A specialized membranous structure in a prokaryotic cell which helps in cell wall formation, DNA replication and respiration is:

Solution:

Mesosomes are specialized differentiated forms of the cell membrane found in prokaryotic cells. They are invaginations of the plasma membrane into the cytoplasm. These structures are involved in various functions such as cell wall formation, DNA replication and distribution to daughter cells, respiration, secretion processes, and increasing the surface area of the plasma membrane and enzymatic content.

Chromatophores are pigment-containing and light-reflecting cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans, and cephalopods. In some prokaryotes (like cyanobacteria), they refer to membrane systems with photosynthetic pigments, but they are not involved in all the listed functions.

Cristae are the folds of the inner membrane of mitochondria, which are found in eukaryotic cells, not prokaryotic cells. They increase the surface area for cellular respiration.

Endoplasmic Reticulum (ER) is a network of membranes found in eukaryotic cells, involved in protein and lipid synthesis, and is absent in prokaryotic cells.