Final answer:
The irregularly-shaped region within a prokaryotic cell holding the genetic material is known as the nucleoid, which is not membrane-bound like a nucleus.
Step-by-step explanation:
The irregularly-shaped region within the cell of a prokaryote that contains all or most of the genetic material is called the nucleoid. Unlike eukaryotic cells, prokaryotes do not have a membrane-bound nucleus. Instead, their single, circular chromosome is found in the central part of the cell, the nucleoid, which is an area of the cytoplasm. This region is densely packed with the DNA and DNA-associated proteins but not bounded by a nuclear membrane as in eukaryotic cells.
Additionally, prokaryotes may contain smaller loops of DNA called plasmids that are capable of being transferred independently of the bacterial chromosome and may carry additional traits such as antibiotic resistance.