5 Microbial Physiology Module 5: Flagella

A type of flagellar arrangement wherein two or more flagella are at one or both poles of the bacterium

• Lophotrichous

• Amphitrichous

• Monotrichous

• Peritrichous

Answer explanation

Answer is A. Lophotrichous flagellar arrangement describes two or more flagella at one or both poles such as in Helicobacter pylori as seen in the scanning electron micrograph.

Reference:

Madigan, M. T., Bender, K. S., Buckley, D. H., Sattley, W. M., & Stahl, D. A.

(2018). Brock biology of microorganisms. Pearson Higher Education.

https://microbesinfo.com/wp-content/uploads/2017/07/OSC_Microbio_03_03_FlagellaAr.jpg

All are alternative forms of motility for bacteria except:

• Gliding movement

• F Pilus

• Axial filaments

• Rachet structures

• Contractile cytoskeleton

Answer explanation

Answer is B. Gliding movement, axial filament, and rachet structure are forms of bacterial motility. F pilus of E. coli is a conjugative pilus for bacterial conjugation. 

Reference:

Madigan, M. T., Bender, K. S., Buckley, D. H., Sattley, W. M., & Stahl, D. A.

(2018). Brock biology of microorganisms. Pearson Higher Education.

The bacterial flagellum is assembled in this order:

• Cap > Hook > Junction > Filament

• Rings > Junction > Hook > Filament

• Rod > Hook > Junction > Filament

• Hook > Rod > Junction > Filament

Answer explanation

Answer is C.  Bacterial flagellar synthesis commences in an “inside out” direction. First, the MS ring, P ring and L ring are assembled followed by the formation of the early hook, hook-filament junction and finally the elongation of the filament.

Reference:

Madigan, M. T., Bender, K. S., Buckley, D. H., Sattley, W. M., & Stahl, D. A.

(2018). Brock biology of microorganisms. Pearson Higher Education.

White, D., Drummond, J., Drummond, J. T., & Fuqua, C. (2012). The physiology

and biochemistry of prokaryotes. Oxford University Press, USA.

The chemotaxis protein responsible for constantly methylating the methyl-accepting chemotaxis protein (MCP) is:

• CheA

• CheY

• CheB-P

• CheB

• CheR

Answer explanation

Answer is E. In the MCP, the methyl groups are added by the methyl transferase CheR and are removed by the phosphorylated methylesterase Che B-P.  

Reference:

Madigan, M. T., Bender, K. S., Buckley, D. H., Sattley, W. M., & Stahl, D. A.

(2018). Brock biology of microorganisms. Pearson Higher Education.

White, D., Drummond, J., Drummond, J. T., & Fuqua, C. (2012). The physiology

and biochemistry of prokaryotes. Oxford University Press, USA.

A counterclockwise rotation of a peritrichous, bundled flagella will:

• Cause a forward motion

• Cause a tumbling motion 

• Stop and reorient the cell

• None of the above

Answer explanation

Answer is A. Forward motion is imparted by all peritrichous flagella rotating counterclockwise (CCW) in a bundle.

Reference:

Madigan, M. T., Bender, K. S., Buckley, D. H., Sattley, W. M., & Stahl, D. A.

(2018). Brock biology of microorganisms. Pearson Higher Education.