Pre-Lab: Controlling Bacterial Growth
Problem How can you determine the effectiveness of an antibiotic?
Materials agar plates, marker, bacterial cultures, sterile glass beads, sterile pipettes, forceps, antibiotic disks, masking tape, metric ruler
Lab Manual Chapter 20 Lab
Skills Focus Observe, Measure, Draw Conclusions
Connect to the Bacteria can be found on and within the human body. Most of these bacteria are harmless and some are even beneficial to humans. But others can cause diseases. These pathogens need to be controlled. Physical removal of bacteria through hand washing is one of the most effective control methods. Proper food storage and preparation is also important, as are the vaccines that have been developed to help the body build up immunity to specific bacterial diseases.
What happens if a person does develop a bacterial infection? Then doctors use drugs, such as antibiotics, to fight the infection. These drugs are designed to kill bacteria but not human cells. In this lab, you will compare the ability of two antibiotics to control the growth of two different types of bacteria.
Review What happens to a bacteria cell after it has grown to nearly double its size? What is this process called?
Explain How is genetic diversity increased in populations of bacteria?
Review What are the two general ways that bacteria can cause disease?
Preview the procedure in the lab manual.
Relate Cause and Effect How will you know whether an antibiotic is able to control the growth of bacteria?
Design an Experiment Why is it important to leave space between the disks on the agar plates?
Control Variables Why must you avoid direct contact between your hands and the antibiotic disks?
Visit Chapter 20 online to test yourself on chapter content and to find activities to help you learn.
Untamed Science Video Join the Untamed Science crew as they fire up the microscopes for a look at bacteria and all the ways they are good for us.
Art in Motion View a short animation of prion infection and see how misfolded proteins interact with normal proteins.
Art Review Review your understanding of the structure and classification of prokaryotes.
InterActive Art Build your understanding of lytic and lysogenic cycles.
Data Analysis Analyze data on MRSA and identify whether the increase in prevalence is due to increased spread, virulence, or simply increased accuracy of diagnoses.
Visual Analogy Compare an old west outlaw taking over a town to a lytic infection.