Structure and Function of Prokaryotes

Prokaryotes are simple unicellular organisms in which the genetic material is not enclosed in a cell nucleus. They are considered to be the first forms of life on earth. The actual word comes from the Greek language, where pro = before and karyo = cell.

General Structure of Prokaryocytes

 * small cells (1-5 μm);
 * hereditary material (DNA) is not enclosed within nuclear membrane;
 * no histones (specific basic proteins) bound to their DNA;
 * no membrane bound organelles (eg mitochondria, chloroplasts);
 * no distinct nucleus, no chromosomes, no centrioles, no microtubules;
 * prokaryotes are divided into 2 domains: Bacteria and Archaea.

Bacteria

 * Structure:


 * Functions:
 * 1) Bacteria are responsible for decaying and recycling organic material in the soil (producing fossil fuels) & sewage deposits.
 * 2) Some bacteria are parasitic, causing disease to host. Bacterial diseases of man can spread in a variety of ways including direct contact, contamination of food & water, eg Tuberculosis (mycobacterium tuberculosis)
 * 3) Some have symbiotic relationship with host eg helping digestion
 * 4) Bacteria are also used by humans in several ways: food production eg cheese, alcohol, yogurt; detergents (especially preferred those which withstand high temperatures); use in research, especially in genetics; and in making antibiotics

Related articles

 * Prokaryotic Chromosomes