Microbiology - Ch. 4 Prokaryotic and Eukaryotic Cell Anatomy - flashcards

How is bacterial size measured, and why does it matter?

Measured in microns (μm) — e.g., ~2.0 μm diameter × ~8 μm length. Important for identification purposes.

Monomorphic vs. pleomorphic — definitions?

Monomorphic = one shape present in visual field, all bacteria are identical (majority of bacteria).

Pleomorphic = many/several shapes present in visual field, meaning more than one type of bacteria is present.

What are the 3 basic shapes of bacteria?

Coccus (round/spherical).

Bacillus (rod-shaped).

Spiral (3 types — vibrio, spirillum, spirochete).

What is a coccobacillus?

An "oval" shaped bacterium — intermediate form of bacillus

What does "vibrio" shape look like?

"Comma" shaped — short curved rod

What do all three spiral bacteria types (vibrio, spirillum, spirochete) have in common?

They are all motile

What's the singular form of "spirilla"?

Spirillum (spirilla = plural)

Spirillum moves via external flagella — spirochete moves via internal flagella. What's the key visual/structural difference?

Spirillum's flagellum sits outside the cell body (external). Spirochete's flagellum (endoflagellum) is located inside the bacterium, between the cell wall layers.