Group 6 GERMS, DRUGS and GENES: Revealing mechanisms of gene expression using antibiotics

1. Group 6 GERMS, DRUGS and GENES: Revealing mechanisms of gene expression using antibiotics Alejandro Calderon-Urrea Nancy Connell Nigel Crawford Mamta Rawat Ella Tour Facilitator: Ken Burtis Level: Lower Division Biology Class for Majors

2. Learning Goals: The student will be able to understand how genotype determines phenotype. The student will identify steps in gene expression and how some drugs affect different levels of gene expression.

3. Learning Outcomes • The student will find and illustrate the mechanisms of action of certain antibiotics and relate these actions of antibiotics to steps in gene expression. • The student will be able to explain how resistance to antibiotics arises from a change in the genetic material of the cell. • The student will be able to apply principles of antibiotic resistance in bacteria to drug resistance in eukaryotic cells. • The student will propose strategies for the development of new drugs.

4. GENOTYPE ? PHENOTYPE

5. GENOTYPE Antibiotics PHENOTYPE (DEATH)

6. Internet search (2 minutes) Pair up and pick one of the following antibiotics. Each pair search the internet and find out about the target of the antibiotic (each group covers all three antibiotics). 1. Ciprofloxacin (cipro)2. Rifampicin (rifampin)3. Tetracycline Group share and drawing exercise (3 min) Draw a bacterial cell on poster paper and illustrate the targets of antibiotics.

7. Mechanisms of action of three antibiotics Tetracycline Translation Ribosome DNA replication Transcription Gyrase RNA Pol Rifampicin Ciprofloxacin

8. Clicker question (2 min) How do antibiotics become ineffective against bacterial infection? Human body develops mechanisms to inactivate the antibiotic. Treating bacteria with antibiotics changes their physiology so they become resistant The antibiotic causes the mutation in the bacteria which leads to resistance Existing mutants in the bacterial population that are already resistant to the antibiotic are selected and proliferate All of the above In class: Peer instruction (Vote, Think pair share, Re-vote) followed by discussion of different options by instructor

9. Genotype 2 Genotype 1 Phenotype 1: Susceptibility Phenotype 2: Resistance

10. Nancy http://www.niaid.nih.gov/topics/antimicrobialResistance/

11. Nancy http://www.niaid.nih.gov/topics/antimicrobialResistance/

12. Nancy Genotype 2 Genotype 1 Phenotype 1: Susceptibility Phenotype 2: Resistance

13. Ella We have learned that resistance arises in populations by mutation or acquisition of new genes. How could a mutation lead to antibiotic resistance? Propose mechanisms or targets in bacteria that could be altered to produce resistance. Group share

14. Use the internet to find mechanisms of resistance for your antibiotic. Report to group. Use your drawings to illustrate what you found. “Call out” three groups for each antibiotic. (skip) 1. Ciprofloxacin (cipro)2. Rifampicin (rifampin)3. Tetracycline

15. Can you think of an instance in which eukaryotic cells acquire resistance to drugs or chemicals? Group share. Report out.

16. Homework A patient is undergoing cancer treatment with an anti-cancer drug. For a while, the cancer is responding and the tumor is shrinking significantly. However, after 6 months, the cancer comes back: the tumor cells continue to proliferate even when the dosage of the drug is increased.  A. Based on what you've learned today, suggest two possible mechanisms that allowed the cancer cells to become resistant to the drug. B.  You wish to find a new drug to treat this cancer. What process or molecule in these resistant tumor cells would you propose to target in your new drug study? The answers will be discussed next class.

17. Pre-test/Post-test • Explain how genetic information is transferred from DNA to RNA to proteins. Include the terms: DNA replication, transcription, translation. (LOC) • What could be the consequences to this flow of information if a mistake occurs during DNA replication? (LOC/HOC) • Describe four examples of mechanisms of action of an antibiotic on a bacterial cell. (LOC) • Explain a mechanism of antibiotic resistance. Provide an example. (LOC) • Why aren’t antibiotics as effective in treating disease as they used to be? (HOC)

18. Summative assessment: The student will find and illustrate the mechanisms of action of certain antibiotics and relate these actions of antibiotics to steps in gene expression. A2-A4 The student will be able to explain how resistance to antibiotics arises from a change in the genetic material of the cell. A7 The student will be able to apply mechanisms of resistance to antibiotics in bacteria to resistance to drugs in eukaryotic cells. A8 The student will propose strategies for the development of new drugs. HW

19. 105 104 103 102 10 # of bacteria No antibiotic A B This graph shows a typical growth curve of a bacterium such as E. coli growing in liquid culture. What would the growth curve look like if antibiotic were added to the culture at the beginning of the experiment (A)? Show at least two possibilities. What if you add two antibiotics? How would the curve change if you added antibiotic at the time designated by B? Would the shape of the curve change for different antibiotics (ciprovs tetracycline) with mechanisms of action that you learned about? Time, hours