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

2. Fig. 18-4b (b) Lactose present, repressor inactive, operon on mRNA Protein DNA mRNA 5 Inactive repressor Allolactose (inducer) 5 3 RNA polymerase Permease Transacetylase lac operon  -Galactosidase lacY lacZlacAlac I

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

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

5. Figure 18.7 Amino acids available for chemical modification Histone tails DNA double helix Nucleosome (end view) (a) Histone tails protrude outward from a nucleosome Unacetylated histones Acetylated histones (b) Acetylation of histone tails promotes loose chromatin structure that permits transcription

6. Figure 7-80 Molecular Biology of the Cell (© Garland Science 2008)

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

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

9. Figure 7-82 Molecular Biology of the Cell (© Garland Science 2008)

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

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

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

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

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

15. Fig. 12-17b Cyclin is degraded Cdk MPF Cdk M S G1G1 G 2 checkpoint Degraded cyclin Cyclin (b) Molecular mechanisms that help regulate the cell cycle G2G2 Cyclin accumulation

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

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

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

19. Nematodes with a GFP transgene Treated with GFP dsRNA

20. dsRNA can reduce gene expression for generations

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