Differences between Celula-Eucariota-Procariota
Contents
Comparison Article
Differences between prokaryotic and eukaryotic cells are a primary focus in the study of cell biology. All living organisms are composed of one of these two cell types. Prokaryotes, which include the domains Bacteria and Archaea, are characterized by their simple structure and lack of a membrane-bound nucleus. Eukaryotes, encompassing animals, plants, fungi, and protists, possess a complex internal structure with specialized compartments called organelles.
Comparison of prokaryotic and eukaryotic cells
The primary distinction between these two groups is the organization of their genetic material and the presence of internal membranes.
Comparison table
| Feature | Prokaryotic Cells | Eukaryotic Cells |
|---|---|---|
| Nucleus | Absent; DNA is in the nucleoid region | Present; DNA is enclosed in a nuclear envelope |
| DNA structure | Single circular chromosome | Multiple linear chromosomes |
| Membrane-bound organelles | Absent | Present (e.g., mitochondria, chloroplasts, Golgi apparatus) |
| Cell size | Generally small (0.1–5.0 µm) | Generally larger (10–100 µm) |
| Ribosomes | Smaller (70S) | Larger (80S) |
| Cell wall | Usually present (contains peptidoglycan in bacteria) | Present in plants and fungi (cellulose or chitin); absent in animals |
| Reproduction | Binary fission | Mitosis and meiosis |
| Cytoskeleton | Simple or absent | Complex and present |
Structural organization
Eukaryotic cells contain a variety of membrane-bound organelles that allow for the compartmentalization of chemical reactions. For example, mitochondria are the site of aerobic respiration, while lysosomes contain digestive enzymes. This compartmentalization enables eukaryotic cells to grow larger than prokaryotic cells by maintaining efficient transport and communication within the cell.
In contrast, prokaryotic cells lack these internal compartments. Metabolic processes, such as respiration and photosynthesis, occur across the plasma membrane. While prokaryotes lack a nucleus, they contain a nucleoid, an irregularly shaped region where the circular DNA is located.
Genetic material and protein synthesis
The storage and expression of genetic information differ significantly between the two cell types. Eukaryotic DNA is associated with proteins called histones, which help package the DNA into chromatin within the nucleus. Prokaryotic DNA is generally "naked," meaning it is not associated with histones, although some archaea possess histone-like proteins.
Ribosomes are responsible for protein synthesis in both cell types, but they differ in size and composition. Prokaryotic ribosomes are 70S, composed of a 30S and a 50S subunit. Eukaryotic ribosomes are 80S, composed of a 40S and a 60S subunit. This difference is utilized in medicine, as some antibiotics specifically target 70S ribosomes to kill bacteria without affecting the host's eukaryotic cells.
Evolutionary relationship
The endosymbiotic theory provides an explanation for the origin of eukaryotic cells. This theory suggests that mitochondria and chloroplasts were once free-living prokaryotic organisms that were engulfed by a larger host cell. Over time, these engulfed cells became permanent parts of the host, leading to the development of complex eukaryotic organisms. Evidence for this theory includes the fact that mitochondria and chloroplasts contain their own circular DNA and 70S ribosomes, similar to modern bacteria.
References
- Campbell, N. A., & Reece, J. B. (2020). Biology (12th ed.). Pearson.
- Lodish, H., et al. (2016). Molecular Cell Biology (8th ed.). W. H. Freeman.
- Sapp, J. (2005). "The Prokaryote-Eukaryote Dichotomy: Meanings and Mythology". Microbiology and Molecular Biology Reviews. **69** (2): 292–305. doi:10.1128/MMBR.69.2.292-305.2005.
