Prokaryotic Cells

Definition

Prokaryotic cells are unicellular organisms that lack a true nucleus and membrane-bound organelles, distinguishing them from eukaryotic cells. These cells are typically smaller and simpler in structure, with their genetic material organized in a single circular chromosome located in the nucleoid region. Prokaryotic cells include bacteria and archaea, and they play vital roles in various ecological processes and human health.

5 Must Know Facts For Your Next Test

1. Prokaryotic cells are generally much smaller than eukaryotic cells, typically ranging from 0.1 to 5.0 micrometers in diameter.
2. They reproduce asexually through a process called binary fission, where one cell divides into two identical daughter cells.
3. The cell wall composition varies between different types of prokaryotes; for example, bacteria have peptidoglycan in their walls, while archaea have different polysaccharides.
4. Prokaryotic cells can have various shapes, including cocci (spherical), bacilli (rod-shaped), and spirilla (spiral), which can influence their behavior and ecological roles.
5. Some prokaryotic cells possess flagella or pili that assist in movement and attachment to surfaces, enhancing their ability to thrive in diverse environments.

Review Questions

• Compare and contrast prokaryotic cells with eukaryotic cells in terms of structure and function.
  • Prokaryotic cells differ significantly from eukaryotic cells in both structure and function. Prokaryotic cells lack a true nucleus; instead, their genetic material is found in the nucleoid region. They also do not have membrane-bound organelles like mitochondria or the endoplasmic reticulum, which are present in eukaryotes. Functionally, prokaryotes are often more efficient in metabolic processes due to their simpler structure and smaller size, allowing them to reproduce quickly and adapt rapidly to environmental changes.
• Discuss the role of plasmids in prokaryotic cells and how they can impact antibiotic resistance.
  • Plasmids are small, circular DNA molecules that exist independently within prokaryotic cells, often carrying genes that provide advantages under specific conditions. In the context of antibiotic resistance, plasmids can harbor genes that enable bacteria to resist the effects of antibiotics, allowing them to survive and proliferate despite the presence of these drugs. The transfer of plasmids between bacteria through processes like conjugation facilitates the rapid spread of resistance traits, posing significant challenges for treatment strategies against bacterial infections.
• Evaluate the ecological significance of prokaryotic cells, focusing on their roles in nutrient cycling and human health.
  • Prokaryotic cells play crucial ecological roles, particularly in nutrient cycling, where they contribute to processes such as nitrogen fixation and decomposition. Their ability to break down complex organic materials helps recycle nutrients back into ecosystems, maintaining soil health and supporting plant growth. Additionally, certain prokaryotes are essential for human health; for instance, gut microbiota aids digestion and synthesizes vitamins. However, pathogenic prokaryotes can cause diseases, highlighting the duality of their impact on human health and the environment.

Related terms

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

Plasmids: Small, circular DNA molecules found in prokaryotic cells that can replicate independently of chromosomal DNA and often carry genes for antibiotic resistance.

Cell Wall: A rigid outer layer that surrounds the cell membrane of many prokaryotic cells, providing structural support and protection.