Prokaryote

A Prokaryote is a type of cell that does not have a nucleus or any other membrane-bound organelles. This means that all the genetic material is freely floating in the cytoplasm. Prokaryotes are usually single-celled organisms and are classified into two domains: Bacteria and Archaea.

Characteristics

Prokaryotes are typically much smaller than eukaryotic cells. They have a variety of shapes, the most common of which are spherical (coccus), rod-shaped (bacillus), and spiral (spirillum). Some prokaryotes have flagella or pili for locomotion.

Genetics

Prokaryotes have a single, circular chromosome that is not contained within a nucleus. They also have plasmids, which are small, circular pieces of DNA that can be transferred between cells.

Reproduction

Prokaryotes reproduce asexually through a process called binary fission. Some prokaryotes can also exchange genetic material through a process called horizontal gene transfer.

Ecology

Prokaryotes are found in nearly every environment on Earth. They play many important roles in ecosystems, such as decomposing organic material and fixing nitrogen.

Classification

Prokaryotes are divided into two domains: Bacteria and Archaea. Bacteria are the most diverse and well-known group of prokaryotes. Archaea were originally classified as bacteria, but they are genetically and biochemically distinct.

Health and disease

While many prokaryotes are beneficial, some can cause diseases. These pathogenic prokaryotes are a major cause of human illness.

See also

• Eukaryote
• Cell biology
• Microbiology

• 
  Prokaryote cell structure
• 
  Bacterial conjugation
• Primordial biogenesis
  Primordial biogenesis
• 
  A novel representation of the tree of life
• Phylogenetic tree of Prokaryota
  Phylogenetic tree of Prokaryota