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capsule
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Labeled diagram of a bacillus-shaped bacterial cell showing capsule, cell wall, cell membrane, cytoplasm, nuclear matter, pili, and a single long flagellum extending from one end. Labeled diagram of a bacterial cell showing key structures including capsule, cell wall, plasma membrane, cytoplasm, chromosome, plasmid, ribosomes, mesosome, pili, and long flagella. Illustration comparing three cell types: a round animal cell and an irregularly shaped plant cell, both showing labeled organelles, and an elongated bacteria cell with labeled structures such as flagella and capsule.
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capsule

in prokaryote
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Labeled diagram of a bacillus-shaped bacterial cell showing capsule, cell wall, cell membrane, cytoplasm, nuclear matter, pili, and a single long flagellum extending from one end.
Bacillus-type bacterial cell Schematic drawing of the structure of a typical bacterial cell of the bacillus type.

In prokaryotes, a capsule is a layer of extracellular material, typically composed of polysaccharides, that is tightly attached to the bacterial cell. This capsule can protect the bacterium from being ingested by white blood cells, a process known as phagocytosis, thereby aiding in the cause of disease. For example, the presence of a capsule is crucial for Streptococcus pneumoniae to cause pneumonia. Capsules can also help bacteria avoid dehydration and adhere to surfaces, such as teeth in the case of Streptococcus mutans, which contributes to dental caries. Some bacteria form capsules that enclose them in a biofilm, which can serve various functions depending on the species and its environment.1

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4 Britannica Sources
  1. bacteria - Capsules and slime layers
  2. capsule
  3. capsule
  4. prokaryote: Top Questions

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