Fig. 17-5

1. Fig. 17-5 Second mRNA base First mRNA base (5 end of codon) Third mRNA base (3 end of codon)

2. the mechanism of translation Amino acids Polypeptide tRNA with amino acid attached Ribosome Trp Phe Gly tRNA Anticodon Codons 5 3 mRNA

3. trp operon Promoter Promoter Fig. 18-3a Genes of operon DNA trpD trpR trpE trpC trpB trpA Operator Regulatory gene Stop codon Start codon 3 mRNA 5 RNA polymerase mRNA 5 B A D C E Protein Inactive repressor Polypeptide subunits that make up enzymes for tryptophan synthesis (a) Tryptophan absent, repressor inactive, operon on

4. Precursor trpE gene Enzyme 1 trpD gene Fig. 18-2 trpC gene Enzyme 2 trpB gene Enzyme 3 trpA gene Tryptophan (a) Regulation of enzyme activity (b) Regulation of enzyme production

5. trp operon Promoter Promoter Fig. 18-3a Genes of operon DNA trpD trpR trpE trpC trpB trpA Operator Regulatory gene Stop codon Start codon 3 mRNA 5 RNA polymerase mRNA 5 B A D C E Protein Trp repressor Polypeptide subunits that make up enzymes for tryptophan synthesis (a) Tryptophan absent, repressor inactive, operon on

6. DNA Fig. 18-3b-2 No RNA made mRNA Protein Active repressor Tryptophan (corepressor) (b) Tryptophan present, repressor active, operon off

7. The actual structure of the Trp Repressor

8. Fig. 18-4b The lac operon lac operon lacY DNA lacI lacZ lacA RNA polymerase 3 mRNA mRNA 5 5 Permease Transacetylase -Galactosidase Protein Lac Repressor Inactive repressor Allolactose (inducer) (b) Lactose present, repressor inactive, operon on

9. Fig. 18-4a Regulatory gene Promoter Operator lacI lacZ DNA No RNA made 3 mRNA RNA polymerase 5 Active repressor Protein (a) Lactose absent, repressor active, operon off

10. Fig. 18-4b lac operon lacY DNA lacI lacZ lacA RNA polymerase 3 mRNA mRNA 5 5 Permease Transacetylase -Galactosidase Protein Inactive repressor Allolactose (inducer) (b) Lactose present, repressor inactive, operon on

11. Promoter Operator DNA lacI lacZ RNA polymerase binds and transcribes CAP-binding site Active CAP cAMP Fig. 18-5 Inactive lac repressor Inactive CAP Allolactose (a) Lactose present, glucose scarce (cAMP level high): abundant lac mRNA synthesized Promoter Operator DNA lacI lacZ CAP-binding site RNA polymerase less likely to bind Inactive CAP Inactive lac repressor (b) Lactose present, glucose present (cAMP level low): little lac mRNA synthesized

12. Promoter Operator DNA lacI lacZ RNA polymerase binds and transcribes CAP-binding site Active CAP cAMP Fig. 18-5 Inactive lac repressor Inactive CAP Allolactose (a) Lactose present, glucose scarce (cAMP level high): abundant lac mRNA synthesized Promoter Operator DNA lacI lacZ CAP-binding site RNA polymerase less likely to bind Inactive CAP Inactive lac repressor (b) Lactose present, glucose present (cAMP level low): little lac mRNA synthesized

13. Signal NUCLEUS Chromatin Chromatin modification Levels of gene regulation in eukaryotes DNA Gene available for transcription Gene Transcription Fig. 18-6 RNA Exon Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Protein processing Active protein Degradation of protein Transport to cellular destination Cellular function

14. Signal NUCLEUS Chromatin Chromatin modification Levels of gene regulation in eukaryotes DNA Gene available for transcription Gene Transcription - Trancriptional activation in eukaryotes Fig. 18-6 RNA Exon Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Protein processing Active protein Degradation of protein Transport to cellular destination Cellular function

15. A Eukaryotic Gene Poly-A signal sequence Enhancer (distal control elements) Proximal control elements Termination region Fig. 18-8-1 Exon Intron Exon Intron Exon DNA Upstream Downstream Promoter

16. Promoter Activators Gene DNA Distal control element Enhancer TATA box Fig. 18-9-1

17. Promoter Activators Gene DNA Distal control element Enhancer TATA box General transcription factors Fig. 18-9-2 DNA-bending protein Group of mediator proteins

18. Promoter Activators Gene DNA Distal control element Enhancer TATA box General transcription factors Fig. 18-9-3 DNA-bending protein Group of mediator proteins RNA polymerase II RNA polymerase II Transcription initiation complex RNA synthesis

19. Enhancer Promoter Albumin gene Control elements Crystallin gene Fig. 18-10 LIVER CELL NUCLEUS LENS CELL NUCLEUS Available activators Available activators Albumin gene not expressed Albumin gene expressed Crystallin gene not expressed Crystallin gene expressed (a) Liver cell (b) Lens cell

20. Signal NUCLEUS Chromatin Chromatin modification Levels of gene regulation in eukaryotes DNA Gene available for transcription Gene Transcription - Eukaryotes can control the availability of DNA for expression by altering the extent of DNA packing Fig. 18-6 RNA Exon Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Protein processing Active protein Degradation of protein Transport to cellular destination Cellular function

21. Fig. 16-21a Nucleosome (10 nm in diameter) DNA double helix (2 nm in diameter) H1 Histone tail Histones DNA, the double helix Histones Nucleosomes, or “beads on a string” (10-nm fiber)

22. Figure 18.7 Histone tails DNA double helix Amino acidsavailablefor chemicalmodification Nucleosome(end view) (a) Histone tails protrude outward from a nucleosome Acetylated histones Unacetylated histones (b) Acetylation of histone tails promotes loose chromatinstructure that permits transcription

23. Fig. 15-18 Normal Igf2 allele is expressed Paternal chromosome Maternal chromosome Histone tails Normal Igf2 allele is not expressed Wild-type mouse (normal size) Amino acids available for chemical modification Fig. 18-7 (a) Homozygote DNA double helix Mutant Igf2 allele inherited from mother Mutant Igf2 allele inherited from father (a) Histone tails protrude outward from a nucleosome Normal size mouse (wild type) Dwarf mouse (mutant) Normal Igf2 allele is expressed Mutant Igf2 allele is expressed Unacetylated histones Acetylated histones Mutant Igf2 allele is not expressed Normal Igf2 allele is not expressed (b) Acetylation of histone tails promotes loose chromatin structure that permits transcription (b) Heterozygotes

24. X chromosomes Allele for orange fur Early embryo: Allele for black fur Cell division and X chromosome inactivation Fig. 15-8 Two cell populations in adult cat: Active X Inactive X Active X Black fur Orange fur

25. Signal NUCLEUS Chromatin Chromatin modification Levels of gene regulation in eukaryotes DNA Gene available for transcription Gene Transcription -Alternative splicing can be generated Fig. 18-6 RNA Exon Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Protein processing Active protein Degradation of protein Transport to cellular destination Cellular function

26. Alternative splicing Exons DNA Fig. 18-11 Troponin T gene Primary RNA transcript RNA splicing or mRNA

27. The DSCAM gene (Drosophila): ~38,000 possible splice variants

28. Signal NUCLEUS Chromatin Chromatin modification Levels of gene regulation in eukaryotes DNA Gene available for transcription Gene Transcription - Proteins can be selectively degraded Fig. 18-6 RNA Exon Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Protein processing Active protein Degradation of protein Transport to cellular destination Cellular function

29. Fig. 18-12 Ubiquitin ligase Proteasome and ubiquitin to be recycled Ubiquitin Proteasome Ubiquitinated protein Protein to be degraded Protein fragments (peptides) Protein entering a proteasome

30. Fig. 12-17b G1 S Cdk Cyclin accumulation M G2 Degraded cyclin G2 checkpoint Cdk Cyclin is degraded Cyclin MPF (b) Molecular mechanisms that help regulate the cell cycle

31. Telophase and Cytokinesis Metaphase Anaphase Nucleolus forming Metaphase plate Cleavage furrow Fig. 12-6d Daughter chromosomes Nuclear envelope forming Centrosome at one spindle pole Spindle

32. Signal Levels of gene regulation in eukaryotes NUCLEUS Chromatin Chromatin modification Small, non-coding RNAs can affect gene regulation at multiple levels DNA Gene available for transcription Gene Transcription Fig. 18-6 RNA Exon Primary transcript Intron RNA processing Tail mRNA in nucleus Cap Transport to cytoplasm CYTOPLASM mRNA in cytoplasm Translation Degradation of mRNA Polypeptide Protein processing Active protein Degradation of protein Transport to cellular destination Cellular function

33. Nematodes with a GFP transgene Nematodes with a GFP transgene Treated with GFP dsRNA

34. dsRNA can reduce gene expression for generations

35. Hairpin miRNA Hydrogen bond Dicer Fig. 18-13 miRNA miRNA- protein complex 5 3 (a) Primary miRNA transcript mRNA degraded Translation blocked (b) Generation and function of miRNAs

36. Fig. 18-13 Hairpin miRNA Hydrogen bond Dicer miRNA miRNA- protein complex 5 3 (a) Primary miRNA transcript mRNA degraded Translation blocked (b) Generation and function of miRNAs