1. Chapter 8: Transcription and RNA processing
Fig. 8-1

2. Fundamental chemical distinctions of DNA and RNA
2’ carbon
Methyl in thymine pp

3. Fig. 8-3

4. General types of RNA Informational: mRNA (most diverse)
Functional: tRNA
rRNA (most abundant)
snRNA
scRNA

5. Transcription (DNA-dependent RNA synthesis)
Requirements:
RNA polymerase
template DNA (one strand)
ribonucleoside triphosphates (ATP, GTP, CTP, UTP)
assorted cofactors (e.g., Mg++)
Directionality:
RNA always synthesized 5'3'
template DNA is read 3' 5'
RNA is complementary to its template DNA

6. Types of RNA polymerase
Prokaryotes: single enzyme complex
Eukaryotes: three types
Pol I transcribes rRNA genes
Pol II transcribes mRNA genes
Pol III transcribes tRNA, some snRNA genes

7. Genes may be transcribed from either DNA strand
(may be divergently transcribed)
Fig. 8-4

8. Fig. 8-5

9. Transcription of rDNA genes in amphibian oocyte
Fig. 8-6

10. Polarity and complementarity of DNA and RNA strands
Fig. 8-7

11. Prokaryote 5’-ends & consensus sequences
Fig. 8-8

12. Prokaryote transcription initiation
Fig. 8-9

13. Post-initiation transcription steps
Fig. 8-10

14. Example of a prokaryotic transcription terminator
(a hairpin loop structure)
Fig. 8-11

15. Eukaryotic transcription initiation requires
the ordered assembly of a preinitiation complex
(general transcription factors)
(includes specific
transcription factors)
Fig. 8-12

16. Pre-mRNA processing in eukaryotes
5’ cap addition (7-methylguanosine addition by
guanyltransferase)
Splicing to remove introns

17. Fig. 8-13

18. Pre-mRNA splicing in eukaryotes
Spliceosome: a ribonucleoprotein complex consisting
of snRNAs + proteins + pre-mRNA
Highly conserved RNA sequences
at the intron/exon boundaries 
Recruit snRNAs and proteins that assemble
into the spliceosome complex
Highly ordered, sequential series of
reactions cleave away intron and join
together the flanking exons

19. Common elements of an intron that direct proper splicing
Fig. 8-15

20. Fig. 8-16

21. Differential splicing creates diverse mRNAs from a single gene
Fig. 8-14

22. Pre-mRNA processing in eukaryotes
5’ cap addition (7-methylguanosine addition by
guanyltransferase)
Splicing to remove introns
3’ polyadenylation
- Endonuclease cleavage of pre-mRNA
~20 nucleotides 3’ to AAUAAA
- Addition of up to several hundreds of A’s
to 3’ end by poly(A) polymerase

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