Prokaryotic Cells

Definition

Prokaryotic cells are simple, single-celled organisms that lack a nucleus and other membrane-bound organelles. They are characterized by their small size, typically ranging from 0.1 to 5.0 micrometers, and include bacteria and archaea. The absence of a nucleus means that their genetic material is found in a region called the nucleoid, which is not enclosed by a membrane, leading to distinct cellular processes compared to eukaryotic cells.

5 Must Know Facts For Your Next Test

1. Prokaryotic cells reproduce primarily through binary fission, a simple process where a single cell divides into two identical daughter cells.
2. They possess ribosomes for protein synthesis, but these ribosomes are smaller than those found in eukaryotic cells.
3. Many prokaryotic cells have a protective cell wall made of peptidoglycan, which provides structural support and shape.
4. Prokaryotes can have plasmids—small, circular DNA molecules separate from chromosomal DNA that can carry genes for antibiotic resistance or other traits.
5. These cells exhibit metabolic diversity, allowing them to thrive in various environments by utilizing different energy sources like sunlight or organic compounds.

Review Questions

• How do prokaryotic cells differ from eukaryotic cells in terms of structure and function?
  • Prokaryotic cells differ from eukaryotic cells mainly in their lack of a nucleus and membrane-bound organelles. While eukaryotic cells have complex structures with organized compartments for various functions, prokaryotic cells have a simpler structure, with their genetic material located in the nucleoid region. Additionally, prokaryotes reproduce through binary fission rather than mitosis or meiosis seen in eukaryotes.
• Discuss the significance of plasmids in prokaryotic cells and how they contribute to antibiotic resistance.
  • Plasmids are small, circular DNA molecules found in many prokaryotic cells that can replicate independently of chromosomal DNA. They often carry genes that provide advantages to bacteria, such as antibiotic resistance. When bacteria exchange plasmids through horizontal gene transfer, they can quickly spread these resistance traits among populations, making it challenging to treat infections caused by resistant strains.
• Evaluate the role of prokaryotic cells in ecological systems and their impact on human health.
  • Prokaryotic cells play critical roles in ecological systems by participating in nutrient cycling, such as nitrogen fixation by certain bacteria that convert atmospheric nitrogen into forms usable by plants. This process supports plant growth and overall ecosystem health. However, some prokaryotes can also impact human health negatively; pathogenic bacteria can cause diseases, leading to significant public health challenges. Understanding both their beneficial and harmful roles is essential for managing ecosystems and healthcare.

Related terms

Bacteria: Bacteria are single-celled prokaryotic organisms that are found in various environments and play essential roles in ecosystems, including decomposition and nitrogen fixation.

Archaea: Archaea are a group of prokaryotic organisms that often live in extreme environments, such as hot springs or salt lakes, and have distinct biochemical and genetic characteristics compared to bacteria.

Cell Membrane: The cell membrane is a protective barrier that surrounds prokaryotic cells, controlling the movement of substances in and out of the cell while maintaining homeostasis.