The primary difference between protists and monerans is that protists are eukaryotic while monerans are prokaryotes. Protists, such as amoebae, are thus more closely related to humans than they are to monerans, such as bacteria.
Monerans and protists are both single-celled organisms, but their similarities largely end at the level of gross anatomy. Monera is a group that includes all true bacteria, while the Kingdom Protista contains single-celled algae, amoebae and paramecia. Protists have relatively simple exterior membranes and equally simple, or absent, cell walls. Monerans have chemically complex cell walls and, with very few exceptions, do not possess the cilia, flagella or pseudopodia common among protists. Protists have discrete cell nuclei that contain linear-oriented DNA organized into multiple chromosomes. Monerans have no nucleus, and their DNA is arranged as a single ring-shaped chromosome. Protists, as is true of all eukaryotes, carry out protein synthesis with the aid of distinct cellular components called organelles, which monerans completely lack. Protists may reproduce sexually or asexually, depending on species and the environment, while monerans generally reproduce asexually via binary fission. Monera is by far the largest and most diverse kingdom of life, while the protists maintain a relative similarity in chemistry, anatomy and behavior.