What are the characteristics of prokaryotic cells?

Prokaryotic cells lack a true membrane-bound nucleus; their genetic material (DNA) is located in a region called the nucleoid, which is not separated from the rest of the cell by a membrane.

They do not possess membrane-bound organelles such as mitochondria, endoplasmic reticulum, or Golgi apparatus; all cellular processes occur in the cytoplasm or at the cell membrane.

Their cell walls are typically composed of peptidoglycan (in bacteria), which provides structural support and shape; however, Archaea possess cell walls made of other polymers such as pseudopeptidoglycan.

Prokaryotes are usually unicellular organisms, though some may form colonies or biofilms for survival and cooperative functions.

They reproduce asexually, primarily through binary fission, a simple process of cell division where the DNA is replicated and the cell splits into two identical daughter cells.

Their genetic material is usually a single, circular double-stranded DNA molecule; plasmids (small circular DNA fragments) may also be present and can carry genes for antibiotic resistance or other adaptive traits.

Ribosomes in prokaryotic cells are of the 70S type (composed of 50S and 30S subunits), which are smaller than the 80S ribosomes found in eukaryotic cells.

The plasma membrane performs many functions typically carried out by organelles in eukaryotic cells, such as energy production (via respiratory enzymes or photosynthetic complexes).

Some prokaryotes possess specialized external structures such as:

• Flagella for locomotion

• Pili or fimbriae for attachment and conjugation (DNA transfer)

• Capsules or slime layers that offer protection and help in adherence to surfaces

Metabolically, prokaryotes are extremely diverse, including aerobic and anaerobic respiration, fermentation, photosynthesis (in cyanobacteria), and chemosynthesis.

They are found in a wide range of environments, including extreme conditions like high temperature, salinity, acidity, and pressure, which is especially true for Archaea.

Prokaryotic cells are generally smaller in size (typically 0.1–5.0 μm in diameter) compared to eukaryotic cells.

Examples of prokaryotic organisms include bacteria and archaea, which are classified under the domains Bacteria and Archaea, respectively.