Weaver eoc answers 16

Weaver eoc answers 16 - Answers to Weaver end of chapter...

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Answers to Weaver end of chapter questions 1Chapter 16 Other RNA Processing Events 1. See Figure 16.2, top line. The 45S RNA is the mammalian rRNA precursor. 2. RNase P removes the extra nucleotides at the 5'-end of a tRNA precursor. It is unusual in that it contains both an RNA and a protein subunit, and the RNA subunit (the M1 RNA) has the catalytic center. 3. For trans-splicing, see Figure 16.10. For cis-splicing, see Figure 14.4. The difference between cis- and trans-splicing centers on the shape of the splicing intermediate. It is Y-shaped in trans-splicing and lariat-shaped in cis-splicing. These shapes are also shown in Figure 16.11. 4. See Figure 16.12. Figure 16.11 explains how the production of a labeled 100-nt piece of RNA is consistent with cis-, but not trans-splicing. 5. RNA editing is the change in base sequence of an RNA after it is synthesized. This occurs naturally by adding or subtracting UMPs, or by deaminating AMPs to IMPs, or CMPs to UMPs. A cryptogene is a gene that gives rise to an RNA that will be edited. Figure 16.14, top, shows the sequence of the COXII cryptogene. 6. See Figure 16.16. PCR using edited 3'-primers and unedited 5'-primers yields a signal, but PCR using unedited 3'-primers and edited 5'-primers does not. 7. See Figure 16.20. 8. See Figure 16.19. This Northern blot, probed with oligonucleotides that should hybridize to gRNAs, shows signals corresponding to the gRNAs. 9. Mice with a defective ADAR2 gene die shortly after weaning, showing that this gene is essential for life. ADAR2 is known to deaminate a specific adenosine in the transcript of a gene ( GluR-B ) encoding an ion channel, changing it to an inosine, and changing the meaning of the codon from glutamine to arginine. Seeburg and colleagues mutated this codon so it encoded arginine, then tested this mutated gene in mice with a defective ADAR2 gene. The ADAR2 mutation was no longer lethal, showing that the GluR-B transcript is the only critical target of ADAR2.
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Weaver eoc answers 16 - Answers to Weaver end of chapter...

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