1. Gene Regulation in Eukaryotic Cells

2. Gene regulation is complex Regulation, and therefore, expression of a gene is complex. Regulation of these genes require all of these to interact together –Regulatory genes –Regulatory proteins –Transcription factors

3. Transcription Factors Transcription factors (proteins) bind to specific DNA sequences and/or other regulatory proteins Some of the these transcription factors are activators, some are repressors

4. Many things must occur for a gene to be expressed Combination of transcription factors binding to specific DNA sequences at any one time determines how much transcription occurs or doesn’t occur

5. Some genes are continuously expressed Some genes are always turned “on,” which means they are always expressed (transcription, translation…) –Ribosomal genes –Glycolysis genes

6. What if we share similar genes with other organisms? Gene regulation leads to some phenotypic differences between organisms with similar genes –Arm bones in humans and front leg bones of dogs –Since we have similar bone structure, this suggests Common ancestry Similar DNA sequences

7. Transcription factor binding in eukaryotes; influences The interactions of transcription factors with one another or with DNA can be influenced by signals –From within the cell –From outside the cell Signals are integrated at the promoter

8. DNA-level Regulation Enhancer regions and activator proteins Acetylation of histones Methylation of C’s on DNA

9. Stimulation of transcription by an enhancer

11. Transcription-level Regualation Alternative splicing –Varies in different tissues (skin vs. liver vs. lung) RNAi (2006 Nobel Prize in medicine) –siRNA and miRNA 20-ish nucleotides long –Then use of RISC and Dicer Dicer is the enzyme that breaks apart ds RNA

12. Alternative Splicing

13. RNAi

16. Post-Translational Regulation of Expression Modifications of protein –Phosphorylation Targeting specific proteins to be degraded at a certain time

17. Importance of gene regulation The amount and time of gene expression can be regulated at any one of several steps between the DNA and the final functional gene product

18. Importance of gene regulation Gene regulation results in differential gene expression. This leads to cell specialization.

20. Regulation of transcription in eukaryotes