A student was memorizing the arrangements of bacteria and noticed that there are more arrangements for cocci than for bacilli. Why might this be so?

Verified step by step guidance

Step 1: Understand the basic shapes of bacteria involved—cocci are spherical, while bacilli are rod-shaped. This difference in shape influences how they can physically arrange themselves.

Step 2: Recognize that cocci, being spherical, can attach to each other in multiple planes and directions, allowing for diverse arrangements such as pairs (diplococci), chains (streptococci), clusters (staphylococci), and tetrads.

Step 3: Consider that bacilli, due to their rod shape, tend to align end-to-end or side-by-side, which limits their possible arrangements mostly to chains or palisades, resulting in fewer distinct patterns.

Step 4: Reflect on how the three-dimensional geometry of cocci allows for more complex and varied groupings compared to the more linear or planar groupings of bacilli.

Step 5: Conclude that the greater number of arrangements for cocci arises from their spherical shape enabling multiple modes of cellular adhesion and spatial organization, unlike the more restricted rod-shaped bacilli.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

Was this helpful?

Key Concepts

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

Bacterial Morphology

Bacterial morphology refers to the shape and size of bacteria, with common types including cocci (spherical) and bacilli (rod-shaped). The shape influences how bacteria group and arrange themselves, affecting their colony structure and identification.

Arrangements of Cocci

Cocci can form various arrangements such as diplococci (pairs), streptococci (chains), staphylococci (clusters), tetrads (groups of four), and sarcinae (cubical packets). This diversity arises from their spherical shape and the way they divide in multiple planes.

Arrangements of Bacilli

Bacilli typically arrange in fewer patterns like single rods, diplobacilli (pairs), or streptobacilli (chains). Their rod shape limits the planes of division, resulting in fewer possible arrangements compared to cocci.

Recommended video:

Guided course

03:56

Bacilli Bacterial Cell Arrangements

Related Practice

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.

__________ Halophiles inhabit extremely saline habitats, such as the Great Salt Lake.

views

Textbook Question

How is Agrobacterium used in recombinant DNA technology?

views

Textbook Question

Compare and contrast bacterial and archaeal cells.

views

Textbook Question

Which genus is the most common anaerobic human pathogen?

a. Bacteroides

b. Spirochetes