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:
Operator: an on/off switch for all the genes
Promoter: RNA Polymerase attachment site
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)
Repressible operon – gene usually on (repressor protein is off; requires a co-repressor)
Inducible operon – gene usually off (repressor protein on; turned off by an inducer)

5. Bozeman Video

6. 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

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

8. 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

9. 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
Signal Transduction pathways are a series of reactions inside the target cell that alter gene expression