Microorganisms

 10th/11th grade Biology

 3 class blocks (or ~ 4 hr, over 2 days)

 Students should understand that cells are the basic unit of living things. They should also appreciate that microorganisms are a major cause of common diseases and illnesses.

 Basic properties of microorganisms and how they are harmful or helpful to humans.
 Lab activity to study the bacteriacidal effect of UV light and household bleach.

• Students should know the history of microbiology and the contributions of various scientists.

• Students should be able to compare and contrast the basic properties of bacteria and viruses.

• Students should understand the effect of antibiotics and disinfectants on bacteria growth.

• Students will learn how to culture, plate and count bacteria.
  

 Agar plates distilled water, E. coli culture, UV lamp, household bleach, culture tubes, cell spreaders, inoculation loops, disposable pipets, centrifuge tubes, measuring cylinders, incubator

Procedure

Opener

a. Do now - students read chapter on microorganisms using SQ3R method for 5-10 minutes.  Teacher and students discuss SQ3R responses for 5-10 minutes. Teacher should use this opportunity to highlight the contributions by the following people, focusing a bit more on Pasteur's experiments:

• Robert Hooke - describe cells.

• Anton van Leeuwenhoek - giardia, animalcules.

• Louis Pasteur - germ theory, immunization

b. Discussion - The teacher will engage the students by questioning the students about what they know already about bacteria and viruses, including whether or not all microorganisms are harmful.

Development

a. Engage - Teacher will use Glo-germ powder to show how bacteria can spread through contact. Class will discuss germ communication, cross-contamination, and effectiveness of sanitary practices. 

b. Lab activity - Study the effect of disinfectants (UV light and bleach) on E. coli. Teachers will demonstrate the techniques that students will use in the lab. Students will be divided into two groups:

Group I: UV light exposure time - from 10s to 30 minutes. Students in this group will add E. coli into individual culture tubes, then expose each tube to UV for different amounts of time. Students will then plate the exposed bacteria onto prepared agar plates. After overnight culture, students will record the amount of bacteria growth observed on the agar plates.

Group II: Bleach concentration - from 1% to 10%. Students in this group will make bleach solutions at 5 different concentrations and add E. coli into each solution for a fixed amount of time (30 minutes). Students will then plate the solutions onto prepared agar plates. After overnight culture, students will record the amount of bacteria growth observed on the agar plates.

Closure

 Students choose and research a specific pathogen (e.g., influenza, chlamydia etc.) and submit a 2-3 page written report. Students also present their research to the class. They should be able to clearly describe their pathogen as either a bacteria or virus, and also use correct and appropriate vocabulary.

  Students will be evaluated on their ability to distinguish between bacteria and viruses and understanding of concepts based on the written and oral presentation.
For the lab, students formulate a hypothesis and procedure in their science notebooks. After the lab activities, students tabulate the collected data and write their own analysis and conclusions.

   Bacteria in the news: Bioremediation is a process by which certain bacteria are used to degrade hazardous substances in the environment. Present and discuss a case study with the class. 

Download Phytoremediation Case Study - Powerpoint or PDF

 SQ3R reading method: http://www.collegeboard.com/student/plan/college-success/26666.html
Contemporary Biology: Exploring the Science of Life (Textbook)