Of the five kingdoms (Monera, Protista, Plantae, Fungi and Animalia) Monera is the only "kingdom" containing prokaryotic organisms. Remember that the classification we are using is outdated and that "Kingdom Monera" is now 2 domains, the Archaebacteria and the Eubacteria.
Prokaryotic cells are characterized by having no membrane bound organelles. This means they have no nucleus or any other specialized sections of the cell. Due to this lack, these cells are limited by the rate of diffusion across the cell to obtain nutrients and other necessities. As a result, these organisms are single cells and very small.
These cells can be compared to more advanced cells, the eukaryotic cells, which have membrane bound organelles. These organelles are specialized areas within the cell that are partitioned via sections of cell membrane. The specialization allows for movement other than simple diffusion across the cell, further allowing for an increase in cell size, and ultimately to the specialization of groups of cells (tissues), giving rise to multicellular creatures.
Images courtesy of Molecular Expressions
Click here for a brief time line of the history of earth.
Bacteria are generally classified first by the shape of the cell. There are three shapes of bacteria.
|Bacilli (rod shaped)||Cocci (ball shaped)||Spirilli (corkscrew shaped)|
Gram staining is another method of classifying bacteria, based on the structure of the cell wall. Bacterial cell walls are composed of peptidoglycan molecules arranged in a grid-like structure around the cell. A gram positive cell will appear purple because the cell wall is composed only of these peptidoglycans. A gram negative cell will appear pink because in addition to the peptidoglycans, there is a lipid bilayer coating the grid, preventing the gram stain from sticking to the cell.
Antibiotics are substances that prevent the proliferation of bacteria. They tend to be effective against particular bacteria depending on cell wall structure. We observed plates of bacteria treated with various antibiotics to see if the bacteria were sensitive to the antibiotic.
Symbiosis is defined as two or more organisms living together. It is common
that one of the organisms lives in or on the other. Mutualism is where both
organisms benefit from this association. Commensalism is when one organism
benefits and the other is neither helped nor harmed. Parasitism is where one
benefits by harming the other.
We looked at Rhizobium, a nitrogen fixing bacterium. These bacteria are important in terms of ecology and agriculture by providing plants with organic nitrogen (usable nitrogen) from the atmospheric nitrogen the bacterium took in.
Cyanobacteria are photosynthetic prokaryotes. We looked at Oscillatoria and Anabaena.
Taxonomic classification is the system used by biologists to provide a unique name to every living organism. The hierarchy of classification is:
Each species belongs to a genus, each genus belongs to a family, and so on through order, class, phylum, and kingdom. Associations within the hierarchy reflect evolutionary relationships, which are deduced typically from morphological and physiological similarities between species. So, for example, species in the same genus are more closely related and more alike than species that are in different genera within the same family.
Carolus Linnaeus, an 18th-century Swedish botanist, devised the system of binomial nomenclature used for naming species. In this system, each species is given a two-part Latin name, formed by appending a specific epithet to the genus name. By convention, the genus name is capitalized, and both the genus and species names are italicized
|Modern taxonomy recognizes five kingdoms, into which the estimated five million species of the world are divided. This table presents a familiar organism from each kingdom and the names of the taxonomic groups to which it belongs.|
Kingdom Protista is a very large, diverse group of organisms. Because of the wide range of organisms, there is quite a bit of disagreement about the classification of this kingdom. So for now, the protists are grouped by their method of locomotion and energy obtainment.
Movement is achieved by several different methods in the protists.
|Cilia - Microscopic hair like projections extending from the surface of a cell or unicellular organism. Capable of rhythmical motion, they act in unison to bring about the movement of the cell or of the surrounding medium||Paramecium|
|Flagella - A long, threadlike appendage, especially a whip like extension of certain cells or unicellular organisms, found singly or in in pairs.||Euglena|
|Pseudopodia - A temporary projection of the cytoplasm of certain cells, such as phagocytes, or of certain unicellular organisms, especially amoebas.||Amoeba|
Protists are classified by how they acquire energy. Often a single method is specific to a single protist. There are four grouping of how energy is obtained.
- Photosynthetic autotroph
- Chemosynthetic autotroph
- Heterotroph by ingestion
- Heterotroph by absorption
Photosynthetic autotrophs make their own food using energy from light to power complex chemical reactions to make glucose. Chemosynthetic autotrophs do the same thing using energy obtained from the breakdown of chemicals.
Heterotrophs require food as they cannot make their own. Heterotrophs by ingestion eat by consuming food; taking it into their bodies to be digested by enzymes. Nutrients are then released from within the body. Heterotrophs by absorption eat by secreting digestive enzymes outside of their bodies, then absorbing the nutrients into their bodies.
Kingdom Fungi is made up of multicellular eukaryotes. Many of these organisms are important decomposers and survive by digesting dead organisms (saprophytes), while others are parasites. There are four divisions that make up the fungi kingdom: Chytridiomycota (fossil fungus), Ascomycota (the sac fungi), Basidiomycota (the club fungi-mushrooms), and Zygomycota. Organisms in the kingdom share a number of characteristics. Fungi can be found marine, freshwater and terrestrial habitats and are heterotrophic, which means the organism cannot create its own food and is dependent on complex organic substances for nutrition. The body of a fungus is called the mycelium and it grows underground. The mycelium is made up of many individual filamentous hyphae, threadlike strings of cells, in a tangled mass. It is thought that some fungi myceliums may be the biggest living organisms on the planet, covering a span of several states in the soil.
Many fungi form fruiting bodies which produce spores. Spores are reproductive structures and can be sexual or asexual (conidia).
Chytridiomycetes are the most primitive fungi. They are aquatic with chitinous cell walls, and their spores are flagellated.
There are ~1000 species of Zygomycetes, most of which are terrestrial decomposers. They reproduce asexually, through asexual spores contained in sporangia, and sexually, through the fusion of two different mating strains of hyphae creating a zygosporangium. Rhizopus stolonifer (bread mold) is a zygomycete.
Zygospores - conidia (asexual) Zygospores (asexual) Zygosporangia (sexual)
This division of ~25,000 species is made up of decomposers, parasites, and mutualists. They only reproduce sexually by forming elaborate fruiting bodies, called basidiocarps (commonly known as mushrooms or toadstools). Inside the basidiocarp are millions of tiny, club-shaped cells called basidia, each producing four sexual spores. Basidomycetes come in all shapes and sizes and colors.
Birds Nest Fungi
Basidia with spores
Wheat rust (Puccinia) is also a member of Division Basidiomycota.
The Ascomycetes, made up of decomposers, mutualists, and parasites, are the largest group of fungi with ~60,000 species. The diverse group includes yeasts, powdery mildew molds, penecillium molds, and cup fungi. They reproduce asexually, through conidia, and sexually. The sexual fruiting body, known as the ascocarp, contains many characteristic sacs, known as asci, which contain up to eight sexual spores.
One of the characteristics of the sac fungi, Tuber melanosporum, is they emit a strong odor and cooks would use pigs (because of their keen smell) to search the undergrowth and locate this fungi for use in the delicacy called "Truffles". If you have ever seen the movie "Ever After", the peasant girl (Drew Barrymore) had her pig out looking for "Truffles" when she ran into the prince along the road. The morel mushroom, highly sought after in Iowa, is also a member of this phylum.
Cup Fungi Powdery mildew Morchella (morel) Yeast Penicillium Cup Fungi asci Mildew Asci Morel ascospores Yeast ascus Conidiaphores
Lichens are mutualistic associations between a fungus and an algae (usually Ascomycetes), where the fungus provides a safe environment and minerals to the algae and the algae provides sugars to the fungus. Together, they are often considered as separate organisms or even called species, but realize lichens represent two species living together in a mutualistic relationship.
Often lichens are the first to "colonize" exposed rocks initiating the generation of soil from rock. They "reproduce" by producing soredia (a specialized asexual reproductive unit) composed of fungal hyphae surrounding algae. These small structure may be air or water borne to new locations thus spreading the lichens. It is a distribution mechanism and not a reproduction mechanism. The fungal members of a lichen symbiosis may reproduce sexually by producing ascocarps or basidiocarps.
Lichens can survive in extreme environments such as Antarctica or a desert living on rocks, trees, and in soil. They are good monitors of environmental pollution because of their ability to absorb nutrients from substrate, air, and rain. Their rate of growth is at a rate of 0.1-10mm/yr (VERY SLOW).
- Organisms can be classified as either prokaryotic or
eukaryotic. List 4 distinguishing structural features of each group.
- Define symbiosis and give an example.
- There are three types of symbiotic relationships. What are they and how is each defined?
- Fungi use both sexual and asexual forms of reproduction. During times of unfavorable environmental conditions they reproduce sexually. Why do you think this would be beneficial to the fungus?
- Penicillin belongs to what Kingdom?
- ____________ cells are unique to the Kingdom Monera.
- ____________ is one organism (bacteria) that was observed in lab in the Kingdom Monera.
- 0.04 kilometers are how many centimeters?
- Is a paramecium an autotroph or heterotroph?
- The body of a fungi is composed of thread like multicellular filaments called:
- List the three basic shapes of bacterial cells.
- Which are physically larger: monerans or protists?
- Which statement(s) is(are) true?
1. monerans are protists are prokaryotic
2. monerans and fungi reproduce sexually
3. prokaryotic cells are smaller and less complex than eukaryotic cells
4. prokaryotic cells existed before eukaryotic cells
5. most fungi are parasitic
6. prokaryotic cells are very large with an easily distinguishable nucleus
7. asexual reproduction is usually used by fungi during unfavorable conditions
8. there are three different shapes of Eubacteria
9. in the kingdom Fungi, most species are saprophytes
- List the major categories of the classification system in order.
- Define Phylogeny.
- Draw a phylogeny of the 6 kingdom classification system.
- What is the structural difference between a gram positive cell wall and a gram negative cell wall?
- How can protists be differentiated from animals?
- How can fungi be differentiated from plants?
- Cyanobacteria (blue-green algae) belong in which kingdom?
- Gram positive bacteria become ________________ (color) after gram staining, indicating the absence of a ___________.
- Blue-green algae belongs to which kingdom?
- Green algae belongs to which kingdom?
- Explain the difference between heterotrophic and autotrophic protists and provide and example of each.
- Which is the more primitive type of cell? (prokaryote, eukaryote) Name two things the more primitive type of cell lacks.