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Ch. 11 - Characterizing and Classifying Prokaryotes
Bauman - Microbiology with Diseases by Taxonomy 6th Edition
Bauman6th EditionMicrobiology with Diseases by TaxonomyISBN: 9780134832302Not the one you use?Change textbook
All textbooksBauman 6th EditionCh. 11 - Characterizing and Classifying ProkaryotesProblem 1
Chapter 11, Problem 1

Label the shapes of these prokaryotic cells.


a. ___________ <IMAGE>
b. ___________ <IMAGE>
c. ___________ <IMAGE>
d. ___________ <IMAGE>
e. ___________ <IMAGE> stiff
f. ___________ <IMAGE> flexible
g. ___________ <IMAGE>

Verified step by step guidance
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Step 1: Understand the common shapes of prokaryotic cells. The main shapes include cocci (spherical), bacilli (rod-shaped), spirilla (spiral-shaped with rigid structure), spirochetes (spiral-shaped but flexible), vibrio (comma-shaped), and filamentous forms.
Step 2: For each image, observe the overall shape of the cell. Determine if the cell is spherical, rod-like, spiral, comma-shaped, or filamentous. Pay attention to whether the spiral shape is rigid or flexible, as this distinguishes spirilla from spirochetes.
Step 3: Match the observed shape to the correct term. For example, if the cell is round, label it as 'coccus'; if rod-shaped, label it as 'bacillus'; if spiral and stiff, label it as 'spirillum'; if spiral and flexible, label it as 'spirochete'; if comma-shaped, label it as 'vibrio'.
Step 4: For any filamentous or unusual shapes, consider if the cells form chains or filaments, which can be characteristic of certain bacteria like filamentous cyanobacteria or actinomycetes.
Step 5: Write down the appropriate shape name next to each image based on your observations and the definitions of prokaryotic cell shapes.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Prokaryotic Cell Shapes

Prokaryotic cells exhibit distinct shapes that help in their identification and classification. The main shapes include cocci (spherical), bacilli (rod-shaped), and spirilla (spiral-shaped). Recognizing these shapes is fundamental for understanding bacterial morphology and its implications in microbiology.
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Cell Wall Structure and Rigidity

The rigidity or flexibility of prokaryotic cells is influenced by their cell wall composition. Gram-positive bacteria have thick peptidoglycan layers providing stiffness, while Gram-negative bacteria have thinner walls and an outer membrane, often resulting in more flexible shapes. This structural difference affects cell shape and staining properties.
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Motility and Shape Variations in Prokaryotes

Some prokaryotes have flexible shapes, such as spirochetes, which enable motility through twisting motions. The flexibility or stiffness of the cell shape relates to their ecological roles and movement mechanisms. Understanding these variations aids in identifying bacteria and their functional adaptations.
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Related Practice
Textbook Question

Whereas the first edition of Bergey’s Manual relied on morphological and biochemical characteristics to classify microbes, the new edition focuses on ribosomal RNA sequences. List several other criteria for grouping and classifying bacteria.

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Textbook Question

For each of the following statements that is true, write “true” in the blank. For each statement that is false, write the word(s) that should be substituted for the underlined word(s) to make the statement correct.

__________ All prokaryotes reproduce sexually.

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Textbook Question

The type of reproduction in prokaryotes that results in a palisade arrangement of cells is called ___________ .


a. pleomorphic division

b. endospore formation

c. snapping division

d. binary fission

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