Bacteria tumble when they are not moving in a significant forward direction but are repositioning their direction to move. When tumbling, the flagella are moving clockwise and are splayed out.

University of Wisconsin - Madison

There are two types of bacterial movements that are facilitated by flagella: 
- Running
- Tumbling

Directional Movement of Bacteria

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Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

Microbiology is produced through a collaborative publishing agreement between OpenStax and the American Society for Microbiology Press. The book aligns with the curriculum guidelines of the American Society for Microbiology.

OpenStax Microbiology Textbook

Bacteria may run towards food sources or away from toxins. When running, flagella rotate counterclockwise so that the bacteria moves forward. 

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