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Biology LibreTexts

2.4A: Cytoplasm

Skills to Develop

  1. Define the following:
    1. exoenzymes
    2. endoenzymes.
    3. cytosol
  2. State the primary function of the bacterial cytoplasm.
  3. Define the following:
    1. metabolism
    2. catabolic reactions
    3. anabolic reactions.

We will now look at the bacterial cytoplasm. In bacteria, the cytoplasm refers to everything enclosed by the cytoplasmic membrane. About 80% of the cytoplasm of bacteria is composed of water. Within the cytoplasm can be found nucleic acids (DNA and RNA), enzymes and amino acids, carbohydrates, lipids, inorganic ions, and many low molecular weight compounds. The liquid component of the cytoplasm is called the cytosol. Some groups of bacteria produce cytoplasmic inclusion bodies that carry out specialized cellular functions.

Functions

While bacteria secrete exoenzymes to hydrolize macromolecules into smaller molecules capable of being transported across the cytoplasmic membrane, the cytoplasm is the site of most bacterial metabolism. This includes catabolic reactions in which molecules are broken down in order to obtain building block molecules for more complex cellular molecules and macromolecules, and anabolic reactions used to synthesize cellular molecules and macromolecules. The chemical reactions occuring within the bacterium are under the control of endoenzymes.

The various structurural filaments in the cytoplasm collectively make up the prokaryotic cytoskeleton. Prokaryotic cells possess analogs for all of the cytoskeletal proteins found in eukaryotic cells, as well as cytoskeletal proteins with no eukaryotic homologues. Cytoskeletal filaments play essential roles in determining the shape of a bacterium (coccus, bacillus, or spiral) and are also critical in the process of cell division by binary fission and in determining bacterial polarity.

Summary

  1. In bacteria, the cytoplasm refers to anything enclosed by the cytoplasmic membrane.
  2. The liquid portion of the cytoplasm is called the cytosol.
  3. The cytoplasm is the site of most bacterial metabolism.
  4. During catabolic reactions larger molecules are broken down to obtain cellular building block molecules and energy; during anabolic reactions cellular molecules and macromolecules are synthesized.

Questions

Study the material in this section and then write out the answers to these questions. Do not just click on the answers and write them out. This will not test your understanding of this tutorial.

  1. Matching:

    _____ Enzymes that are secreted and function outside the bacterium. (ans)

    _____ Enzymes that function within the bacterium. (ans)

    _____ All of the chemical reactions carried out by a bacterium. (ans)

    _____ Chemical reactions in which more complex molecules are synthesized. (ans)

    _____ Chemical reactions in which more complex molecules are broken down into smaller, more simple molecules. (ans)

    1. Metabolism
    2. Catabolic reactions
    3. Anabolic reactions
    4. Exoenzymes
    5. Endoenzymes
  2. State the primary function of bacterial cytoplasm. (ans)

Contributors

  • Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS)