Question

multiple choice question
the bacterial cell surface layer illustrated here is termed a(n) ______.
options: s - layer, glycocalyx, capsule, cell envelope

Explanation:

To determine the bacterial cell surface layer, we analyze each option:

• S - layer: It is a regularly structured, proteinaceous surface layer found in many bacteria, often with a crystalline appearance at the nanoscale (as suggested by the 100 nm scale bar here).
• Glycocalyx: A general term for the polysaccharide - rich layer outside the cell, but it is not as structured at the nanoscale as an S - layer.
• Capsule: A type of glycocalyx, usually a well - defined, thick polysaccharide layer for protection, not typically with the fine, regular structure seen here.
• Cell envelope: Encompasses the cell membrane, cell wall, etc., not a specific surface layer as depicted.

The structure in the image, with the 100 nm scale and the regular, fine - grained appearance, is consistent with an S - layer.

Answer:

A. S - layer