1. Control of Gene Expression Big Idea 3: Living systems store, retrieve, transmit, and respond to info essential to life processes.

2. Essential Knowledge 3B1: Gene regulation results in differential gene expression, leading to cell specialization. 3B2: A variety of intercellular and intracellular signal transmissions mediate gene expression

3. Much Diversity due to Gene Expression Each tissue in our body is very different despite having the same DNA Even identical twins have many differences due to gene expression

4. Some Basics: Regulatory Sequences Stretches of DNA that interact w/ regulatory proteins to control transcription. Allows RNA Polymerase to bind on. – AKA promoter (TATA box) – Enhancers are sequences that increase transcription

5. Some Basics: Regulatory Genes Code for proteins or mRNAs which affect gene expression – Ex: microRNAs – Repressor proteins – Transcription factors/ enhancers

7. Some Basics: Operons Simple gene expression mechanisms in prokaryotes

8. Components of the Operon Operator, sequence next to the promoter (On/Off switch)  If repressor protein is on it, then off…can’t make genes Promoter (where RNA polymerase binds) Genes that work together

9. Types of Operons Some genes are normally “off” and can be turned “on”  Presence of a molecule induces gene expression or enhances gene expression Some genes are normally “on” and can be turned “off”  Presence of a molecule represses gene expression

10. Inducing Gene Expression: Lac Operon, + Control If lactose present, bacteria need to make lactase to break it down. Lactose binds to repressor on operator  repressor is released from operator RNA polymerase now fits onto promoter region to make mRNA  protein lactase.

11. Negative Control Case Study: Trp Operon Tryptophan fits in repressor  blocks RNA polymerase. Once out of tryp, repressor changes shape to allow promoter available to make more tryptophan  turns transcription on.

12. Ribosomal Genes… Always on!!! Always Expressed!

13. In Eukaryotes… No operons… Gene expression involves regulatory genes, regulatory elements, and transcription factors.  All work together to determine how much product is made.

14. Transcription Factors Bind to specific DNA sequences Some activate (increase expression) and some are repressors (decrease expression)

15. Signal Transmission Within and b/t cells mediates gene expression. Ex: cytokines regulate gene expression to allow cell replication and division.

16. Within and b/t cells mediates cell function. Ex: HOX genes (homeotic genes) Signal Transmission

17. Mr Anderson http://www.youtube.com/watch?v=3S3ZOmle Aj0 http://www.youtube.com/watch?v=3S3ZOmle Aj0

18. Lac Operon or Trp Operon Flow Map