1. Copyright © 2009 Pearson Education, Inc. Chapter 14 The Genetic Code and Transcription Copyright © 2009 Pearson Education, Inc.

2. Figure 14.1

3. Copyright © 2009 Pearson Education, Inc. Written in linear form Each word consists of 3 ribonucleotide letters The code is unambiguous The code is degenerate The code contains 1 start and 3 stop codons The code is commaless The code is non-overlapping The code is (nearly) universal Characteristics of the Genetic Code

4. Copyright © 2009 Pearson Education, Inc. Evidence for the Triplet Code Three bases is the minimum length needed to code for 20 amino acids Reading frame studies

5. Copyright © 2009 Pearson Education, Inc. Figure 14.2

6. Copyright © 2009 Pearson Education, Inc. Evidence for a Non-Overlapping Code If code was overlapping: Amino acid sequences would be restricted Base substitutions would affect two adjacent amino acids Translation would be too complex to be efficient

7. Copyright © 2009 Pearson Education, Inc. Evidence for a Commaless and Degnerate Code Frameshift would result in many nonsense mutations

8. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Deciphering the Code Made possible by advancements that: Allowed protein synthesis in vitro Synthesizing RNA strands in vitro First studies utilized homopolymer RNAs Advanced to copolymers and heteropolymer RNAs

9. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Polynucleotide Phosphorylase

10. Copyright © 2009 Pearson Education, Inc. Table 14.1

11. Copyright © 2009 Pearson Education, Inc. Figure 14.4

12. Copyright © 2009 Pearson Education, Inc. Figure 14-5 Copyright © 2006 Pearson Prentice Hall, Inc. Figure 14.5 Triplet-Binding Assay

13. Copyright © 2009 Pearson Education, Inc. Table 14.2

14. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Repeating Copolymers Long RNA molecules consisting of short, repeated segments Begin with di-, tri-, or tetra- nucleotides Connect together using special enzymes By comparing data from several experiments, it is possible to assign specific codons to specific amino acids

15. Copyright © 2009 Pearson Education, Inc. Figure 14.6

16. Copyright © 2009 Pearson Education, Inc. Table 14.3

17. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Interesting Patterns Among the Codons The Wobble Hypothesis Ordered code Initiation codons Termination codons

18. Copyright © 2009 Pearson Education, Inc. Figure 14-7 Copyright © 2006 Pearson Prentice Hall, Inc. Figure 14.7

19. Copyright © 2009 Pearson Education, Inc. Table 14.4

20. Copyright © 2009 Pearson Education, Inc. Table 14.5 The Code is (Almost) Universal

21. Copyright © 2009 Pearson Education, Inc. Figure 14.8 Overlapping Genes

22. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Observations Suggesting RNA is the Intermediate DNA is in the nucleus of eukaryotic cells, but protein synthesis happens on ribosomes in the cytoplasm RNA is synthesized in the nucleus RNA migrates to the cytoplasm Amount of RNA is generally proportional to the amount of protein in the cell

23. Copyright © 2009 Pearson Education, Inc. Table 14.6

24. Copyright © 2009 Pearson Education, Inc. Figure 14.3 RNA Polymerase Same general substrate requirements as DNA Polymerase No primer is needed Holoenzyme with several subunites (E. coli) β and β’ are catalytic σ plays a regulatory function Prokaryotes have a single form of RNA pol (with different σ) Eukaryotes have three distinct RNA pols

25. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Consensus Sequences in Prokaryotic Promoters TATAAT aka: Pribnow box 10 nucleotides upstream from the transcription initiation site TTGACA 35 nucleotides upstream from the transcription initiation site These are considered cis-acting elements Trans-acting elements bind to the cis elements

26. Copyright © 2009 Pearson Education, Inc. Figure 14.9a

27. Copyright © 2009 Pearson Education, Inc. Figure 14.9b

28. Copyright © 2009 Pearson Education, Inc. Figure 14.9c

29. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Polycistronic mRNA

30. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Transcription in Eukaryotes Occurs in the nucleus 3 different RNA polymerases Chromatin remodeling must occur Extensive interaction between cis elements and trans factors mRNA processing

31. Copyright © 2009 Pearson Education, Inc. Table 14.7 RNA Polymerases

32. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Consensus Sequences in Eukaryotic Promoters TATAAAA – The Core Promoter aka: TATA box 35 nucleotides upstream from the transcription initiation site GGCCAATCT aka: CAAT box 80 nucleotides upstream from the transcription initiation site Others (Enhancers too)

33. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Eukaryotic Trans-acting Factors Proteins called transcription factors Facilitate RNP II binding General transcription factors TFIID – aka TATA Binding Protein (TBP) Specific transcription factors

34. Copyright © 2009 Pearson Education, Inc. Figure 14.10 Eukaryotic mRNA Processing

35. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Introns vs Exons Not all of a eukaryotic mRNA is translated into proteins Intervening sequences – introns Are removed during splicing Expressed sequences – exons Translated into proteins

36. Copyright © 2009 Pearson Education, Inc. Figure 14.11 Heteroduplex

37. Copyright © 2009 Pearson Education, Inc. Figure 14.12

38. Copyright © 2009 Pearson Education, Inc. Table 14.8

39. Copyright © 2009 Pearson Education, Inc. Figure 14.3 Introns are Categorized Group I Group II Nuclear derived pre-mRNA transcripts

40. Copyright © 2009 Pearson Education, Inc. Figure 14.13 Group I Introns

41. Copyright © 2009 Pearson Education, Inc. Figure 14.14 The Spliceosome

42. Copyright © 2009 Pearson Education, Inc. Figure 14.15