1. Chapter 8: RNA General structure of RNA
Process of transcription in prokaryotes and eukaryotes
Other functions of RNA, small nuclear RNAs (snRNAs), micro-RNAs (miRNAs) and small interfering RNAs (siRNAs)

2. Announcements
Quiz 6
Presentation on Wed. from first group on journal article
Due today
In-Class on DNA
Homework chapter 7 and 8

3. DNA codes for proteins
Once the DNA sequence for humans was known, what else can be determined??
If E. coli has 3200 genes, Drosophila has 13,600 genes, then humans must have….

4. The results of the GeneSweep pool
Lee Rowen from Institute for Systems Biology

5. The pulse-chase experiment
How is information transferred from DNA to proteins?
What was determined from this?

6. What do you know about RNA?

7. Different classes of RNA
Messenger RNA
Functional RNA (found in all cells)
tRNA
rRNA
Other Functional RNAs
Small nuclear RNAs
MicroRNAs
Small interfering RNAs

8. Which strand of DNA?
Only one strand is template
Varies with the gene

9. Overview of Transcription

10. Prokaryotes vs Eukaryotes

11. Transcription in prokaryotes

12. Transcription in prokaryotes: Initiation
Composed of five subunits plus sigma factor
Sigma factor binds to the promoter region

13. Transcription in prokaryotes: Elongation and termination

14. Transcription in prokaryotes: Termination

15. Transcription in eukaryotes
More complex….more genes
Many types of RNA Polymerase
Cell architecture different
RNA processing

16. Initiation in eukaryotes
TATA-binding protein binds to TATA region
Other GTFs bind and attract RNA Polymerase II

17. Cotranscriptional processing
5’ cap made of 7-methylguanosine residues

18. Cotranscriptional processing
Conserved sequence (AAUAAA) signals an enzyme to cut RNA
Poly(A) tail is added to the 3’ end of transcript

19. Cotranscriptional processing
Coding regions (exons) are spliced from non-coding regions (introns)

20. Splicing occurs at conserved regions

21. Spliceosome assembly
Requires snRNPs (protein and snRNAs)

22. Benefits of alternative splicing?

23. Self splicing introns?
1981 Tom Cech identified rRNA from protozoan that could excise own intron
RNA that are enzymes??
What does this mean about the function of RNA?

24. Genes code for proteins…right?
1993 Ambros discovered new gene (lin-4 gene)
Does not code for a protein!
microRNAs are discovered!

25. Silence genes with dsRNA?
Inserted dsRNA into embryos
Results suggested gene silencing occurred!

26. What happens if you insert a transgene?
Transgene is….?
What did they expect to see?
What did they actually see?
Cosuppression!

27. How can transgene result in dsRNA?

28. More evidence of gene silencing
Viral gene inserted into plants
Plant is resistant to viral infection
How??

29. RNA interference (RNAi)
Model for eliminating mRNA in a cell

30. New Roles for RNA! snRNAs miRNAs and siRNAs
Gene silencing
What other applications are possible with miRNAs and siRNAs?