Mesosomes

Definition

Mesosomes are invaginations or infoldings of the plasma membrane found in some prokaryotic cells, particularly in bacteria. These structures are thought to increase the surface area for cellular processes and play a role in various functions such as cell division, DNA replication, and energy production. Though their exact function remains debated, they are often associated with the organization of cellular components in prokaryotes.

5 Must Know Facts For Your Next Test

1. Mesosomes were once thought to be essential for respiration and cell division in bacteria, but more recent research suggests they may not have specific functions as once believed.
2. These structures can vary in shape, appearing as tubular or vesicular formations depending on the species of bacteria.
3. Mesosomes are often observed in electron micrographs of bacterial cells, indicating their presence during certain cellular activities.
4. Their formation might be influenced by environmental conditions such as nutrient availability and stress factors.
5. Despite their name suggesting a connection with membranes, mesosomes are generally considered artifacts resulting from the preparation of samples for microscopy rather than distinct functional structures.

Review Questions

• What are mesosomes and how do they contribute to the structure and function of prokaryotic cells?
  • Mesosomes are invaginations of the plasma membrane found in some prokaryotic cells that serve to increase surface area for various cellular processes. They are believed to play a role in important functions like DNA replication and energy production, although their precise role remains unclear. By providing additional surface area, mesosomes may help facilitate cellular activities critical for the survival and reproduction of prokaryotic organisms.
• Discuss the significance of mesosomes in relation to prokaryotic cell division and any controversies surrounding their function.
  • Mesosomes have traditionally been thought to assist in prokaryotic cell division by anchoring chromosomal DNA during the process. However, there is ongoing debate regarding their actual function, as some studies suggest they might not have a specific role at all and could instead be artifacts from sample preparation. This controversy highlights the need for further research to clarify whether mesosomes are essential structures or merely remnants of cellular preparation techniques.
• Evaluate the implications of considering mesosomes as artifacts rather than functional structures within prokaryotic cells and how this affects our understanding of bacterial physiology.
  • If mesosomes are considered artifacts rather than functional structures, it could significantly alter our understanding of bacterial physiology and cellular organization. This reevaluation would suggest that prokaryotic cells may utilize different mechanisms for processes like respiration and DNA replication than previously thought. It challenges scientists to explore alternative explanations for the roles traditionally attributed to mesosomes, potentially leading to new insights into bacterial adaptability and survival strategies under various environmental conditions.

Related terms

prokaryotes: Organisms characterized by the absence of a membrane-bound nucleus and organelles, including bacteria and archaea.

plasma membrane:

The selective barrier that surrounds all cells, regulating the passage of substances in and out of the cell.

nucleoid:

The region within a prokaryotic cell where the circular DNA is located, not enclosed by a membrane.