Biotech 2011-05-eukaryotic-genes

Notes de l'éditeur

1. 1.        What is a primary transcript? 1.        What does splicing do? 2.        On what primary transcripts does splicing operate? 3.        How else is an mRNA modified? 4.        How else is a tRNA modified? 5.        What is a rRNA primary transcript called? 6.        How is it processed?
2. 1.        What is an intron? 1.        In what organisms are introns more abundant? 2.        In what organisms are introns larger? 1.        What characterizes intron-less genes in higher organisms? 2.        What is an example of an intron-less gene? What else is unique about histone gene transcripts?
3. 1.        What is a D-loop? 2.        What do D loops demonstrate?
4. 1.        How many classes of introns are there?
5. 1.        In what types of genes are group I introns found? 2.        What characterizes a self-splicing intron? 3.        What type of reaction is used by self-splicing introns? 4.        What characterizes transesterification reactions? 5.        Although freely reversible, why are introns not put back into primary transcripts by transesterification reactions? 6.        What cofactor is required by group I introns? 7.        How is the free intron modified following a group one splicing reaction? 8.        It the intron linear or circular after removal?
6. 1.        What attacks the intron exon boundary in a group II reaction? 2.        What is the structure of the excised intron? 1.        What is responsible for the processing of most mRNA?
7. 1.        What is contained by the snRNP? 2.        How do snRNA’s function?
8. 1.        What results from the splicing of nuclear mRNA? 2.        Does the splicing mechanism require ATP?
9. 1.        In what cell type are enzyme dependent splicing reactions carried out? 2.        How does a 2’ phosphate result on the 3’ hydroxyl of an exon boundary in yeast tRNA splicing? 3.        How is the phosphodiester linkage established between exons in the above mechanism?
10. 1.        Where does capping occur? 2.        What is capped? 3.        What is the final structure of the cap? 4.        When is the terminal G methylated?
11. 1.        Where is the AAUAAA sequence found? 2.        How is a poly A tail added on? 3.        How long are poly A tails?
12. 1.        What is meant by a functional domain of a protein? 2.        How can RNA processing affect the appearance of functional domains in a protein? 3.       
13. 1.        What is meant by cell type specific? 2. What advantage is there to alternatively splicing an mRNA?
14. 1.        What is meant by exon skipping?
15. 1.        What is the expected result of the use of a cryptic splice site?
16. How is IgM held on the surface of a cell? 4.        What causes release of IgM? 5.        Is this an example of alternative cleavage or alternative processing of IgM mRNA?
17. 1.        What is included on a preribosomal RNA? 1.        What is one justification for producing RNA by this mechanism?
18. 1.        What cleaves the 5’ end of tRNA during processing? The 3’end? 1.        What is the central difference between RNAse P and RNAse D? 2.        What is the significance of the CCA sequence on the 3’ end? 3.        How is the CCA added? 4.        How is the anticodon loop created? 5.        What other modifications are carried out on maturing tRNA?
19. 1.        Why aren’t most ribozymes true catalysts? 2.        What type of ribozyme can act as a true catalyst?
20. 1.        How does RNA degradation proceed? 2.        What structural elements can inhibit exonucleases?