Archaea and bacteria are prokaryotes that lack cell nuclei and membrane-bound organelles, while protists are eukaryotes that possess both of these features. Archaea and bacteria are always single celled, while a small number of protists are multicellular organisms.Know More
Archaea and bacteria both store their DNA in rings called plasmids, and both are surrounded by cell walls. Protists store their DNA inside a defined cell nucleus. Some protist groups, such as algae, possess cell walls; other groups, such as the animal-like protozoa, do not have cell walls.
While all archaea and bacteria are single-celled organisms, some protists are multicellular organisms. Multicellular protists include kelp and other large brown algae species; all other species of protists are single celled. All three groups include varied species that obtain energy in diverse ways: through photosynthesis, through consuming chemicals and through consuming other organisms.
Most archaea consume chemicals, but some species can switch to photosynthesis when necessary. All species of algae obtain their energy via photosynthesis, but animal and fungus-like protists consume other organisms for food. Bacteria are represented in all three groups and have a more diverse range of habitats than archaea or protists. Archaea have the smallest habitat of the three groups, living in extreme environments that cannot support other life.Learn more about Biology
Common examples of multicellular protists include brown algae, green algae, red algae and slime molds. Algae are classified as plant-like protists, while slime molds are categorized as fungus-like protists.Full Answer >
Prokaryotes do not have mitochondria. A prokaryote is a cell that does not contain membrane-bound structures called organelles. A mitochondrion is an organelle, but because prokaryotes do not have organelles, they do not have mitochondria.Full Answer >
Some harmful protists include plasmodium, gregarines, haemosporidia and coccidians. Others include babesia, toxoplasma, adeleorina and some forms of amoeba. Some of these protists are parasites on invertebrates such as gastropods while others are parasites on vertebrates such as humans.Full Answer >
Protists are single-celled organisms that spread disease, either through direct infection or via toxins excreted into food and water supplies. Protist infections cause gastrointestinal and nervous system diseases, as well as skin and lung conditions.Full Answer >