Term
| When does 5' capping occur? |
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Definition
| Almost immediately after TXN starts |
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Term
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Definition
| A 7-methyl guanine attached in a 5' to 5' kinda way. This can attach because the first nucleotide of the nascent RNA is a triphosphate |
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Term
| What is the purpose of the 5' cap? |
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Definition
| It binds to the ribosome for translation. It protects the mRNA from RNAse enzymes. |
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Term
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Definition
| It is a bunch of AAAAAAs. it is poly(A) tail. |
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Term
| What does Poly(A) polymerase do? |
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Definition
| It is a template independent RNA polymerase that adds 100-200 A's at the end of the nascent mRNA. |
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Term
| How is the poly(A) tail protected from exonucleases? |
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Definition
| Poly(A) binding proteins come in and bind it to protect it. |
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Term
| when does RNA splicing occur? |
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Definition
| As TXN progresses, introns are spliced out. |
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Term
| What do introns always begin and end with? |
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Definition
| Begin with GU and end with AG. |
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Term
| What lies near the GU at the beginning and AG at the end? |
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Definition
| You have loose consensus sequences. |
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Term
| what carries out splicing? |
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Definition
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Term
| what are spliceosomes made of? |
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Definition
| small nuclear RNAs, and small nuclear ribonucleoproteins (snRNA's plus attached proteins) |
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Term
| When the spliceosome recognizes the consensus sequences and splices, what kind of RNA gets formed? |
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Definition
| You get lariat RNA because there is some kind of binding event that happens. This is degraded by ribonucleases. |
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Term
| what is the term for the sum total of all RNA's present in human cells? |
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Definition
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Term
| What does alternative splicing do? |
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Definition
| It splices in different places to give you different proteins. |
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Term
| How is alternative splicing regulated? |
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Definition
| Exonic Splicing Enhancers are RNA sequences (in exons) to which Splice Regulator proteins bind. THIS ENABLES SPLICEOSOME TO BIND IN EXONIC SEQUENCES (it usually cannot). |
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Term
| What is an example of how a splicing defect could mess things up? |
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Definition
| Aberrant splicing: You could get a single nucleotide change that causes a splice site to be in the wrong place too early in the intron. Then the exon gets a piece of intron added on. This is especially bad if the intron is not a multiple of 3, because then you get a frameshift mutation! |
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