride on the CTD and recognise specific sequence motif for termination? | CPSF and CstF (Cleavage Polyadenylation Specificity Factor & Cleavage Stimulation Factor). |
To which end are polyAs added? | 3'. |
Which sequences indicated intron removal? | 5' end AGGURAGU and CTRAYY and 3' end YYYYYYYYNCAGG. I.e. consensus sequences. |
What is the spliceosome made up of? | of snRNPs - complex of both RNA and proteins, where the RNA is snRNA. |
Why does splicing need to be precise? | if not in correct reading frame, STOP codons are common. Might potentially truncate the protein. |
What is the wobble position? | First two nucleotides are correct, will do same protein. Third spot in codon is wobble. |
Which enzyme covalently attaches each AA to its tRNAs by a specific enzyme? | aminoacyl-tRNA synthetase. |
What are ribosomes composed of? | rRNAs and ribosomal proteins that catalyses the synthesis of protein using info provided by mRNA. |