Similarities & Differences Between Fungi & Monera

In 1735, Carl Linnaeus published his book "Systema Naturae." In this book, Linnaeus divided known life forms into plants and animals. He classified fungi as forms of plants and ignored the microscopic observations of Robert Hooke (1635-1703) and Antony van Leeuwenhoek (1632-1723).

Since then, based on the characteristics of fungi and bacteria, scientists have separated fungus and bacteria into their own kingdoms.

Although yeast is a one-celled fungus, most fungi are multicellular organisms. Fungi are _eukaryotes_, meaning they have a cell nucleus. Like plants, fungi have cell walls and do not move on their own.

Unlike plants, however, fungi cannot produce their own food because they do not have chloroplasts. Most fungi feed off the body of a living host or by absorbing nutrients from decaying material. Fungi reproduce sexually, releasing spores, but also reproduce asexually.

Besides the better-known mushrooms, toadstools, molds, truffles and yeast, fungi include ringworm and athlete's foot, slime molds, plant rust and smut. Blue cheese and Roquefort cheese require fungi for their flavor and distinctive appearances. Antibiotics like penicillin derives from fungus.

All Monera are single-celled organisms. Bacteria are prokaryotes, meaning they lack a nucleus. Most are microscopic, but so-called blue-green algae are actually bacteria.

Most Monera have a cell wall but no distinct organelles like chloroplasts and mitochondria. Monera DNA forms loops called plasmids. Monera reproduce using binary fission, meaning they divide into two new bacteria.

Detailed studies of bacteria have led many biologists to suggest dividing Kingdom Monera into two separate groups: Kingdom Bacteria for eubacteria (true bacteria) and Kingdom Archaea for archaebacteria. Another proposed change reorganizes life into three domains: Archaea, Eubacteria and Eukaryota (multicellular organisms with a nucleus).

The proposed separation of eubacteria and archaebacteria arises from distinct differences between them. Archaebacteria are generally smaller than the eubacteria with simpler internal structures. Archaebacteria cell walls and membranes differ chemically from eubacteria.

Many survive by chemosynthesis. Archaebacteria live in extreme environments like deep-sea vents and petroleum deposits, surviving in high pressure, high temperature, high salinity and anaerobic environments.

Many bacteria cause diseases like strep throat, staph infections, bacterial pneumonia and tuberculosis. Other bacteria perform essential functions, such as the digestive qualities of bacteria in the intestines.

One common characteristic of fungi and bacteria is cell walls. Many types of bacteria, both archaebacteria and eubacteria, and fungi have cell walls.

Some types of bacteria and fungi cause serious, even deadly, health problems. Other bacteria and fungi benefit humans, as with the digestive benefits of gut bacteria like E. coli and the use of yeast to make bread, beer and wine.

The nucleus is perhaps the most important difference between bacteria and fungi. Bacteria don't have a nucleus while fungi do have a nucleus.

The DNA of bacteria forms a nucleoid and small circular pieces of DNA called plasmids that float within the cytoplasm. On the other hand, the DNA of fungi (and other eukaryotes) is linear and separated from the rest of the cell by the nuclear membrane except during mitosis (cell division). Bacteria "learn" by exchanging plasmids when they join with another bacteria, allowing characteristics like antibiotic resistance to be shared.

Another difference between Monera and fungi lies in the composition of the cell walls. Fungi cell walls usually are made of chitin. Eubacteria cell walls contain peptidoglycan. Archaebacteria do not contain either substance, although the cell walls of some archaebacteria contain a substance similar to peptidoglycan.

Bacteria, whether eubacteria or archaebacteria, are one-celled organisms. Some bacteria form clumps or strings but each cell functions independently. Fungi, except for yeast, are multicellular organisms with specialized cells.