Question

Do prokaryotes have a nucleus?

Answer 1

Hint: Prokaryotes are the unicellular organisms and are the most primitive life forms on earth. Prokaryotes (‘pro’ means old and ‘karyon’ means nucleus). Prokaryotes lack the membrane bound cell organelles and a well-defined nucleus. They do not have a nucleus with an envelope called a nuclear membrane and therefore it is called a nucleoid. All membrane bound cell organelles, e.g., lysosomes, mitochondria, spherosomes, golgi bodies, plastids, etc. are absent in a prokaryotic cell.

Complete answer:
Prokaryotes lack the membrane bound cell organelles and a well-defined nucleus. DNA bundles together in a region known as the nucleoid in prokaryotic cells. The nucleoid (nucleus-like) is an irregularly shaped region in the prokaryotes. The nucleoid contains all or most of the genetic material. The chromosome is circular in shape and its length is very large compared to the cell dimensions needing it to be compacted in order to get fit into the prokaryotic cell. As in eukaryotic cells, the nucleus of a prokaryotic cell is not surrounded by a nuclear membrane. Instead, the nucleoid is formed by condensation and functional arrangement with the help of chromosomal architectural proteins and RNA molecules as well as DNA supercoiling. The length of a genome varies widely and a cell may contain multiple copies of it. A highly resolved structure of a bacterial nucleoid is not known yet, however key features of it have been researched in Escherichia coli as a model organism.

Note:
A prokaryotic cell does not have distinct cellular regions. Other characteristics of prokaryotes are: Mitotic spindle is absent. Gametes are absent. They have the ability to convert nitrogen into ammonia. Reproduction is by asexual methods. Genetic material is not organized into a nucleus, DNA is naked, i.e., not associated with histone proteins and it lies coiled inside the cytoplasm. Their flagella are single stranded, if present. These are the most abundant microorganisms that occur almost everywhere.