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Cell bio-
RNA: structure , synthesis and processing
| Question | Answer | |
|---|---|---|
| RNA is the final product of some genes. (T/F) | T | |
| which is true ? RNA has Enzymatic activity RNA can reproduce itself | both | |
| Unlike DNA the sugar of the RNA backbone is | ribose, | |
| ribose differs from the deoxyribose of DNA by the presence of | a OH- group on carbon 2 of the ribose. | |
| what is different when comparing base- pairing in RNA and DNA | some unusual base pairings occur in RNA ; G-U / U-U | |
| Although RNA is generally single stranded, it forms three dimensional structures through | pairing of the nucleotide bases and folding. | |
| Bases pair between RNA molecules and within the same RNA molecule form | a double helix | |
| Base pair between RNA and DNA form | RNA-DNA hybrid structures. | |
| Base Pairing Forms Tertiary Structures from Single Stranded RNA (T/F ) | T | |
| long sequences of RNA that regulate specific functions in cells. | Long non-coding RNA | |
| tRNA :: Amino acids specified by the anticodons are covalently attached (by enzymes known as aminoacyl tRNA synthetases) to | a conserved sequence (5’-CCA-3’) at the 3’ end (short arm) | |
| How is tRNA charged with AA | Aminoacyl tRNA synthetase | |
| a single aminoacyl tRNA synthetase will catalyze the reaction between a given amino acid and all of the tRNA with anticodons for the given amino acid. (T/F) | T | |
| that if an amino acid is chemically modified after it is bound to its tRNA the modified amino acid will not be inserted into the protein. | False | |
| kinds of rRNA in eukaryotes and prokaryotes | eukaryotes :: 18S, 28S , 5.8S , 5.0S prokaryotes :: 16S , 23S and 5S | |
| the only RNA that encodes proteins | mRNA | |
| Most eukaryotic mRNA have | a long sequence of adenines at their 3’ end called | a “polyA tail”. |
| Transcription is carried out by enzymes called | RNA polymerase. | |
| RNA is synthesized in the(direction ) | 5’-3’ direction | |
| RNA polymerase catalyzes linkage formation with ribose and not deoxyribose.(T/F) | T | |
| RNA polymerase does not require | a primer | |
| RNA polymerase is not as precise DNA polymerase (one mistake every 104 bases.) (T/F) | T | |
| transcription unit. is | The transcribed segment of DNA | |
| Transcription requires the opening and unwinding of a region of DNA. Enzymatic activities of the | RNA polymerase protein subunits carry out this function (e.g., chromatin remodeling). | |
| Signals encoded in DNA determine the boundary of genes (T/F) | t ; and regulate where transcription begins and ends. | |
| Prokaryotic RNA polymerases :: core enzyme consists of 4 protein subunits | 2 called α, 1 called β, 1 called β‘ | |
| Prokaryotic RNA polymerases :: The Core enzyme does not contain all enzymatic functions needed for RNA synthesis (t/F) and Cannot bind to DNA promotor (t/F) | F ; T ; A fifth subunit, called ___ is needed for binding promoters and initiation | sigma (σ) factor :: Holoenzyme = core (α2ββ‘) plus a σ factor |
| Either strand of DNA can serve as the template for transcription . | T | |
| ensures the proper location and orientation of the RNA polymerase. | promoter | |
| Since RNA polymerease synthesizes RNA by adding nucleotides (to the 3’ end of the transcript) using the 5’ position of the incoming nucleotide, the 5’ to 3’ orientation -- determines which strand will serve as the template. | of the promoter | |
| Promoters are asymmetrical | T | |
| terminator of transcription can be | factor independent or factor dependent | |
| In termination of transcription ____ involves encountering sequences that can form a stem-loop hairpin structure followed immediately by a series of U residues in the growing RNA chain | Factor independent (aka rho-independent) | |
| In termination of transcription factor dependent(rho-dependent ) | involves the action of a protein known as rho which can become associated with the transcriptional apparatus via recognition of certain sequences in the growing transcript (it does not require the “hairpin-U’s” structure) | |
| what are the 3 types of eukaryotic RNA polymerases that transcribe specific types of genes | RNA pol I , II, III | Rna pol I -- for rRNAs RNA pol II - mRNA and snRNAs RNA pol iii - tRNAs, 5S rRNA and some snRNAs |
| general transcription factors | proteins to initiate and complete the transcription process | they position the pol at the start of a gene |
| The promoter in eukaryotes is | a sequence of nucleotide bases that constitutes | a recognition site for binding of the RNA polymerase-TF complex. |
| In eukaryotic cells many promoters contain | an alternating repeat of T’s and A’s | called the TATA box |
| The TATA sequence is typically located | 25 bases upstream of the | transcription start site (TSS). |
| Other promoters contain regions rich in C and G | T | |
| In eukaryotic cells transcription is initiated by | the binding of TATA binding protein (TBP) to | the TATA sequence. |
| RNA is a linear polymer that can form 3D structures as a result of base paring and folding (allows Enz activity). | T | |
| eukaryotic post transcriptional processing | 5' cap with methylguanosine ; introl splicing ; poly a tail at 3' |
Created by:
jemalk
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