Covalently closed single-stranded circular RNA molecule with a size of 246~399nt (nucleotides)

Defective viroids encapsulated in true virus particles

Generally composed only of naked RNA (300~400 nucleotides) or DNA

Non-cellular organisms, mainly composed of nucleic acids (DNA or RNA) and protein shells.

A cell-free structure composed mainly of nucleic acids and protein shell. Some viruses also have an envelope, and there may be spikes and other structures on the envelope.

10~300 nanometer (nm) range, the minimum is about 10nm (such as parvovirus), the maximum is 300nm (such as poxvirus)

protein virus

The diameter of type I fiber is 11~14nm, and the diameter of type II fiber is 27~34nm.

The smallest prokaryotic microorganism that has no cell wall, is highly pleomorphic, and can be cultured and proliferated in artificial media

Small size, 0.1~0.3 microns (μm)

Prokaryotic cell-type microorganisms that can pass through bacterial filters, have unique development cycles, and are strictly intracellular parasitists. They mainly parasitize the urogenital tract system of the human body and can cause a variety of diseases.

The normal range is generally 0.3~0.5μm

Special group capable of forming branching hyphae and conidia

The hyphae are slender, with a width close to that of rod-shaped bacteria, about 0.2~1.2μm

Microorganisms that are elongated, soft, and curved in a spiral shape. They are capable of locomotion, usually through longitudinal axonemes. Spirochetes are widely distributed in nature, including aquatic environments, soil, and animals. Among them, some spirochetes are pathogenic to humans.

The total length is 3~500μm, and the smallest is 0.2~0.3μm.

A large category of prokaryotes, with shapes including spheres, rods, spirals, arcs, lines, etc.

There is no formed nucleus, only nucleoids. Cell walls have various components, some containing peptidoglycan and some containing other components. Reproduce by division.

Generally the diameter is around 100nm

An individual composed of single cells, without real tissues, organs, or systems

Single-celled animals, ranging in size from a few microns to dozens of microns, generally 30~300μm

A large group of eukaryotes that is independent of animals, plants, and other eukaryotes and forms its own kingdom.

It has a true nucleus, no chlorophyll, and the main component of the cell wall is chitin or cellulose or both. The vegetative body is mycelium, which can branch and form colonies. Spores are produced through asexual and sexual reproduction.

Eukaryotes, sizes vary by species but are usually larger than microorganisms such as bacteria and viruses

Aquatic, non-vascular, capable of photosynthesis.

Eukaryotes, size varies by species, single-celled algae are generally smaller, multi-celled algae may be larger