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| is a specially altered nucleotide on the 5' end of precursor messenger RNA and some other primary RNA transcripts as found in eukaryotes. This is vital to creating mature messenger RNA, which is then able to undergo translation. Capping ensures the messenger RNA's stability while it undergoes translation in the process of protein synth. (highly regulated in the cell nucleus.) Is called m7G cause the guanosine is methylated on the 7 position after capping by a methyl transferase. |
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| is a process by which the exons of the RNA produced by transcription of a gene (a primary gene transcript or pre-mRNA) are reconnected in multiple ways during RNA splicing. The resulting different mRNAs may be translated into different protein isoforms; thus a single gene may code for multiple proteins. |
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| the carboxyl terminus of a protein. |
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| cleavage/polyadenylation site |
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| is an endoribonuclease in the RNase III family that cleaves double stranded RNA and pre-microRNA into short double stranded RNA fragments (siRNA). They catalyze the the first step in RNA interference pathway and initiates formation of the RNA induced silencing complex. |
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| is a nucleic acid sequence that is represented in the mature form of an RNA molecule either after portions of a precursor RNA (introns) have been removed by cis-splicing or when two or more precursor RNA molecules have been ligated by trans-splicing |
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| has major influences on translation surveillance and localization of the spliced mRNA. It is deposited on mRNA during splicing and is then transported into the cytoplasm. It is believed to provide a a position specific memory of the splicing event. Has a stable heterotetramer core (serves as binding platform) |
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| expressed sequence tag (EST) |
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| is a short sub-sequence of a transcribed cDNA sequence. They may be used to identify gene discovery and gene sequence determination. |
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| heterogeneous nuclear RNA (hnRNA) |
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| also known as pre-mRNA- is an immature single strand of mRNA. Synthed from a DNA template in the cell nucleus by transcription. Also includes nuclear RNA transcripts that do not end up as cytoplasmic mRNA |
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| is any nucleotide sequence within a gene that is removed by RNA splicing to generate the final mature RNA product of a gene. |
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| is a splicing mechanism where splicesomes create a lariat like structure to remove introns, and join exons. |
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| are short RNA molecules (22 nuc. long). Theses are post transcriptional regulators that bind to complementary sequences on target mRNA transcripts, usually resulting in translation repression or gene silencing. |
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| it creates the 5' cap, and is part of the transferase family |
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| is a cellular mechanism of mRNA surveillance that functions to detect nonsense mutations and prevent the expression of truncated or erroneous proteins. Large intron regions increase the probability of stop codons somewhere within the open reading frame. This is a medium for degrading aberrant mRNA. |
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| it is conducted to identify the genes that are being transcribed at a certain time. Cell nuclei are isolated rapidly, and incubated with labelled nucleotides, and then the results are hybridized to a blot which is exposed to film. You can add things such as a-amanitin to show different effects. (Shows transcription rates) |
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| is an enzyme that catalyzes the reaction of ATP and RNA to diphosphate and RNA with an extra adenosine nucleotide at its 3' end-its a transferase- it creates the poly a tail. |
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| is the addition of multiple adenosine monophosphates (lots of A bases) It is important for nuclear export, translation and stability of mRNA. It is shortened over time, and when it is short enough it is enzymatically degraded. |
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| is the addition of a poly(A) tail to an RNA molecule. The poly (A) tail consists of multiple adenosine monophosphates- (long stretch of A bases.) -The 3' most segment of the newly made RNA is cleaved of by a set of proteins, which then synth, the poly(A) tail at the 3' end. This is important for nuclear transport, translation and stability. If the poly(A) |
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| the upstream signaling region has the sequence AAUAAA which is highly conserved, down stream is a GU rich region |
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| The poly A tail acts as the binding site for poly E binding protein. THis promotes export from the nucleus and translation, and inhibits degradation. This binds to the tail prior to export, and also recruits poly (A) nuclease (what shortens the poly A tail. |
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| is an immature single strand of mRNA. Is synthed from a DNA template in the cell nucleus by transcription. Comprises the bulk of heterogeneous nuclear RNA. pre-mRNA has not been spliced, or had the 5' cap added, or a poly (a) tail |
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| This is a protein that loads miRNA to proteins |
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| describes the process by which the information content in an RNA molecule is altered through a chemical change in the base makeup. This occurs in the nucleus and cytosol, as well as in mitochondria and plastids. |
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| RNA induced silencing complex (RISC) |
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| is a multiprotein complex that incorporates one strand of a small interfering RNA or micro RNA. It uses siRNA or miRNA as a template for recognizing complementary mRNA. When it finds a complementary strand it activates RNase and cleaves the RNA. This is important against viral infections, which uses double stranded RNA as an infectious vector. |
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| is a system within living cells that takes part in controlling which genes are active and how active they are. miRNA and siRNA are central to this. They can bind to other RNA and either increase or decrease their activity by preventing or producing a protein. |
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| short interfering RNA (siRNA) |
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| (sometimes known as silencing RNA) is a class of double stranded RNA molecules (20-25 nuc) that are involved in RNA interference pathway, where it interferes with the expression of a specific gene. They are processed by a dicer, which converts long dsRNAs or small hairpin RNAs into siRNA |
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| (small nuclear RNA) is a class of small RNA molecules that are found within the nucleus of eukaryotic cels. (Transcribed by RNA poly II or III and involved in RNA splicing, regulation of transcription factors or RNA poly II and maintaining telomeres. |
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| are RNA protein complexes tat combine with unmodified pre-mRNA and various other proteins to form a spliceosome, a large RNA protein molecular complex upon which splicing of pre-mRNA occurs. It is essential to the removal of introns from pre-mRNA. IT is composed of protein molecules and RNA. |
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| is a complex of specialized RNA and protein subunits that removes introns from a transcribed pre-mRNA (hnRNA) segment. It is composed of five snRNPs. |
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| is a modification of an RNA after transcription in which introns are removed and exons are joined. This is needed for the typical eukaryotic messenger RNA before it can be used to produce a correct protein through translation. |
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| is simply a strand of DNA that contains both introns and exons. These are found mainly in higher level eukaryotes. |
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| is a special form of RNA processing in eukaryotes where exons from two different primary RNA transcripts are joined end to end and ligated . (Normal cis-splicing processes a single molecule.the car |
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| After transcription begins what is added to the 5' end of mRNAs |
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| Spliceosomes contain what that are responsible for splicing? |
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| Polyadenylation occurs how? The pre mRNA is cleaved to do what |
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| Cotranscriptionally, it is cleaved to generate a new 3' end to which the poly A tail is added. |
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| In mRNA editing _____ editing is specfic for spliced transcripts and _____ editing occurs on pre-mRNAs with introns still present. |
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| How can gene expression be silenced? What does this require and how does it work |
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| RNA interference- Short RNAs (siRNA and miRNAs) are incorporated into RNA induced silencing complexes. |
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| hnRNA has a broad size range and is composed of what? What must happen to it? |
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| It is composed of pre-mRNA, they have to be trimmed to form shorter RNAs. |
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| T or F Eukaryotic pre-mRNAs are also polyadenylated |
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| mRNA's are capped where and by what |
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| at the 5' end by 7-methylguanosine |
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| The ____ is attached early in transcription, when the nascent pre-mRNA chain is only 20-30 nucleotides long |
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| Why does CTD play a role in capping? |
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| Capping enzymes bind directly to the CTD but the CTD must be phosphorylated on Ser-5 of the heptapeptide repeats |
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| Eukaryotic pre-mRNAs have what that must be removed? |
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| Coding regions are found where? |
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| In the exons (exons mean where the things that are expressed reside) |
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| What are generally not well conserved? |
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| Introns and non coding regions |
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| Pre-mRNAs that are alternatively spliced produce what? In this what happens with the exons? |
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| Different RNAs- Constitutive exons are included in all, but regulated exons is retained in only some mRNAs |
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| What happens in trans-splicing |
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| exons from two different mRNAs are spliced together. |
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| What specific sequences does splicing require? |
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| the 5' splice site, the 3' splice site, and the branchpoint sequence. |
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| they assemble to form a spliceosome that excises introns and joins the exons. |
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| The snRNAs are exported to the cytoplasm, where they are processed and joined to the Sm proteins. The snRNP is then transported back into the nucleus |
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| Splicing can be regulated through what |
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| Intronic and exonic splicing enhancers or silencers. |
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| Splicing beings when, and what stimulates spliceosome assembly |
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| During transcription, and CTD stimulates assembly |
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| Polyadenylation occurs in two stages, what are they |
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| The pre-mRNA is cleaved at a poly(A) site, and a poly (A) tail is added at the newly generated 3' end |
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| it binds certain factors for polyadenylation |
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| What takes place after cleavage and take place downstream of the poly A site |
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| transcription termination |
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| ____ editing can occur in spliced transcripts |
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| What must happen to mRNAs for translation to occur |
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| They must be transported to the cytoplasm |
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| ______ editing can occur in unspliced transcripts |
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| How are splicing and export coupled? |
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| The RNA export factor is recruited to the spliceosome, and the mRNA is targeted for export to the cytoplasm through the nuclear pores |
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| ______ is gene silencing through double stranded RNA |
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| A dicer enzyme does what? |
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| It converts double stranded RNA into siRNA molecules that are incorporated into a RISC |
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| miRNAs do what, and what are they assembled into |
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| They regulate mRNA translation or cause mRNA degradation. They are assembled into RISC |
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| What sequences would you specifically look for to spot an intron |
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| 5' GU, 3' AG, some where between UACUAAC |
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| Eukaryotic mRNA and hnRNA both have _____ at their 3' ends |
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| Eukaryotic mRNA molecules have ____ at their 5' end |
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| T or F Eukaryotes use a variety of pathways to form 5' m7G caps |
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| The carboxy terminal domain of the largest subunit of RNA polymerase II must be ____ on Ser-5 to target a transcript for capping |
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| Amino acid coding regions within eukaryotic genes may be interrupted by ____ regions |
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| T or F- Exons tend to be conserved during evolution whereas introns usually are not as tightly conserved. |
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| Two splicing intermediates resemble _____ |
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| _____ permits a cell to recode genetic information in a systematic and regulated fashion. |
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| Pre-mRNA requires specific sequences for precise ____ to occur |
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| A single ___- can be processed to produce two or more different mRNA molecules |
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| ____ assemble to form a spliceosome, the splicing machine that excises introns |
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| Transcription termination takes place downstream from the ____ |
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| ____ molecules can silence gene expression |
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| the ____ pathway blocks mRNA translation or causes mRNA degradation |
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| T or F Splicing begins as a cotranscriptional process and continues as posttranscriptional process |
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