1. Gene Expression (Epigenetics) Chapter 11

2. What you need to know The functions of the three parts of an operon. The role of repressor genes in operons.

3. Bacteria Gene Expression Operons are clusters of genes in bacteria They can be turned on and off Parts: 1.Operator: an on/off switch for all the genes 2.Promoter: RNA Polymerase attachment site 3.Genes: DNA for each protein in the operon

4. Operons: On/Off Regulatory genes – make repressor proteins that bind to operators and block RNA Polymerase (turn the gene off) 1.Repressible operon – gene usually on 2.Inducible operon – gene usually off

5. Bozeman Video http://www.youtube.com/watch?v=1 0YWgqmAEsQhttp://www.youtube.com/watch?v=1 0YWgqmAEsQ

6. In your notes: What is an operon and how does it work? What is the purpose of an operon?

7. Eukaryotic Gene Expression Chromosomes are composed of Nucleosomes Nucleosomes are DNA tightly wrapped around histones (like a spool of thread) RNA polymerase cannot make (because it doesn’t fit) mRNA from DNA tightly wrapped around histones

8. In Your Notes Why can Chromosomes be considered coils of coils of coils of DNA?

9. Eukaryotic Gene Expression: 9 valves 1.DNA unpacking 2.Transcription (prok also) 3.Addition of cap and tail 4.Splicing 5.Flow through nuclear envelope 6.Breakdown of mRNA (prok also) 7.Translation (prok also) 8.Cleavage/modification/activation (prok also) 9.Breakdown of protein (prok also)

10. Cell Specialization/Differentiation Cell differentiation is the process by which cells become specialized –Muscle tissue, neural tissue, etc. Cells all have the same DNA but display dramatic variations in gene expression

11. Animal Development Cell-cell signals are molecules made by cells (external hormones) that influence other cells (induction) Homeotic gene: master control gene that regulates many other genes to determine anatomy

12. In Your Notes: How are homeotic genes in multicellular eukaryotes such as yourself similar to operons in bacteria?