1. G ENE R EGULATION

2. ALL genes are not expressed ALL the time. How? Operon Operon – a group of genes that operate together

3. E X. E. COLI LAC OPERON Allows bacteria to use lactose as food. 3 genes: 1. Promotor 1. Promotor – RNA Polymerase binds to begin transcription

4. 2. Operator 2. Operator – Region to which a repressor binds to prevent transcription  Repressor  Repressor – protein that blocks transcription  When lactose is present, it binds to the repressor protein

5. 3. Gene Protein 3. Gene Protein – When the repressor protein changes shape and falls off the operator, transcription of the gene is possible

6. H OX G ENES (“M ASTER C ONTROL G ENES ”) differentiation Control cell differentiation, when different cells gain different functions. Lab mutations: Replaced fly’s antennae with its legs Mouse eyes on fly legs

7. M UTATIONS AND C ANCER What is cancer? What causes cancer? Cancer is caused by an accumulation of mutations in the same cell. What causes mutations? 1. UV Light can modify nucleotides

8. 2. Radiation can break phosphate backbone 3. Mistakes created during DNA replication (1 out of every 100,000,000 bases)

9. 4. Other carcinogens like cigarette smoke, asbestos, and pesticides can bind with DNA and cause it to be mis-read. 5. Viruses (like HPV and Hep B) How are mutations inherited? Germ line mutations